89 grand prix help

[Roaddog77]

I have an 89 grand prix. starts and stall as soon as you touch the gas. replaced the plugs and wires. checked resistance on injectors. replaced
the fuel pump. checked the fuel regulator. anybody have any ideas?

[richtazz]

What size engine? CEL on? any codes stored? What is your fuel pressure readings? What brand plugs and wires? A little more info please.

[Roaddog77]

Originally Posted by richtazz

What size engine? CEL on? any codes stored? What is your fuel pressure readings? What brand plugs and wires? A little more info please.

engine size is 3.1 fuel pressure is 45 psi. no engine light, ac delco spark plugs, delco wires. no codes stored. i rapped on the pcm nothing changed.
disconnected the tps nothing changed there either.

[Roaddog77]

[quote=Roaddog77]engine size is 3.1 fuel pressure is 45 psi. no engine light, ac delco spark plugs, delco wires. no codes stored. i rapped on the pcm nothing changed. This vehicle has about 125,000 miles on it and i apologize about not posting the engine size just very frustated and wrote the post in a hurry. i am new to this site and apologize to all.

[richtazz]

No apologies necessary. I wasn't beating you up, just getting the specifics so we don't chase ourselves around a big circle. Are you leaving the fuel pressure guage on when it stalls, and if so, do you still have pressure? It sounds like a bad oil pressure sending unit. If the ECM doesn't get a signal from the oil pressure switch after the car has run for 3 sec, it will shut off the fuel pump as a safety measure. During prime, the ECM energizess the fuel pump relay, then when it receives a crank pulse, it switches the ground signal to the oil pressure sender. If no ground signal is present, the fuel pump will shut off. Anothe rsensor that could cause your issue is a bad MAP sensor, but that will usually trip a CEL. The las simple thing to check is for a vacuum leak, but I doubt that's your issue.

[Roaddog77]

Originally Posted by richtazz

No apologies necessary. I wasn't beating you up, just getting the specifics so we don't chase ourselves around a big circle. Are you leaving the fuel pressure guage on when it stalls, and if so, do you still have pressure? It sounds like a bad oil pressure sending unit. If the ECM doesn't get a signal from the oil pressure switch after the car has run for 3 sec, it will shut off the fuel pump as a safety measure. During prime, the ECM energizess the fuel pump relay, then when it receives a crank pulse, it switches the ground signal to the oil pressure sender. If no ground signal is present, the fuel pump will shut off. Anothe rsensor that could cause your issue is a bad MAP sensor, but that will usually trip a CEL. The las simple thing to check is for a vacuum leak, but I doubt that's your issue.

just to update i installed a new oil pressure sending unit. vehicle will idle but still dies once you give it gas. i removed the fuel rail to ohm the injectors again. i disconnected the tps that should put it in a limp mode right? i changed out the pcm with the one in my 90 lumina with 3.1 nothing changed. If i spray carb spray in the throttle body when its running it will run like normal.

[richtazz]

It still sounds like low fuel pressure or a bad TPS. Are you taking readings with the car running? It should drop 3-7psi from the key on/engine off reading, then if you disconnect the vacuum to the FPR, it should spike back up to the key on/engine off reading.

[kenna325is]

I have the same problem with stalling as soon as you touch the gas. My fuel pressure stays normal, though. Someone said crank position sensor?I bought one (cheap) but can't find the old one to replace it. Could this be my problem? and where is it at???

[frogman6042]

had the same problem with my 90 model it was the computor went through everything and after i replaced it the car never ran so good went to salvage yard got two of the best i could find for 20.00 put one in and saved the other for backup no problems yet

[kenna325is]

Where is the computer located at? I still haven't been able to find the problem and I want the damn thing out of my garage!

[frogman6042]

passenger side fender under hood plastic cover that runs down the side remove it and its under there fairly easy to do good luck!!!!!!

[abesafab]

Had similar problems with an 87. Turned out to be a fuel filter. I still don't totally understand how it could be so touchy, but apparently enough crud or water in these filters can have that effect. What the heck, you have changed everything else and they are cheap.