scotth48

My 1993 has a slightly rough idle when I was checking fuel pressure as as the neddle on the gauge was fluttering a couple of pounds and not steady. I pulled one spark plug and it looked great. They have about 4000 miles on them. Tonight after dark I checked the wires with water and no arching. It did seem a little smother. Will recheck pressure tomorrow.
Next step to change fuel filter and clean the K&N air filter or replace with paper from NAPA. Haven't really sold on the k&n.
One accomplishment was fixing the second headlight with new pucks in the gear. It was just like the other one all pucks were like sawdust. Gear was fine. Headlight is plastic lens and yellowing some. Would like to replace with glass maybe led. Nice not to hear that clicking on the light rotating.

Brenden Rogers

The fuel pressure should be steady and hold without fluctuation. Does the car hold psi after the fuel pump primes the engine, without the engine running? Does the vacuum line on your fuel pressure regulator smell like gasoline?

scotth48

After installing the adjustable fpr many years ago it never held pressure. In fact I sent it back for replacement but the next one did the same so I lived with it going to 0 after key was off. But now the pressure on the gauge bounces wildly from 39-48 psi. My neighbor is a gm mechanic said it was probably the regulator or the pump. Injectors just been returned from fic to be checked out.

Brenden Rogers

I have a feeling you might have a failing fuel pump. I don't think you're so unlucky that you got 2 faulty fuel pressure regulator in a row. I inserted a YouTube video that goes into detail on how to diagnose the problem and fix it.

scotth48

I checked it just now and the car idled great and fuel pressure was ok. Intermittent pump?? Will check it after it has a longer time to run.

aklim

Clamp off the return line after it pressurizes and see if it holds. If it doesn't the problem is somewhere else. If it does, it is the regulator.

scotth48

If the check valve is bad in the pump it will leak back too. Pressure has always dropped to zereo using the adjustable fpr.
I am more inclined to believe that once the pump gets warmed up that it is not working properly. The two other times I checked it the engine was running rough and had the fluctuating and was after having been driven. Yesterday the engine was cold and only ran it for about 15 minutes. Not worried so much about pressure holding after it is off but the 10 point fluctuation that is taking place. When the engine was cold it ran smooth. I had the wrench and allen wrench sitting on the plenum and stayed there. When it was rough it would move around.
I have both a 190l and the 255l hp walboro pumps and jit on hand. Want to check pressure after I drive it 20-30 miles. If it ryns rough I'll put one in. Delphi FE01111 is what is currentl installed.

aklim

Maybe so but we need to take it step by step so we are not doing things that are meaningless. Make sure which end of the circuit it is in. If the regulator leaks, nothing we can do but try something new. Maybe a stock regulator since this one doesn't really do much.

scotth48

Checked aeromotive website about why regulator won't hold pressue after shut down. It may or maynot hold pressure after shutdown as it is made for performance. It was a EPA requirement for stock pumps to hold pressure for 30 minutes. Only means you may have a longer crank time or wait a second for pressure to build before starting.