Buschur Racing fuel system solutions....
Oct 14, 2006, 04:53 AM
#16
The single pump does not have enough volume to feed 4-1200 cc injectors. You end up sucking the line dry (basically) and you end up with the fuel pressure dropping. So while you might see 80 psi peak as the RPM's climb it falls to 50 psi.
The twin pumps do not overrun the stock regulator as the second pump isn't on until it is needed. If you ran them both at idle then the stock regulator could be a problem, I see no sense in running the second pump 100% of the time, car doesn't need it. Mine comes on at 6,000 rpm or 30 psi of boost, whichever happens first. I did this so the second pump doesn't come on while trying to launch the car on the two step, as it isn't need then either.
The twin pumps do not overrun the stock regulator as the second pump isn't on until it is needed. If you ran them both at idle then the stock regulator could be a problem, I see no sense in running the second pump 100% of the time, car doesn't need it. Mine comes on at 6,000 rpm or 30 psi of boost, whichever happens first. I did this so the second pump doesn't come on while trying to launch the car on the two step, as it isn't need then either.
Oct 14, 2006, 06:18 AM
#17
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Originally Posted by l2r99gst
Dave,
How can your duty cycle go down if you're using the same injectors, unless your dramatically increasing the fuel pressure via the second pump?
And, if you're increasing the fuel pressure that much, I doubt the stock FPR wouldn't be overrun, yet you say that it works fine. Isn't the stock FPR slightly overrun at idle even with one normal 255?
Am I missing something here?
Eric
How can your duty cycle go down if you're using the same injectors, unless your dramatically increasing the fuel pressure via the second pump?
And, if you're increasing the fuel pressure that much, I doubt the stock FPR wouldn't be overrun, yet you say that it works fine. Isn't the stock FPR slightly overrun at idle even with one normal 255?
Am I missing something here?
Eric
David, It was my understanding that the modded pumps you seel are really meant ot improve the flow at higher pressures. By running the second pump aren't you effectively "spltting" the pressure seen by each pump, making the modded pump obsolete?
I think somehting like this would do well in the dsm cam as well as that is one of my next projects.
EDIT: I guess I could have saved the time typing if I would have looked at the next page
Oct 14, 2006, 07:12 AM
#18
I understand, I just wanted to make sure that was the case, since Dave just talked about duty cylces with the 1200CC injectors and that wouldn't change unless the fuel pressure was changing.
Since the fuel pressure was dramatically dropping off with the single pump, the injectors had to be run at a much higher IPW to feed enough fuel and since the second pump now beings the presssure back up to where it should be, the IPW could be dialed back to a more normal value, lowering the duty cycle.
It's not that I didn't understand, I just wanted to make sure this was explained and the reasons why a second pump was needed and how it worked.
Eric
Since the fuel pressure was dramatically dropping off with the single pump, the injectors had to be run at a much higher IPW to feed enough fuel and since the second pump now beings the presssure back up to where it should be, the IPW could be dialed back to a more normal value, lowering the duty cycle.
It's not that I didn't understand, I just wanted to make sure this was explained and the reasons why a second pump was needed and how it worked.
Eric
Oct 16, 2006, 05:42 AM
#20
evo08, nobody in PR has this same twin pump, this is the only one that has been built.
Update from the weekend.
With the additional power the car is making, getting it to hook up on Yokahama Neova's was nearly impossilbe. Trent was either pedaling the car in 1st or letting it bang the revlimiter 6-7 times through first. Best 60' time was 1.76. Car ran 10.15, 10.2, 10.2 and 10.4.
Fuel system worked perfectly.
More on the fuel system.
The factory fuel pump gets only 9.5 volts at idle and low RPM. It has a series of relays that bump that voltage when the RPM increases.
The HO Walbro pump we have flows substantially more as the pressure goes up compared to any other intank Walbro pump sold.
This double pumper has TWO of these HO Walbro pumps in the tank. At idle and low rpm the main pump is run at 9.5 volts just like stock and then when the rpm's increase the voltage is bumped up to 13+ just like stock. I am turning the second pump on at 20 psi (I think before I said I had it coming on at 30 psi and 6,000 rpm). When the second pump comes on both these pumps are getting 13+ volts and both are running.
Update from the weekend.
With the additional power the car is making, getting it to hook up on Yokahama Neova's was nearly impossilbe. Trent was either pedaling the car in 1st or letting it bang the revlimiter 6-7 times through first. Best 60' time was 1.76. Car ran 10.15, 10.2, 10.2 and 10.4.
