Got a friend with a few problems with his car. He just added a sard fuel rail and fpr.
Evo8 running 96940011
His current fuel system:
walbro 255
sard fuel rail
sard fpr - running factory vac line from mani, but not through the solenoid.
rc 1000cc injectors

when I first got to his house, he had neglected to tell me that he had set his fpr to 90psi...which he had done thinking he wasn't getting fuel. I quickly noticed that his pressure was waaaaaaaaay to high, and his fuel pump wasn't even turning when he cranked the car. Within seconds I told him to stop, and reset his fpr for 38psi. The car started just fine afterwards and idled just fine.

But here is the problem, when we start to go past 3000rpm his car stutters and his afr's shoot up to the 20's.
Rom is scaled perfectly (before fpr) for the injectors, and datalogging shows no change in ipw's or load from before and after. Afr swings at idle from 14.7-16.8, tried changing then rail pressure up and down without major changes. At 25psi the car idled much better (afr wise), but still couldn't go past 3k.

Could he have burnt out his fuel pump? or severely messed up his fuel system from running such a high rail pressure (basically choking the fuel pump)?

Any help is appreciated

 

I'm having the same problem, just that mine started running lean after my inline fuel pump..

 

To the O.P: For what reason were the original factory FPR and rail changed out? Why go to an adjustable FPR and non-factory rail anyway? There are several nine second Evos on the factory FPR!

 

You will be guessing unless you get a means of monitoring FP while driving the car. One good item to have costs only $25 shipped:
Fuel Pressure Tester

IF the pressure on the rail gauge you have drops to zero immediately upon shutting off the engine while at idle, it could indicate a problem with the regulator.

Another issue is that the in-tank pump has an internal pressure relief valve that begins to open around 75 psi. IF he cranked the FPR to get 90 psi from the pump at idle, who knows what that did? For all we know, the relief valve is jammed open.

I'm just taking educated guesses, but cranking the pressure to 90 psi was a no-no. Nevertheless, I'd suspect the pump before the FPR.

 

^ thanks. Were going to throw the car on the dyno and watch the gauge. That will tell us right away what the problem is.

To the guy that asked: he got a fpr cause I don't know why. Only thing I figure is some shop convinced him he must have it, so he bought it.

 

Bump for any insight

 

K. So we got it up on the dyno, the fuel pressure remains a constant 38-40psi all through the rpm band. Still stuttering and running super lean.
Again the computer spits out data saying everything is in check...I'm stumped. Any help?

 

38-40 psi all the way through, huh? How much boost?

 

Can you reinstall the stock regulator to see if that cures the problem? I once bought a nice looking, billet aluminum, adjustable regulator from KenneBell and it was defective right out of the box. When I installed it the car would just lay down on its face and burble. It just wouldn't run at all. They replaced the defective regulator with another defective one. So, you may want to swap the stock regulator back on just for comparison's sake.

 

fuel pressure should rise as boost is applied.. sounds like fuel pump is dead.

 

Ok, so eventhough he swore he installed the fpr properly...I decided to switch the feed and return line. It works! Guy had it installed backwards. Now the pressure rises an falls with vac. I'll tune it up and post any findings.

 

nice. good find.