Fuel issue(non Gbody)

[-83MONTESS-]

I know this isnt gbody related but out of all the forums I am on this is the go-to forum. I have a 97 cavalier with the 2.2 and automatic. Car has 95,000 miles on it, I have put 35k since I have owned it. It has ran perfect for the 2 years I have had it but now it's using way too much fuel compared to what it normally does. I have checked for leaks and fine nothing. When I start the car it starts fine, even freezing cold, but I can hear a buzzing for about 20 seconds after startup(im assuming fuel pump here). There is no black smoke coming from the tail pipe and my plugs are dry white which means lean Im lost here. Has anyone had this issue or heard of it? Like I said I understand its not a gbody but I rely on this car for college and work so if it dies on me im SOL! Sorry for the random post but any advice or input is appreciated.

 

[tc1959]

Re: Fuel issue(non G Body)

I know this isn't g body related but out of all the forums I am on this is the go-to forum. I have a 97 cavalier with the 2.2 and automatic. Car has 95,000 miles on it, I have put 35k since I have owned it. It has ran perfect for the 2 years I have had it but now it's using way too much fuel compared to what it normally does. I have checked for leaks and fine nothing. When I start the car it starts fine, even freezing cold, but I can hear a buzzing for about 20 seconds after startup(i'm assuming fuel pump here). There is no black smoke coming from the tail pipe and my plugs are dry white which means lean I'm lost here. Has anyone had this issue or heard of it? Like I said I understand its not a g body but I rely on this car for college and work so if it dies on me i'm SOL! Sorry for the random post but any advice or input is appreciated.

With that kind of mileage I would suspect a slow O2 sensor. Also check to see if the fuel pressure regulator is possibly seeping gas. I have seen the TBI injectors on these leak and drip fuel while running.

 

[-83MONTESS-]

Re: Fuel issue(non G Body)

With that kind of mileage I would suspect a slow O2 sensor. Also check to see if the fuel pressure regulator is possibly seeping gas. I have seen the TBI injectors on these leak and drip fuel while running.

Wouldnt that trigger a check engine light? The check engine light randomly comes on for a few weeks then goes off. It actually just shut off on thursday after being on for a week so it is off now. I notice no difference when driving just a small random miss every now and then but that has always happened. If im all the suddenly running too rich shouldnt the exhaust be darker? Also the plug points to a lean mixture but I am definatley getting worse mileage now. I checked the regulator and all appears fine. I havent taken the vacuum line off it to smell for fuel yet but I will when I get the chance.

 

[tc1959]

Re: Fuel issue(non G Body)

With that kind of mileage I would suspect a slow O2 sensor. Also check to see if the fuel pressure regulator is possibly seeping gas. I have seen the TBI injectors on these leak and drip fuel while running.

Wouldn't that trigger a check engine light? The check engine light randomly comes on for a few weeks then goes off. I notice no difference when driving just a small random miss every now and then but that has always happened. If im all the suddenly running too rich shouldn't the exhaust be darker? Also the plug points to a lean mixture but I am definitely getting worse mileage now. I checked the regulator and all appears fine. I haven't taken the vacuum line off it to smell for fuel yet but I will when I get the chance.

The O2 sensor being lazy usually won't trip the CEL. If you could get your hands on a scan tool you would be able to watch the duty cycle of the sensor, A good one will switch quite rapidly even at idle. Also check the injector for dripping while running and even after you shut the engine off.
If your getting a intermittent CEL you should probably get that figured out first, You might just discover what's causing your fuel consumption issue. It might save you some cash . 8)

 

[-83MONTESS-]

Re: Fuel issue(non G Body)

The O2 sensor being lazy usually won't trip the CEL. If you could get your hands on a scan tool you would be able to watch the duty cycle of the sensor, A good one will switch quite rapidly even at idle. Also check the injector for dripping while running and even after you shut the engine off.

Check the injector for dripping from the fitting or dripping fuel into the port? Im hoping its the 02 because its a simple fix and when I scanned it a year ago it through a code saying there was problems with the 02 but there was no issue. The loud buzzing heard at startup from the fuel pump area isnt a concern? It does go away after 20-30 seconds. Sorry for all the questions.

 

[tc1959]

Re: Fuel issue(non G Body)

The O2 sensor being lazy usually won't trip the CEL. If you could get your hands on a scan tool you would be able to watch the duty cycle of the sensor, A good one will switch quite rapidly even at idle. Also check the injector for dripping while running and even after you shut the engine off.

Check the injector for dripping from the fitting or dripping fuel into the port? I'm hoping its the 02 because its a simple fix and when I scanned it a year ago it through a code saying there was problems with the 02 but there was no issue. The loud buzzing heard at startup from the fuel pump area isn't a concern? It does go away after 20-30 seconds. Sorry for all the questions.

Yes. see if they are dripping from the nozzles. that can be kind of a PITA. More than likely its a O2 problem. Also the 2.2 seems to run better when the throttle body is free of sludge and carbon.

 

[-83MONTESS-]

Ok will do when I get the chance. Thanks for the help I was really hoping I wouldnt have to drop the tank for the fuel pump....the tank I just filled up :shock:

 

[seawolf18]

Pull the vaccum line off the fuel pressure regulator. If there is gas in the line then your regulator is bad. If the CEL light has been coming on, then there should be a code stored in the computer. A lot of your local parts stores have scanners you can use for free. Check for vaccum leaks around the throttle body and lines. Take a can of carb cleaner and spray around the lines and throttle body. If you have a leak the idle will change. If you suspect a weak fuel pump, you can put a fuel pressure gauge on the shrader valve on the fuel rail and check the pressure. It looks like a tire valve stem, with a black screw on cap to protect it. fuel pressure should be Key on, engine not running.........41-47 psi. With engine idling pressure regulator hose connected.........31-44 psi, with pressure regulator hose disconnected........42-50psi. It should hold pressure for hours once you cycle the key on engine off, and the pump does it five second prime.

 

[-83MONTESS-]

I drove the car 104 miles to my college apartment lastnight and everything seemed fine. I watched the fuel gauge and it didnt take anymore than usual :? Im hoping maybe I just had some bad fuel left over from the previous tank I had. My gauge was reading empty but when I filled it up it only took 11.4 gallons----it usually takes 13-14 when its empty. I will keep a close eye on it and report back.