dwhipper61

Hello I have an 89 Convertible with auto trans. Have been driving it for about 6 months. On acceleration it would bog but eventually reach highway speed if I very lightly accelerated. The MPG gauge on the dash did not work. There was no check engine light. I borrowed an mt2500 and it showed a code 42 electronic spark timing and then was unable to communicate with ECM. I tried several times and still unable to communicate.

I replaced the ECM with one from Oreillys. It took several seconds of cranking for car to start. It eventually started and I drove it for several miles and stopped and started car multiple times. The bogging problem was gone.....the MPG gauge was working and car was running great. I thought my problems were solved.

Car sat for a week and I wanted to take it out today. I had to crank for several minutes before it would start. Sometimes it would start and immediately die, sometimes it would start fine, and sometimes it would not start at all. I replaced the ignition module with a new one from Autozone...no change.

I checked the codes with the mt2500,,,there are no codes. I pulled two spark plugs and I have good spark. Car cranks and cranks....I smell gas then I see gas dripping from mufflers. I decided to give up for the night and ask you guys for suggestions. I appreciate any and all suggestions.

THANKS

stew86MCSS396

Welp if fuel is dripping out the tailpipe, I'd be looking at the fuel pressure regulator vacuum hose for fuel. If the diaphragm is ruptured, pressurized fuel will leak into the plenum. If FPR checks out, move on to fuel pressure. Quick leak down may indicate leaking injectors. Since you're not throwing a code but you own a MT2500, how does the coolant temperature sensor compare to the ambient air? A below freezing CTS will command a richer startup AFR.

Also...with that much fuel coming out the exhaust, good idea to check if there's any fuel in the oil.

jv9999

If fuel is dripping from the exhaust, the oil is definitely diluted. Don't run it. As Stew said, fuel pressure regulator or injectors. If the injectors are original, it's time for them to go either way. Get or borrow a FP gauge if you don't have one.

dwhipper61

THANKS for the comments. I borrowed a fuel pressure test kit from Autozone.
I hooked up the gauge to the schrader valve, pressure was 0
Turned key to run but did not crank engine pressure jumped to 43 and almost immediately went back to zero
Cranked engine for a few seconds pressure went back to 43 and then back to zero as soon as I stopped cranking.

I also checked the oil. It does have a gasoline smell and is over full.
The coolant temp is 25C and the start clnt is 25C

I'm guessing this means I need a new fuel pressure regulator?

THANK YOU

stew86MCSS396

Only if there's fuel/smell of fuel in the vacuum line going to the fuel pressure regulator I'd suspect that is the bad component.

dwhipper61

UPDATE. Problem solved. Incorrect ECM from Oriellys.

Changed oil and spark plugs. Installed the correct ECM and car is running great.