QuestionI have a 1997 gmc sierra v8 1500. recently it stalls at stop lights as I start to go or just as I am putting initial pressure on the gas pedal.Even asI pull out the drive way.
It is also losing major power ghoing down the road, not just at inclines. I can hear clunking under the hood when I put the pedal to the floor. This has been going on for 3 weeks now. I had a mechanic say that the o2 sensor showed up on his computer, however it made no difference in the performance after he replaced it with a new one. Another mechanic unclogged the exhaust and catalyc converter, still no change. I put a new fuel pump in last year, changed the filter 2 weeks ago, and put new plugs and wires in 2weeks ago too. Do you have any ideas?
AnswerBy WHAT method did he UNCLOG the converter and exhaust ?
You have 2 tests to perform:
1. Put an external fuel pump gage on the fuel system to verify proper fuel pressure.
Just because you replaced it 2 years ago does not guarantee that it still working. I lost count of how many parts that failed within days or weeks after installation over the years.
2. perform a BACK PRESSURE test on the exhaust system by putting a PRESSURE TESTER in the OXYGEN SENSOR hole and see if you have over 1 and 3/4 lbs of BACK PRESSURE. If you DO, Your exhaust is restricted.
3. Run a COMPRESSION TEST on ALL cylinders to be sure that they are ALL within factory specifications.
Your CLUNKING noise has me concerned, Depending upon what TYPE of noise could mean a minor or major problem. I would suggest that you have a professional technician have a listen, Since it is quite impossible for me to hear it from here.
I know your looking for an EASY answer, But without GUESSING, There is none. Testing per above is your next step besides having the noise heard.
autohelp
