ridenrunwv

What psi is preferred for activating a second fuel pump? I've been playing with having mine power on at different RPMs to try to limit a rich spot I'm getting after it comes on. I've looked at a bunch of E85 double pumper dyno graphs and some briefly dip into the 10s like I'm seeing so I'm guessing that's when the second pump is coming on.

I've seen some double pumper graphs that never drop below 11 AFR and you can't even tell when the 2nd pump comes on.

I hooked my pump up before setting the engagement and don't want to unhook it so I'm just going by logs to get an idea of when mine is coming on.

How much of a delay would there be between when the 2nd pump powers on and when I see my AFR get rich in my logs? I'm guessing it's not instant and that the pump comes on and there is some delay before you start to see the rich AFRs.

Right now I have it set where my log gets rich around 18 psi during WOT pulls but feel like bumping it up even more might help.

bsh

iTrader: (1)

I use injector duty cycle as switch-on condition for my 2nd fuel pump.
I dont feel rpm only is a good way to determine fuel demand, as you can have 0 psi boost@5000 rpm and you can have 30 psi boost@5000 rpm. They require a different amount of fuel supply...

evo8426

iTrader: (27)

I have mine set to around 15psi. I don't have any weird fuel dips. The only time the 2nd pump is needed is over 5500rpm when a single can't keep up the supply.

ridenrunwv

I'm not sure why I put RPM in that title. I meant pressure. Can't even set it up to a certain RPM. I'm going to try to set mine even higher. I've seen multiple people say 15 psi now from research I've done. Even though I'm seeing a dip in AFR at around 18 psi I have a feeling my pump is coming on well before that and it takes that long to flow the fuel to the rail. I saw my AFR dip at a certain PSI before and let boost build really slow watching my boost gauge and discovered that my pump came on before that but it just took a little time on a WOT pull to see the effects of the second pump.