LT4Camaro

I have a new factory fuel pump, an aeromotive adjustable regulator, and 40lb injectors, im trying to figure out the cause of my fuel pressure problems.

When i am idling, the fuel pressure is around 55psi, and when i really get on the gas it drops down sometimes close to 30psi, it just plunges when i press the gas and stays there until i let off.

When i was on the dyno the car was running lean, really lean, i had to crank the fuel pressure regulator all the way up to get it to be in the good range on the dyno. so the dyno says the car is okay , but when i am idling the car is so rich you can just smell the gas coming out its really rich... and the issue of the pressure dropping so much when i get on the gas..

My question i guess, is should i replace the fuel pump or the regulator?
Get smaller injectors? its a mild motor, lt4 with bolt ons and hot cam.

Another thing is the third hose coming out of the fuel tank , not the feed and supply line, where is that supposed to connect to because i have it plugged and my tank builds up some serious pressure when i drive which i think the vacuum on the tank is causing some problems as well. Should i un-plug that hose? or do i need to hook it up to something else?

Ryan

SS MPSTR

The older versions of the Aeromotive regulators were problematic. I just replaced mine with a newer version and it fixed the problems you described. In reality, you don't even need an adjustible unit - if you have your stock unit, put it back on the car and see if the problem persists.

jOEZ28SS

The third line is for your evap canister in back of the vehicle near your tank.

LT4Camaro

ok where does the evap line connect to under the hood though?

Injuneer

Its always difficult with the 93, because many of the things on the 93 are different, but in the 94+ the third line in the bundle connects to a U-shaped metal tube mid-point near the driver's side of the intake manifold, the tube wraps around the front of the engine under the throttle body, and a hose then connects to the EVAP purge solenoid, on a small bracket on the passenger side of the intake manifold. There is a second line out of the solenoid, that connects to a vacuum nipple on the passenger side of the throttle body.


Shoebox has a diagram, and it indicates the 93 may not have the U-shaped tube.

http://shbox.com/1/1995_evap.jpg

LT4Camaro

oh okay, well the motors a 95 but i stripped that stuff off when i converted the car to a v8, i have all those mentioned ports just plugged and no purge solenoid, i guess i will be picking up a purge solenoid.... will this affect engine performance or fuel pressure though?

Injuneer

No. That's not the cause of your fuel pressure problem.

You got what I believe may be the right answer from SS MPSTR, but you appear to have ignored it. The Aeromotive LT1 fuel pressure regulators are not reliable at all.