Problem help/suggestions

[ChevyDude84]

Ok guys, it looks like the truck wants to act up on me so close to summer (grrrr) anyway I am having the following issues and need some advice on how to proceed.

1.) Oxygen sensors ( I have replaced both the sets before and after cats but they keep failing CEL comes on randomly 1-2 months later without fail typical 0301 something oxygen sensor code). What is causing these sensors to keep failing? I am using the recommended Bosch oxygen sensors... any help on this would be appreciated.

2.) Gas smell ( may be related to problem 1 above, but I am not sure) I have noticed a strong gas smell from the truck lately... its start to become apparent in the cab now starting to get a little worried... exhaust system is stock and the cats are still on. What weird is the gas smell doesn't seem to be coming from just one area, I can usually smell it on both sides of the truck. Mostly towards the bed area... but some times it will creep upward.

What all do I need to check or is there a common problem with this? starting to get a little worried since the smell is getting worse. Smells like straight unburnt gas, (not a rotten smell).


I appreciate you guys for reading this, please shoot any suggestions.

 

[SAATR]

P0301 is a cylinder 1 misfire code, so if you could give the exact code that you are getting it would be helpful. The gas smell is very likely a leak in the evaporative emissions line coming from the tank to the charcoal canister under the hood, or from some part of that system. I would double and triple check all lines from the tank to the engine compartment for leaks and rubbed spots, as I had one of these lines rub through in the engine compartment causing a similar issue. Fix them ASAP, as any fuel or fuel vapor leak is a potential fire or explosion hazard.

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[Rusty Nail]

Info regarding the truck may prove useful, just sayin. If you have 4) O2 sensors and are posting in an OBS forum, I assume it is a '96-'98?
I know that an overdue oil change WILL set an oxygen sensor CEL on SOME trucks, (mine being one of them, a '97 v-6).
Regarding the fuel smell my thoughts immediately go to fuel pressure regulator, but I am not familiar enough with them on Vortec engines to speak of them freely. I only guess that a bad gas cap would set a different code and now I want to look at the hose connections on top of the gas tank...

 

[ChevyDude84]

Sorry, its a 98 5.7 4x4... (early morning pre coffee post).

I will check all the lines and the charcoal canister, am I looking for obvious leaking of gas or broken lines in general? I haven't seen any leaks on the ground from gasoline... also where exactly is the fuel pressure regulator? could it be a fuel filter or fuel pump?

 

[someotherguy]

Seeing that you are from MO I wouldn't write off the possibility of a fuel tank leak due to rust on top, or even at the bottom, where the plastic shield covers it. Doesn't take much of a leak for you to smell it, but not see a puddle on the ground. All it takes is enough to make it a little wet.

Closely inspect all the fuel hard lines along the frame rails. A '98 won't have metal lines at the sender as it has the plastic sender/pump assembly with the quick-connects instead of flare fittings, but they go to metal as soon as they hit the frame.

Richard

 

[SAATR]

Regulator is in the intake, so it shouldn't cause a smell. If it's the Evap lines you won't see a liquid leak, just vapor. You have to look closely for rub marks or cracks all the way into the engine compartment.

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[Big98z71]

I also have a 98, about a month ago I had the gas smell, my tank had a small pin hole in the seam. Not hard at all to swap out. Also mine didn't leak until I hit the 345000 mile mark. Even after using it the last 8 years feeding round bales everyday in the winter

 

[ChevyDude84]

Okay guys got a little update: I checked all the lines up to the engine compartment I did not see any rub marks or broken/frayed lines... but they did look pretty rusted in some spots... I got the CEL scanned and it pulled a code of P0430 "Damaged Catalytic connector." This is different from the regular CEL's i got for low voltage for the oxygen sensors in the past. From what I have been reading (and correct me if I am wrong) this is a common code for cat failure. Would that also explain the gas smell?

 

[SAATR]

That code could be caused by a faulty sensor, exhaust leak upstream of the sensor or cat, or cat failure. Check for exhaust leaks first. If none are present you would next check circuit integrity by verifying proper voltage to the sensor, and then shorting the signal wire to the reference signal to see if you get a "circuit high voltage"code. If that checks out, and it throws a low voltage code when disconnected, then I would check the terminals at the connector for damage. If all that checks out, and the O2 is new, then the cat is probably faulty. A faulty cat will not cause a fuel smell, however.

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[98_k1500]

Throw some non-foulers in the rear o2 sensors and you can chop the cats off and not worry about it That bein said, its not gonna cause a gas smell, and idk what you have to do to pass emissions there.