Fuel system worked perfectly.
More on the fuel system.
The factory fuel pump gets only 9.5 volts at idle and low RPM. It has a series of relays that bump that voltage when the RPM increases.
The HO Walbro pump we have flows substantially more as the pressure goes up compared to any other intank Walbro pump sold.
This double pumper has TWO of these HO Walbro pumps in the tank. At idle and low rpm the main pump is run at 9.5 volts just like stock and then when the rpm's increase the voltage is bumped up to 13+ just like stock. I am turning the second pump on at 20 psi (I think before I said I had it coming on at 30 psi and 6,000 rpm). When the second pump comes on both these pumps are getting 13+ volts and both are running.
Oct 16, 2006, 09:35 AM
#23
Dave has forgotten more about 4g63s than I ever knew, and I appreciate his candor in giving us the benefit of his testing and experience, and also his honesty in telling us when something was limiting his car's potential.
So, Dave, please take this as a customer wanting to understand more. It seems to me that if you use some signal to turn on the second pump, rather than have it on all the time, all of the "solutions" mentioned so far, including yours, seem to have the same problem -- they do not accurately control the fuel pressure. In order to have a fact base on what is happening to the fuel pressure, one would have to measure the fuel pressure changes (if any) while on a dyno under load. I bet you've already done that, which is how you knew that the fuel pressure was falling off. You said that even with your modified HO Walbro 255 pump, the fuel pressures were dropping and so your HP was limited by lack of fuel. Did you saw the wideband A/F ratios going up, and add more fuel in your standalone fuel map cells at that RPM/load range to make up for the fact that the pressure was dropping? Without that, I'd think that you'd run lean due to lack of fuel, or have to limit the air flow by boost control. Now that you have proper pressure, and picked up 50HP, did you pull that "extra" fuel back out of the those cells to get your A/F ratios where you wanted them with the correct fuel pressure?
I remember that you told us that Curt Brown's car with the 35R was getting much more out of the 35R tune that other cars that you did. Curt said was running a full custom twin pump fuel setup. Would you say that that now explains a part of the puzzle of why Curt's car was getting better HP numbers than other 35R's you were tuning?
I understand that the optimum fuel system is one that gives you all the fuel your engine needs at the pressure your ECU is using to calculate the fuel maps controlling your injectors. Any change from that fuel pressure (up or down) screws with your air fuel ratio, and makes you run richer or leaner, as the case may be.
Triggering a second pump will affect the fuel pressure in the system. How do you determine when to trigger the second pump (if you don't have them both running all the time)? When the second pump goes on, higher than stock line pressure will result in higher than stock volume injected by the injectors when they open. In the time before the second pump comes on, if the pressure is dropping, as you said was happening on your car, you will not have enough fuel for the motor, and would run the risk of going lean, right? I think you corrected that by looking at the A/F readings from a wideband and modifying the fuel maps in the AEM, but how would someone with a stock ECU solve for the variations in fuel pressure and resulting changes in fuel supplied?
Would you need a fuel pressure gauge to know what's happening as you run the motor, and be able to compare the readings to a boost measurement to know if your pressure is rising 1:1 as it should to maintain accurate control by the ECU of the fuel volumes injected? Even if you knew what was going on with your fuel system pressures, how would you control air/fuel ratios with a stock type ECU if the pressure is fluctuating at anything besides the 1:1 that the ECU is programmed to assume?
I understood that these complexities were the reason that many twin pump fuel systems are designed to supply the necessary volume of fuel at the pressure you want for the highest anticipated fuel consumption, and at anything less than full need for fuel, return the "extra" to the system through the adjustable fuel pressure regulator and a larger return line. Of course, that kind of fuel system has more parts and thus costs more than the addition of a second pump.
Any comments from your experience would be much appreciated. Thanks, Dave!
