Just went for a quick ride, here's the problem. When car was cold I turned key on - didn't start it, pressure went to 48psi, then to 44psi when pump turned off. Pressure then started to fall off to about 38psi. Started it and went for a ride. I jumped on it hard 4 times in a row. First two times I got 12# boost @ 5600rpm at 90psiin 2nd and third - was all over the road. Third time I jumped on it 2nd was like above, but in third it fell on its face at 6# at 80psi, but the pressure gauge was fluttering, couldn't get it back. Got home and shut it down and pressure gauge drops to 36psi, climbs back to 44psi, then slowly starts to bleed off. Did this 3 times in a row. My car only acts this way under boost. Could the FPR be going??? BTW it's an adjustable 0-100psi FPR. Any ideas would be appreciated. Thanks

 

Are you still running an FMU?

 

Or a clogged fuel filter

 

Yes I'm still running an FMU. It is set up so it forces all fuel into cylinders at WOT. Vacuum to it is good. I suppose it could be leaking, but I don't see how my pressure could be bleeding off a little from just turning key on from FMU if under vacuum it's letting fuel back into tank anyway.
I have changed the fuel filter twice, blew out the fuel lines and check my injectors and fuel rails for crap - all look good. Thinking I'll check to see if any injectors are leaking, but they are brand new and there is no evidence of leakage on the intake manifold. This is why I'm questioning the FPR, but if you can show me how to test the FMU that would be great so I can rule it in or out. Thanks.

 

I got a aeromotive afpr and its not exactly a high pressision regulator it cant hold fuelpressure if i only turn the ignition on, it drops to zero in apr 20 sec and when i drive the car it doesnt allways respond on small changes in vacuum (havent tried witdh boost yet) like the stock one did.

 

I've used both of Aeromotive's LT1 AFPRs and neither one was worth the rediculous amount they charge for them. I went back to a stock regulator, and the car runs like a champ. Or it did till I blew a head gasket.

 

Yeah, but from what I understand the stock regulator is only good to 60psi and I'm making 90psi at wot

 

That's the FMU closing the fuel line to up the pressure. What kind of fuel pump are you using BTW? Also, what ratio is the FMU calibrated to?

 

I would recommend going to 30# SVO injectors for your set up.

I experienced some of your symptoms when I was running 10 - 11 psi of boost on 24# SVO injectors. Going with the 30's, an adjustable FMU and the LT1 editor made a big difference. I was seeing +/- 90 psi when running the 24's, and was able to crank it down to 65 psi with the 30 #ers. The 30# injectors were flowing more fuel at 65 psi than the 24# injectors were at 90 psi.

Hope this helps

LWM

 

I am running a Bosch in tank Fuel pump, it is new and giving me plenty of fuel. I'm not sure what the ratio of the FMU is, but if I understand I can tell you the adjuster screw is all the way in so as to completely close the fuel line at WOT. Also, I can tell you this car was running perfect, then all of a sudden it was like a spring broke or a diapraghm let go???????? I am looking into possibly upgrading to 30# SVO's and the LT1 edit, but for now I'd be happy to just be running
Thanks again!!