Hello, I have a '92 z28 305 TPI. I've run in to a problem ind I'm hoping that it is a quick (and cheap) fix.

3 days ago I made a short trip of 31 miles, took about 30 min. The drive there was fine, but when I was leaving, a co-worker wanted to compare rides. We pulled them next to each other, checked them out, and revved up the motors. On the way home I noticed that my gas had dropped kind of fast. When I got out of the car there was a distinct gas odor.

2 days later (yesterday) I pulled out my car to make the trip again. As i got out of my car to close the garage door I smelled a strong gas odor. Not thinking anything of it at that time I got onto the highway. About a third of the way there a semi started to run me off the road. I gave the throttle a little push and pulled ahead. As I did this though, I watched my fuel gauge go from quarter tank to just above empty (stunned me almost as much as the aforementioned semi). The rest of the way to work I watched the gauge drop at a fairly steady rate. The gas odor was still there when I arrived.

After work I put in enough gas to read just below quarter tank. The fuel gauge was pushing past empty when I got home. Again, this is only about 31 miles and 30 minutes. And once again the gas smell was there. I looked, felt, and smelt around my car, and could see no signs of leakage. The smell led me to the front of the car. Looking and feeling around the motor I could find no signs of a leak, but there were gurgling/boiling noises coming from the passenger side of the engine bay.

This morning I tried poking around the motor again and found that my oil was low. I filled the oil and ran the engine. There appeared to be extra noise on the passenger side (not fluid, it was the sound of something electronic or mechanical). I started the 'maro up and realized that there was no gas odor. I drove to the gas station and put in enough to read just past quarter tank. I drove to work and when I arrived I was at just under a quarter. There was still no odor, and I thought my problems were solved.

I left work and started my car, and there was the smell again. For the first 1/3 of the trip back I did not notice a huge drop in the fuel. At on point I had to brake as I was coming around a turn on the highway. After this my fuel started to drop at that steady, fairly ridiculous rate, though not as much as the initial day. As I got out of my car at home, there was not much of an odor. (I have a manual fan switch, and it was off on the way to work this day)

Also, a few days before this started I put in 91 octane, I normally use 89. When I filled up the other times after the problem started I used 87 (knew it was going to disappear anyways so I went cheap). And my check engine light does come on after driving for awhile, but if I turn the car off the light goes off and doesn't come back on until I am driving for another awhile.

Sorry about the brutally long post, but I'm not sure what is causing the problem and I wanted to make sure that I listed any little possible thing. I am going to drive a little bit tomorrow to get the check engine light on, then go to Checker to have them scan it.

I did search online, and the responder on this sight seems to of had the same symptoms. Not sure if any of the solutions are the same though, because I didn't notice any fuel leaking from the line, and the odor is in the front. The link: http://wiki.answers.com/Q/Why_would_...le_its_running

Any help is greatly appreciated. Does anyone know of fuel consumption being so drastically affected by low oil, or maybe something is getting knocked loose like when I went around that turn? Like I said I am completely stumped, and am on the verge of taking the 'maro to a shop. Something I would hate to do, but it's kind of a serious problem, and I still have to drive out to that site for another week and a half. Thanks again.

 

The light is probably your O2 sensor telling you that you're running rich.

With that much consumption, it would do you well to smell your oil and make sure it doesn't smell like gas.

Check your fuel pressure. See how high it goes and how well it holds. You may have a stuck open injector or two.

Tune-ups are always a good idea if one hasn't been done for a while.

At the very least, you should pull each plug individually and give 'em a good look-see. Plug reading can tell you a lot about what the engine is doing.

 

Thanks for the reply. I will be sure to pick up a fuel pressure gauge at Checker. Stupid question: Do stuck injectors have to be replaced, or would I just have to clean/tweak them? I also heard that the problem could be with a faulty fuel pressure regulator, any thoughts on this?

 

One other thing... The check engine light has been coming on intermittently for awhile before this problem, could it be from a faulty O2 sensor? Is it possible that my O2 sensor just got worse until eventually it told my car I was running too lean, so my car started spitting ridiculous ammounts of gas into the motor?

I'm headed up to checker in a little bit, just wanted to know if this was possible before I went so that maybe if the code matched this scenario I would only have to change out the sensor.

 

Get an ohm meter and measure the resistance of each fuel injector. I'd bet that one of em' is bad.

 

ohm meter - added to shopping list.
Thanks

 

Okay, so I bought a scanner and an oxygen sensor (even if this problem wasn't the O2 sensor, I knew I needed one anyways).

She is throwing code 32, which is defined as:

 

Code 32 as defined by my 92 Helm's factory service manual is:

EGR circuit

A search on here should net you some troubleshooting procedures.

Basically though your ECM is telling you that the circuit is bad. Whether it be the solenoid (most likely) or even the valve itself.