So, Dave, please take this as a customer wanting to understand more. It seems to me that if you use some signal to turn on the second pump, rather than have it on all the time, all of the "solutions" mentioned so far, including yours, seem to have the same problem -- they do not accurately control the fuel pressure. In order to have a fact base on what is happening to the fuel pressure, one would have to measure the fuel pressure changes (if any) while on a dyno under load. I bet you've already done that, which is how you knew that the fuel pressure was falling off. You said that even with your modified HO Walbro 255 pump, the fuel pressures were dropping and so your HP was limited by lack of fuel. Did you saw the wideband A/F ratios going up, and add more fuel in your standalone fuel map cells at that RPM/load range to make up for the fact that the pressure was dropping? Without that, I'd think that you'd run lean due to lack of fuel, or have to limit the air flow by boost control. Now that you have proper pressure, and picked up 50HP, did you pull that "extra" fuel back out of the those cells to get your A/F ratios where you wanted them with the correct fuel pressure?
I remember that you told us that Curt Brown's car with the 35R was getting much more out of the 35R tune that other cars that you did. Curt said was running a full custom twin pump fuel setup. Would you say that that now explains a part of the puzzle of why Curt's car was getting better HP numbers than other 35R's you were tuning?
I understand that the optimum fuel system is one that gives you all the fuel your engine needs at the pressure your ECU is using to calculate the fuel maps controlling your injectors. Any change from that fuel pressure (up or down) screws with your air fuel ratio, and makes you run richer or leaner, as the case may be.
Triggering a second pump will affect the fuel pressure in the system. How do you determine when to trigger the second pump (if you don't have them both running all the time)? When the second pump goes on, higher than stock line pressure will result in higher than stock volume injected by the injectors when they open. In the time before the second pump comes on, if the pressure is dropping, as you said was happening on your car, you will not have enough fuel for the motor, and would run the risk of going lean, right? I think you corrected that by looking at the A/F readings from a wideband and modifying the fuel maps in the AEM, but how would someone with a stock ECU solve for the variations in fuel pressure and resulting changes in fuel supplied?
Would you need a fuel pressure gauge to know what's happening as you run the motor, and be able to compare the readings to a boost measurement to know if your pressure is rising 1:1 as it should to maintain accurate control by the ECU of the fuel volumes injected? Even if you knew what was going on with your fuel system pressures, how would you control air/fuel ratios with a stock type ECU if the pressure is fluctuating at anything besides the 1:1 that the ECU is programmed to assume?
I understood that these complexities were the reason that many twin pump fuel systems are designed to supply the necessary volume of fuel at the pressure you want for the highest anticipated fuel consumption, and at anything less than full need for fuel, return the "extra" to the system through the adjustable fuel pressure regulator and a larger return line. Of course, that kind of fuel system has more parts and thus costs more than the addition of a second pump.
Any comments from your experience would be much appreciated. Thanks, Dave!
Oct 16, 2006, 10:37 AM
#24
Below is post #23 cut and pasted so I can answer it in detail, my replies have ** infront of them:
Dave has forgotten more about 4g63s than I ever knew, and I appreciate his candor in giving us the benefit of his testing and experience, and also his honesty in telling us when something was limiting his car's potential.
**Thank you.
So, Dave, please take this as a customer wanting to understand more. It seems to me that if you use some signal to turn on the second pump, rather than have it on all the time, all of the "solutions" mentioned so far, including yours, seem to have the same problem -- they do not accurately control the fuel pressure. In order to have a fact base on what is happening to the fuel pressure, one would have to measure the fuel pressure changes (if any) while on a dyno under load. I bet you've already done that, which is how you knew that the fuel pressure was falling off. You said that even with your modified HO Walbro 255 pump, the fuel pressures were dropping and so your HP was limited by lack of fuel.
**Correct. You have to monitor fuel pressure. What you have to remember is this, the single fuel pump does have enough fuel to run the injectors correctly up to a given HP level. In my case the fuel pump was just fine to about 500 whp. After that in order to get enough fuel to the engine, because the fuel pressure was dropping off, I had to keep increasing the size and duty cycle of the injectors. The HP was limited by "lack of fuel" which kept me from running my boost or RPM. So in actuality I was making as much power as I could make at 35 psi and 8500 rpm. In order for me to make more power (adding boost or RPM) I needed more fuel. That is why I gained an additional 50 whp, the boost was able to get turned up and I could run up to any RPM point I chose. We did monitor the fuel pressure, it was hitting 85 psi and then falling rapidly to less than 60 psi.
Did you saw the wideband A/F ratios going up, and add more fuel in your standalone fuel map cells at that RPM/load range to make up for the fact that the pressure was dropping? Without that, I'd think that you'd run lean due to lack of fuel, or have to limit the air flow by boost control. Now that you have proper pressure, and picked up 50HP, did you pull that "extra" fuel back out of the those cells to get your A/F ratios where you wanted them with the correct fuel pressure?
