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Old pump was rotted out and went bad. I replaced the pump and maybe some crud got into it and clogged up the filter again. I'm going to change the filter and check the fuel pressure and then try to change the fuel regulator
I found it..
"Fuel pressure should be around 35-40 psi with ignition on. Idle should be around 45 or so, and when you rev it it should go up to about 50-55 psi."
Hope that is correct.
Seems like fuel is good enough to be ruled out. Problems may be in harness. What caused you to originally change ECM and throttle body?
Have you checked for open circuits and continuity in loom? I worked on a few weird problems that boiled down to problem in loom and pigtails (chewed insulation, pins being bent, disimilar metals causing corrosion, etc). Ruling out the harness with a multimeter might be a good place to start making sure all the things work together.
Seems like fuel is good enough to be ruled out. Problems may be in harness. What caused you to originally change ECM and throttle body?
Have you checked for open circuits and continuity in loom? I worked on a few weird problems that boiled down to problem in loom and pigtails (chewed insulation, pins being bent, disimilar metals causing corrosion, etc). Ruling out the harness with a multimeter might be a good place to start making sure all the things work together.
Just thought ECM was not sending correct ignition signals and same with the throttle body. Just looking to eliminate obvious components.
Any instructions on to check continuity of the loom?
I am not an electrician but the following is what I usually do.
I start by inspecting my grounds making sure they are really nice. Sometime this is enough.
Next, find your wiring diagram and disconnect all plugs of suspected circuits (ECM, throttle body and fuel). Check continuity from end to end. Check continuity of wire to ground. If you have continuity to ground, repair the short. If you do not have continuity end to end, repair broken wire(s).
If all this checks out, plug it all in and look at suspected components. I’m a big fan of back probing wires with T-pin sewing needles, while the car is running. This will let you see what is happening with the different sensors.
In regards to throttle body and ECM, the TPS connector on this car is known to have corrosion due to the pins being a dissimilar metal. This can cause some high resistance and low corresponding signal voltage to ECM. Someone correct me if I am wrong, but I believe there was a TSB for this.
Ruling out the loom is time consuming but free. If it’s bad or borderline new parts will only frustrate you. Good luck and let us know what you find.
Last edited by nunger1330; Mar 21, 2024 at 01:52 AM.
While working on the ignition problems i decided to tackle and water leak i have at the bottom of the water tower. The leak turned out to be the heater hose so i removed the intake manifold. While removing the gas lines i noticed rust in the lines. pulled and injector and lookie here! So now I'm cleaning the fuel lines, injectors and intake manifold. I also noticed rust in the fuel regulator which could all contribute to my problems. I will retest after all this work is done and report. Thanks for all the help.
Well.. here is update. Cleaned the intake and all injectors. Tested each injector and all are good. Cleaned and Tested the fuel regulator with a vacuum and opened and closed properly. Changed the fuel filter. The old filter had pieces of rust coming out of it. Drove the car and great for about 1 hour then started to get hesitation. Hooked up a fuel gauge and taped it to the window to get a better understanding on what is going on. I ran a steady 39 to 44 psi and then suddenly the gauge started to fluctuate between 35 and 40 back and forth even at idle. Suddenly it dropped to 10 psi and the would not accelerate. So I think I found the problem. I replaced the fuel pump at the start of all this so I'm thinking either a bad pump or some debris is clogging the pump and or the filter. Any thoughts. I would hate to do the fuel pump again. Thanks
Finally finished the fuel system. Removed the fuel tank and found lots of rusty fine power. the screen on the fuel pump had about 1/8 inch caked on goo. the fuel filter was also clogged. So i did the muriatic acid soak and got rid of almost all the rust. Flushed the tank about 10 times and then coated the tank with KBS tank sealer. I also updated the one way return valve with a new aluminum valve. Waited 5 days for it to cure properly. Must say it looks like a new tank. Cleaned the fuel pump and screen. Installed a new fuel filter. Cleaned all the Injectors and cleaned the intake manifold. I'm getting 50 psi on the fuel rail now. Runs like a champ. No more hesitation or stalling. I hope this helps anybody else with the same type of issues.
Thanks for everyone's help.