 

I did a search, and I do seem to be having similar symptoms as others with EGR issues, except for the massive gas consumption part. Would a faulty EGR solenoid or valve cause the fuel dump, or is this a seperate problem?

I will be checking the fuel injecter voltages after work tomorrow, as well as the EGR parts. With the EGR solenoid, is that tested for voltage as well?

 

Fuel dumping at that rate that you can actually notice it is pretty extreme. I would first check for leaks externally. Then i would pull the vacuum line off the fuel pressure regulator do see if the diaphragm ruptured and is leaking fuel directly into the intake. Lastly do a fuel pressure test to see how long pressure holds after the cars been shut off to detect fuel injector leaks. Honestly i wouldnt drive it untill this problem gets solved as if you have a leak it could start a fire pretty easily if its in the wrong place. I know i had a problem on a mechanical fuel pump i replaced and the fittings that came with it to adapt it to an AN line were wrong, didn't seal, and was spraying fuel out right onto the header! That could have been a very bad problem if i didn't stop and check things out.

 

this fuel usage is it constant or only at speed? i mean the amounts you are describing would have your eyes watering and coughing up a lung....

another way to check to see if you are actually running that rich would be to drive the car around bringing it up to temp try to keep RPMs around 2000 then with a infra red pyrometer measure the inlet and outlet of the cat immediately after stopping the car temp difference shouldn't be more that 200-220deg between them any more is a good sign that the cat is burning up a lot of extra hydrocarbons (engine is rich)


also the smell coming from the driver side right behind the headlight would be the charcoal canister part of the emissions system

have you tried removing the fuel cap after you noticed the gauge dropping maybe pressure build up?

the gauge in mine has always been odd... stays above a half way to long then once it hits 1/4 you best be on your way to get gas because it seems to drop off pretty fast but i found removing the gas cap will bring the gauge back up maybe 1/8 from where ever it was after driving to the gas station

 

sounds to me like your're building up too much pressure in the tank and its all purging out your charcoal canister, had any exhaust work done recently? also, if the engine was burning off THAT much fuel it'd be burying the engine in gas, IF it even would run, it'd be pushing THICK black smoke out the pipes, maybe even enough to hydro lock it. no i think there is either an external leak or too much pressure in the tank and purging it once the purge solenoid opens

 

Okay, so I will definately be checking the vacuum to the fuel pressure regulator. I will have to pick up a fuel pressure gauge as well.

The fuel usage was most extreme when I passed a semi on the highway, that is when it dropped a quarter tank just for pulling in front. At speed (mostly highway) I will use almost a quarter of a tank in 30 minutes. I was driving around tow to a few different auto parts stores yesterday, and she still dropped in fuel at too fast of a rate.

In regards to the pressure build-up; I have noticed that in the past few days when I get into my car the fuel gauge will be higher than when I left it. When I start the car the gauge will drop back down to where it was. Yesterday I bought gas twice, and both times the gas cap was "vacuumed in" a bit. I had to turn the cap harder to get it off, and I could hear the pressure relief when the cap did come off. Would this be a clogged fuel line? If so, would some fuel injector cleaner in the tank before I fill up do the trick, or would the solution be more intricate? If it is purging into the burn can, would replacing the filter or other burn can component be the answer?

I have not seen any black smoke coming from my car, at speed or otherwise. Most of the auto parts employees told me that a stuck injector was a strong possibility. If it is a stuck fuel injector would there be smoke? Would a stuck injector have to be replaced, or is there a way "fix" it?

I have checked for leaks, and I can not find any. I do not see or feel any in the fuel line from the tank to the motor, and the smell always leads me to the front of the car. I could be missing it, but I have been searching for leaks, because that was my initial fear.

Thanks for all the feedback.

 

If the EGR is stuck open it'll make the computer think it's lean causing it to dump more fuel.
I still think you have an injector issue.

Your gas tank should have a check valve on a vent line near the rear drivers wheel. That's supposed to release excess pressures from the tank. If it's not doing that then you can replace it or get a vented gas cap.

 

but how much extra fuel can the computer actually add 10%? probably not enough to cause what he is discribing

 

No not likely to cause what he's describing.

Just giving a possible explanation regarding the EGR system. His problem may be two-fold. The EGR could be adding to the possible injector issue.

 

Okay, I'm probably not going to be able to buy anything else until Fri. (payday). I was wondering if there was any tips for driving with bad or possibly suck injectors without aggrivating the problem too much. I did have that one successful drive...

Also, I wanted to install the new O2 sensor, but I am thinking that I should wait until I cure the 'maro. I don't want to foul up the new sensor with the crazy fuel dumping.

I still have to take my ohm tester to the injectors, check EGR equipment, ect. Hoping to have the time tomorrow, work ran over today...