**Yes, this is exactly what I had to do. By the time I was done and realized there was a problem I was over 100% duty cycle. That's when we took a look at the fuel pressure and knew the pump wasn't enough. After the double pumper was installed I dyno'd the car again just using the single pump. I wanted to make sure the single pump flowed properly and that in fact it was running out. After a 3rd and 4th gear pull to confirm this I triggered the second pump to come on. When I did this the car would not pull, it was misfiring and running horribly, the AFR's went from 12:1 to off the scale rich past 9:1. I then started pulling fuel out of the map and when I got the AFR's down to around 11.5:1 where I wanted them the duty cycles had fallen from +100% down to 65%.
I remember that you told us that Curt Brown's car with the 35R was getting much more out of the 35R tune that other cars that you did. Curt said was running a full custom twin pump fuel setup. Would you say that that now explains a part of the puzzle of why Curt's car was getting better HP numbers than other 35R's you were tuning?
**Curt's car had a fuel system in it using two pumps. He also ran out of fuel on the dyno and his fuel pressure was dropping. I didn't tell the entire story at the time. We took the car off the dyno and installed our single HO pump in place of his standard Walbro after I had dyno'd it. Curt then took the car down the road and his AFR's were also pegged at 9:1. We then tuned it by making street pulls. This is when he ran 9.3 at 151 mph. I have no explanation for why Curt's car is stronger than any other GT35R car. It was NOT the fuel system though.
I understand that the optimum fuel system is one that gives you all the fuel your engine needs at the pressure your ECU is using to calculate the fuel maps controlling your injectors. Any change from that fuel pressure (up or down) screws with your air fuel ratio, and makes you run richer or leaner, as the case may be.
**The ECU doesn't directly monitor and calculate fuel maps factory in fuel pressure. Yes, FP will effect the mapping, mostly because that is a parameter that is not monitored or taken into consideration directly. The ECU knows what injector and pressure it had when the facotry calibrated it, it also knows that in stock form for every gram of air it takes in it has to add X amount of fuel to hit the target AFR. If you change FP then it is going to mess with the factory ECU's calculation.
Triggering a second pump will affect the fuel pressure in the system. How do you determine when to trigger the second pump (if you don't have them both running all the time)? When the second pump goes on, higher than stock line pressure will result in higher than stock volume injected by the injectors when they open. In the time before the second pump comes on, if the pressure is dropping, as you said was happening on your car, you will not have enough fuel for the motor, and would run the risk of going lean, right?
**This goes back to what I started to say in the first paragraph. Yes, at some point the FP will start to drop. What I did when I tuned my car was found where I was reaching about 80% duty cycle and triggered the second pump there. That was around 20 psi of boost. I messed with triggering it from boost and rpm, boost alone and RPM alone. In the end I stuck with boost alone and it has worked perfectly. I just looked up some logs to give some examples of this stuff. When the car went 9.97 at 142 mph, looking at 4th gear, the car hit 100.4% duty cycle at 35 psi and 7879 rpm. By the time it crossed the finish line the duty cycle was 112.8%, 33 psi and 9281 rpm. NOW with the double pumper the car, this weekend went 10.15 (spinning pretty bad) at 142 mph. Now at the end of 4th gear the car has 35 psi and the same 9200 rpm but the injector duty cycle is 64.32%. This is a drastic change. Looking at the log from the entire pass it is pretty cool. The car is on the two step before it launches, as soon as the clutch is released it hits 20 psi and the second pump comes on. From there until the end of the run the duty cycle stays right at 64%. This makes sense as they dyno graph of the car shows about 570 whp at 6500 and has 590 at 8500 rpm. So it is a flat line. While the duty cycle should increase as the RPM's do in this car the turbo is loosing a little boost as it climbs too so the duty cycle is offset.
I think you corrected that by looking at the A/F readings from a wideband and modifying the fuel maps in the AEM, but how would someone with a stock ECU solve for the variations in fuel pressure and resulting changes in fuel supplied?
**You would do the same thing, you'd have to remap the factory ECU.
Would you need a fuel pressure gauge to know what's happening as you run the motor, and be able to compare the readings to a boost measurement to know if your pressure is rising 1:1 as it should to maintain accurate control by the ECU of the fuel volumes injected? Even if you knew what was going on with your fuel system pressures, how would you control air/fuel ratios with a stock type ECU if the pressure is fluctuating at anything besides the 1:1 that the ECU is programmed to assume?
