I have a 94 Z-28. Everytime I push the gas any decent amount it hesitates then all of a sudden it will take off. Also Ive noticed that it smelt like it was running very rich on fuel and while I was talking to one of my friends at autozone he noticed that I had fuel spitting out of my exhaust, we checked my oil and it too also smelled like gasoline and was very close to being over full. I was wondering what all of you thought the diagnosis would be and if the two problems were related.....As of right now my only guess would be that it is the fuel pressure regulator and that Im getting so much fuel in the motor that the pistons cant compress it and that it is seeping around my rings getting into my oil
Any input would be appreciated

 

i wouldnt run it much. your going to wash out your cylinder walls if you already havent. your obviously flooding BAD. the very first thing you should check is your COOLANT TEMP SENSOR. that is one of the very few things that will cause you to run that rich. and most common. check there....

 

As far as the temp sensor goes. It can't make any engine dump that much fuel. Think about it. If it's screwed up it wouldn't make it any richer than when it is first started up from dead cold. At first start, the engine is as cold as it will get. The PCM is in enrichment mode until it gets hot. Yes if the temp sensor is bad, it will run rich. But not nearly enough to dump fuel that bad.

You either have a leaking injector(s) or fuel pressure regulator.

 

i second the fpr. give the vacuum line to it a sniff.

 

i guess when my car ran so rich that it fouled a set of plugs in a matter of seconds and proceeded to die and never restart, i was imagining things when i scanned the car and the cts was reading -40. and it was 80 degrees outside. but i guess i must have been dreaming. my bad. just think about how much fuel it was dumping. as far as the fuel pressure regulator pull the vac line off of it, if there is fuel there its bad, it means the diphragm is busted. but i doubt that that is your problem. becuase your injectors have to fire to let fuel into the cylinder, which is why its most likely an electrical problem. that is unless all 8 are leaky, but i highly doubt that.

 

A fuel pressure test gauge connected to the fuel rail would show if you have a bad regulator and also show if you have an injector(s) leaking down.

 

As far as the ECT sensor goes I just replaced that about two weeks ago and it didn't fix my problem and now Im pretty sure that its the FPR because the vac hose does smell like gasoline and I dont think thats too good? It could be a combination of that and a leaky injector but I havent been able to get ahold of a test gauge to find out...I read on another web page that I could pull out my injectors attached to the fuel rail and turn the key on and if they are putting out fuel they're leaking but I'm not sure if that would screw up anything else in the process.....

 

The PCM will set A/F ratios as rich as 4:1 on cold start. That will POUR fuel into the engine.

Have you scanned it to see what the PCM is reading for coolant temp? Maybe the problem is a short in the wire, and not the sensor itself. You did change the sensor in the water pump housing, right?

Have you checked the plugs for signs of running rich? The leaking fuel pressure regulator will tend to dump the fuel on the passenger side, in the back, where the vacuum connection is located.

You can pull the fuel rails, injectors intact, and turn the key on to pressure the system. It will not harm anything doing that, as long as the engine is cool, and you don't try and start it and spray fuel all over everything. The pressure test is the best place to start, because a leaking regulator or a leaking injector will allow the pressure to drop rapidly.

 

as injuneer said, check the wiring. if i remember correctly if the wire is unplugged or broken it will give the pcm the same reading as if it is extremely cold outside....i bet your problem lies in the wiring. usually a problem like this is cause by something silly like that.

 

Yeah but even If I did have some faulty wiring my vac hoes off of the fpr still shouldnt be smelling like fuel...right?

 

the vac hose may smell like fuel but if you dont have any liquid fuel coming out of the vac hose i wouldnt think that your fpr is bad. take the vac line off and see if any fuel comes out of the fpr while its running, if there isnt any i HIGHLY doubt it is the cause of your problem. like i said before you would have to have at least one injector stuck wide open for the fpr to cause your problem. im almost willing to bet money on it that if you put a SCANNER on your car and read the cts output you will see that there is something wrong with that circuit...

 

actually...I believe you guys are right...I looked to see if there was any fuel coming out of the vac line while it was running and there wasn't any then I pulled the plug in off the cts and it didn't seem to run any different...what I dont know is how I havent fouled my plugs and stuff if its sending it to the computer that its running that cold lol....Im gonna take it out to the place where I bought it from and make him hook it up to his scanner for free....I think that he could at least do that for me....I'll let you know as soon as I find out...

I was also gonna ask you guys what the chances were that its what they call the pigtail or the plug in thing that goes to that sensor that has gone bad....im hoping thats the case...but for some reason I dont feel that Im that lucky....

 

If you have fuel coming out of your exhaust and in your oil DO NOT DRIVE the car. Tow it. When you figure out what's wrong with the cts circuit change the plugs and the oil before you drive it anywhere. You are at a SEVERE risk of spinning a bearing or causing internal engine damage.

 

Quoted for truth - I drove only 80 MILES on my engine with about 1-2 full quarts of gas that washed passed the cylinder and got in the oil. 80 miles is all it took to cause $1200 in machine work when I had two main bearing failures. And I wasn't even running so rich to have gas coming out my tailpipes...