Bozo

I have a 2001 Chevy Cavalier 2.2 5-speed manual. My fuel pump just started to die and at the same time the engine started to run really rough with bad RPM fluctuations, stuttering, generally really bad however with no stalls or backfires. The higher the RPMs are - either when in gear moving, or standing still in neutral - the worse the problem becomes. It actually idles pretty much as it always has with little problem. So I had the pump and the fuel filter replaced, figuring that would solve the problem but it hasn't and if anything is worse than ever. So my questions are:

In order or most likely / first to check, change or repair going down the list to possible but less likely....what should I be looking at? My assumption is that the fuel injectors got screwed-up by whatever killed the pump and they are at the top of the suspect-list. Am I wrong? I guess I will replace the air filter and take a look at the throttle body and clean it. But what else? Spark plugs were just replaced a couple of years ago. I guess it could be the wires? Coils? Anything else?

Thanks for any suggestions.

Bozo

Update. Got a CEL lit up during a test drive and the stuttering, lurching problem has become much worse - even if I hadn't got the code read, I would now say it is definitely misfiring and once today it even downright backfired. Got the codes read at both the Zone and Advance and I have two P0300 - which is totally worthless because of how general and vague it is. One or more cylinders misfiring. Could still be any of the hundred of things from plugs to wires to sensors, valves, injectors, etc....so that didn't help. Came back and changed the air filter - wasn't that dirty. Took off the whole air intake mess so I could get to the throttle body and just for kicks see if it was outrageously dirty. It too was in pretty great shape but I cleaned it off so it shined again.

So - what should I do? Pay some place $100 to hook it up and provide a more specific diagnosis? I just put in the plugs about 2 years ago a d they ought to be in good shape. I pulled the wires off both ends and everything seemed fine. I have two worst-case scenarios. The first is that the people who claim they just took my $600 to put in a brand new AC Delco fuel pump actually put in a BAD one - which will be a real problem dealing with. The second is a compression related failure as in the head gasket going. That's what the auto parts guy says he thinks is most likely for a p0300 non-specific. I hope he is wrong.

Any suggestions or ideas?

mrlee75

I would check for a rodent chewing on some of your wires. Believe me it happens. I just spent 450.00 on the local chevy dealer spending 13 hrs looking for the problem. Then I am told they pulled the engine cover and looked down the side of the engine and low and behold a wire harness had been chewed. I cannot grasp spending 13 hours looking for this!! I will be making sure the dealer knows how I feel about bringing my 2015 Equinox into his place for repairs again.

Bozo

So this problem started JUST as the fuel pump died. Since that day almost 2 months ago, the fuel pump, fuel filter, air filter, oil and oil filter have all been changed and the throttle body was cleaned and none of those things made any difference. The problem has just got worse.

Symptoms -really poor engine running with stuttering and lurching in all gears, all speeds, all rpm ranges. Worst in the morning when just started barely keeps from stalling and just sounds and feels really bad. Check engine light came on for a couple of days with a P0300 - general misfire code but that has gone out at least for now but the problem is as bad as ever.

Going to have to have it diagnosed on some place's computer I guess but what are the most likely causes? O2 sensors? IAC? Fuel injectors, fuel pressure regulator? I really really doubt it is spark / wire / plug - related but I guess they are all on the list too along with the coils. What else? What would be your first 5 suspects?

MCRC007

If you feel its the fuel injectors you can always put them through I few tests. I know its a pain to get them off but if you do you can follow the test methods shown in this video I know it's a little poorly done but check it out!