**You have to remember, any changes in the factory installed components changes the way the factory ECU calculates the AF tables. The exhaust changes it, boost pressure and of course the big one MAF data. The nice thing about the way I am running the fuel system is it takes away what you are thinking. You are assuming the FP is going up because of the two pumps. It doesn't. The reason it doesn't is at idle, cruise and low boost the car runs one single pump just like always. If you figure out when your single pump starts to loose pressure you turn the second pump on just before that point. You then maintain the fuel pressure you had. If you did find that the two pumps were over running the stock regulator you could just install a larger aftermarket regulator to fix that. The stock regulator will is small inside and will only bypass so much fuel back to the tank. I do not seem to be having this problem and if you don't install the pump until your single runs out you won't have a problem either. I am not fixing the fuel problem with this double pumper by upping the pressure, it is being fixed by upping the volume of fuel.
I understood that these complexities were the reason that many twin pump fuel systems are designed to supply the necessary volume of fuel at the pressure you want for the highest anticipated fuel consumption, and at anything less than full need for fuel, return the "extra" to the system through the adjustable fuel pressure regulator and a larger return line. Of course, that kind of fuel system has more parts and thus costs more than the addition of a second pump.
**I have experience with only one other system similar to this one I built. It also uses stock lines and such. It is triggered from a pressure switch and thousands are being used, it is a very good system.
Dave has forgotten more about 4g63s than I ever knew, and I appreciate his candor in giving us the benefit of his testing and experience, and also his honesty in telling us when something was limiting his car's potential.
**Thank you.
So, Dave, please take this as a customer wanting to understand more. It seems to me that if you use some signal to turn on the second pump, rather than have it on all the time, all of the "solutions" mentioned so far, including yours, seem to have the same problem -- they do not accurately control the fuel pressure. In order to have a fact base on what is happening to the fuel pressure, one would have to measure the fuel pressure changes (if any) while on a dyno under load. I bet you've already done that, which is how you knew that the fuel pressure was falling off. You said that even with your modified HO Walbro 255 pump, the fuel pressures were dropping and so your HP was limited by lack of fuel.
**Correct. You have to monitor fuel pressure. What you have to remember is this, the single fuel pump does have enough fuel to run the injectors correctly up to a given HP level. In my case the fuel pump was just fine to about 500 whp. After that in order to get enough fuel to the engine, because the fuel pressure was dropping off, I had to keep increasing the size and duty cycle of the injectors. The HP was limited by "lack of fuel" which kept me from running my boost or RPM. So in actuality I was making as much power as I could make at 35 psi and 8500 rpm. In order for me to make more power (adding boost or RPM) I needed more fuel. That is why I gained an additional 50 whp, the boost was able to get turned up and I could run up to any RPM point I chose. We did monitor the fuel pressure, it was hitting 85 psi and then falling rapidly to less than 60 psi.
Did you saw the wideband A/F ratios going up, and add more fuel in your standalone fuel map cells at that RPM/load range to make up for the fact that the pressure was dropping? Without that, I'd think that you'd run lean due to lack of fuel, or have to limit the air flow by boost control. Now that you have proper pressure, and picked up 50HP, did you pull that "extra" fuel back out of the those cells to get your A/F ratios where you wanted them with the correct fuel pressure?
**Yes, this is exactly what I had to do. By the time I was done and realized there was a problem I was over 100% duty cycle. That's when we took a look at the fuel pressure and knew the pump wasn't enough. After the double pumper was installed I dyno'd the car again just using the single pump. I wanted to make sure the single pump flowed properly and that in fact it was running out. After a 3rd and 4th gear pull to confirm this I triggered the second pump to come on. When I did this the car would not pull, it was misfiring and running horribly, the AFR's went from 12:1 to off the scale rich past 9:1. I then started pulling fuel out of the map and when I got the AFR's down to around 11.5:1 where I wanted them the duty cycles had fallen from +100% down to 65%.
I remember that you told us that Curt Brown's car with the 35R was getting much more out of the 35R tune that other cars that you did. Curt said was running a full custom twin pump fuel setup. Would you say that that now explains a part of the puzzle of why Curt's car was getting better HP numbers than other 35R's you were tuning?
