Does anyone what may be the cause for rich gas mixture on my 96 GMC Jimmy? Smelly exhaust.?

Question

I have a 1996 GMC Jimmy 4DR 4x4 with a 4.6L Vortec.

The car seems to be running too rich. The exhaust smells of unburned gas and the idle is a little rough (but doesn't die).

The car seems to still have full power and have no problem getting around. I've tried changing the PGR valve (located in the center front of the engine) and also the engine computer (located on the left side of the engine bay). I've tried changing plugs also. Nothing.

I've heard these are common for these cars and it's kind of a cop-out on GMs side for not recalling.

But what can be causing this? Any good info would be appreciated and also sources if you have them. Thank you!

Answer 1

I agree with Ron B on the CFI failure, but it doesn't always cause a check engine light. Normally, if the CFI has a leak from a poppet, you would more than likely have a misfire or rich code. Depending on where the leak is, in the line, the fuel pressure regulator, or the main injector, it would also be hard to start. If you already have a code for running rich, I doubt the oxygen sensor is the problem, since it is what would set the code, because that is what it is designed to do. If you are running rich, the oxygen sensor is the messenger, and seems to be doing its job. This sounds like a leak while running, as opposed to a leak during startup and fuel delivery so I agree with the probability of a cracked injector line or poppet. You can pull all of the plugs out and keep them in the order you pulled them out. If any are gas fouled, it will most likely be on one bank, or one or two plugs on the same bank. That would be a tell-tale sign that it might be worth pulling the upper plenum and taking a peek inside.

Answer 2

Dan: you already know the clarification that your Gmc Jimmy ninety six four wheelchronic won't commence that's some thing to do with the automobile's On Board laptop could have an crack of course if no longer that there is yet another non-obligatory call the Gmc /sidestep maintenance& maintenance additionally ask them for track Up provider it relatively is the superb one answer

Answer 3

One common problem with the 4.3L engine was the injector to nozzle lines inside the engine intake would crack and spray fuel into the intake causing a rich condition and rough idle. This should be accompanied by a check engine light for a rich exhaust. You need to go to a qualified mechanic and have the problem diagnosed>

Answer 4

try adding split fire type spark plugs,and a k&n air filter,might need to up grade spark plug wiring to compensate,change fuel filter,and last but not least,buy a good type of fuel injector cleaner and add with a gas tank fill up!hope this helps good luck!u did not say if check engine light was on?

Answer 5

Check the O2 sensor

Answer 6

try changing the 02 sensor.