**Curt's car had a fuel system in it using two pumps. He also ran out of fuel on the dyno and his fuel pressure was dropping. I didn't tell the entire story at the time. We took the car off the dyno and installed our single HO pump in place of his standard Walbro after I had dyno'd it. Curt then took the car down the road and his AFR's were also pegged at 9:1. We then tuned it by making street pulls. This is when he ran 9.3 at 151 mph. I have no explanation for why Curt's car is stronger than any other GT35R car. It was NOT the fuel system though.
I understand that the optimum fuel system is one that gives you all the fuel your engine needs at the pressure your ECU is using to calculate the fuel maps controlling your injectors. Any change from that fuel pressure (up or down) screws with your air fuel ratio, and makes you run richer or leaner, as the case may be.
**The ECU doesn't directly monitor and calculate fuel maps factory in fuel pressure. Yes, FP will effect the mapping, mostly because that is a parameter that is not monitored or taken into consideration directly. The ECU knows what injector and pressure it had when the facotry calibrated it, it also knows that in stock form for every gram of air it takes in it has to add X amount of fuel to hit the target AFR. If you change FP then it is going to mess with the factory ECU's calculation.
Triggering a second pump will affect the fuel pressure in the system. How do you determine when to trigger the second pump (if you don't have them both running all the time)? When the second pump goes on, higher than stock line pressure will result in higher than stock volume injected by the injectors when they open. In the time before the second pump comes on, if the pressure is dropping, as you said was happening on your car, you will not have enough fuel for the motor, and would run the risk of going lean, right?
**This goes back to what I started to say in the first paragraph. Yes, at some point the FP will start to drop. What I did when I tuned my car was found where I was reaching about 80% duty cycle and triggered the second pump there. That was around 20 psi of boost. I messed with triggering it from boost and rpm, boost alone and RPM alone. In the end I stuck with boost alone and it has worked perfectly. I just looked up some logs to give some examples of this stuff. When the car went 9.97 at 142 mph, looking at 4th gear, the car hit 100.4% duty cycle at 35 psi and 7879 rpm. By the time it crossed the finish line the duty cycle was 112.8%, 33 psi and 9281 rpm. NOW with the double pumper the car, this weekend went 10.15 (spinning pretty bad) at 142 mph. Now at the end of 4th gear the car has 35 psi and the same 9200 rpm but the injector duty cycle is 64.32%. This is a drastic change. Looking at the log from the entire pass it is pretty cool. The car is on the two step before it launches, as soon as the clutch is released it hits 20 psi and the second pump comes on. From there until the end of the run the duty cycle stays right at 64%. This makes sense as they dyno graph of the car shows about 570 whp at 6500 and has 590 at 8500 rpm. So it is a flat line. While the duty cycle should increase as the RPM's do in this car the turbo is loosing a little boost as it climbs too so the duty cycle is offset.
I think you corrected that by looking at the A/F readings from a wideband and modifying the fuel maps in the AEM, but how would someone with a stock ECU solve for the variations in fuel pressure and resulting changes in fuel supplied?
**You would do the same thing, you'd have to remap the factory ECU.
Would you need a fuel pressure gauge to know what's happening as you run the motor, and be able to compare the readings to a boost measurement to know if your pressure is rising 1:1 as it should to maintain accurate control by the ECU of the fuel volumes injected? Even if you knew what was going on with your fuel system pressures, how would you control air/fuel ratios with a stock type ECU if the pressure is fluctuating at anything besides the 1:1 that the ECU is programmed to assume?
**You have to remember, any changes in the factory installed components changes the way the factory ECU calculates the AF tables. The exhaust changes it, boost pressure and of course the big one MAF data. The nice thing about the way I am running the fuel system is it takes away what you are thinking. You are assuming the FP is going up because of the two pumps. It doesn't. The reason it doesn't is at idle, cruise and low boost the car runs one single pump just like always. If you figure out when your single pump starts to loose pressure you turn the second pump on just before that point. You then maintain the fuel pressure you had. If you did find that the two pumps were over running the stock regulator you could just install a larger aftermarket regulator to fix that. The stock regulator will is small inside and will only bypass so much fuel back to the tank. I do not seem to be having this problem and if you don't install the pump until your single runs out you won't have a problem either. I am not fixing the fuel problem with this double pumper by upping the pressure, it is being fixed by upping the volume of fuel.
I understood that these complexities were the reason that many twin pump fuel systems are designed to supply the necessary volume of fuel at the pressure you want for the highest anticipated fuel consumption, and at anything less than full need for fuel, return the "extra" to the system through the adjustable fuel pressure regulator and a larger return line. Of course, that kind of fuel system has more parts and thus costs more than the addition of a second pump.
**I have experience with only one other system similar to this one I built. It also uses stock lines and such. It is triggered from a pressure switch and thousands are being used, it is a very good system.
Oct 16, 2006, 10:46 AM
#25
Sorry, missed two other questions.
The pump can be sold at anytime. I will have to build it and it is going to take a few days. I will also need your core first as I have no spares, they are on back order from Japan.
Chances of the second pump not coming on. Well I'd say the chances of that happening are the same as any other fuel pump failing or not coming on, maybe slightly less since it is in a sealed tank and not exposed to the elements like an external pump in a fuel cell or something else is. The more time you spend doing a good wiring job for the second pump the better off you will be too.
The pump can be sold at anytime. I will have to build it and it is going to take a few days. I will also need your core first as I have no spares, they are on back order from Japan.
Chances of the second pump not coming on. Well I'd say the chances of that happening are the same as any other fuel pump failing or not coming on, maybe slightly less since it is in a sealed tank and not exposed to the elements like an external pump in a fuel cell or something else is. The more time you spend doing a good wiring job for the second pump the better off you will be too.
Oct 16, 2006, 08:00 PM
#26
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So if you put this on your car and get it tuned and then went down the road and kicked it and the second pump didn't come on, then that would be the end of that motor. Is there any was you can make a safty on it like they have on some of the alk and meth injection kits? Why if you are not changing anything but the pump in to pumps is the price around 750? Doesn't that seem a little high? thanks
Oct 17, 2006, 06:34 AM
#27
ptevo3,
If the second pump didn't come on the engine would blow up if there were no safety margins for it. Yes, you could set up a secondary fuel/timing map (in an ECU that has that option) to save your butt.
If your stock fuel pump fails it will run out of fuel too. I don't quite understand the fear behind the second pump coming on. If you guys want it wired in directly so they both run at the same time that is easy enough to do too and is similar to how AMS's works.
Obviously you haven't looked at this fuel tank assembly, putting two pumps in it isn't easy. Consider this, one of our HO pumps is $250, two of them are $500. Then there is an external fuel filter, fittings, wiring, relay etc. plus quite a bit of labor to put it all together.
I am sure some _______ will copy this idea now that I have once again done the work to get it figured out and built it. That is how the world works. If you wait around you can probably buy something similar from Ebay for $29.99 plus $69 shipping. Give it time.
In the meantime, if you want to keep from drilling into your EVO and changing half the car over you can buy and run this
If the second pump didn't come on the engine would blow up if there were no safety margins for it. Yes, you could set up a secondary fuel/timing map (in an ECU that has that option) to save your butt.
If your stock fuel pump fails it will run out of fuel too. I don't quite understand the fear behind the second pump coming on. If you guys want it wired in directly so they both run at the same time that is easy enough to do too and is similar to how AMS's works.
Obviously you haven't looked at this fuel tank assembly, putting two pumps in it isn't easy. Consider this, one of our HO pumps is $250, two of them are $500. Then there is an external fuel filter, fittings, wiring, relay etc. plus quite a bit of labor to put it all together.
I am sure some _______ will copy this idea now that I have once again done the work to get it figured out and built it. That is how the world works. If you wait around you can probably buy something similar from Ebay for $29.99 plus $69 shipping. Give it time.
In the meantime, if you want to keep from drilling into your EVO and changing half the car over you can buy and run this
Oct 17, 2006, 09:38 AM
#30
I can build the pump assembly in a few days. Just takes some time.
I am still working on changing some things on it. What I have works but I am going to make it harder to copy piece for piece. I sent out one of the fittings to the machine shop this morning to have made custom so it won't be available to anyone else.
Having this copied is going to **** me off.
Anyway, I have everything here I need to build a few. If you want one call us, we'll give you an RA# to send in your assembly and I will get it back out within 2-3 days to you.
I am still working on changing some things on it. What I have works but I am going to make it harder to copy piece for piece. I sent out one of the fittings to the machine shop this morning to have made custom so it won't be available to anyone else.
Having this copied is going to **** me off.
Anyway, I have everything here I need to build a few. If you want one call us, we'll give you an RA# to send in your assembly and I will get it back out within 2-3 days to you.