I have a 1994 gmc Sierra 1500 5.7L. It is running like crap. It is rough at idle and stall when you put it in gear. I've rebuild the throttle body and it still won't stay running.

Asked by Nov 10, 2015 at 09:39 PM about the 1994 GMC Sierra 1500 C1500 SL Standard Cab LB

Question type: Maintenance & Repair

My boyfriend thinks its the o2 sensor I
honestly thinks its the spark plugs
and cap and rotor and the wires. Need
help

3 Answers

86,355

If it has not had a recent tuneup then that is the place to start.

3 of 3 people found this helpful.

All to often people jump to 02 sensors as a problem when more often they are not the culprit. o2 sensors will never cause a no-start, and if bad the worse case is an off fuel/air trim. I agree with FoR, that's the place to start since it is not OBDII to get a code. And make sure the catalytic converter is not plugged

3 of 3 people found this helpful.
200

94 GMC sierra with a 5.7L.... Bad ground, probably, or dead short, maybe, somewhere in either the wiring harness or instrument panel..... It's a bitch to find it, and tossing parts at it will sometimes "accidently" fix the problem for you. But only if you changed the sensor or other part that just happened to be the one with poor ground connection..... Could also be a dead short in something causing power to drain through the short, but only when a signal is received by the ECM from one of the sensors that winds up grounding out the signal that normally controls the Idle Air Control valve, or the fuel injection circuits..... I ain't a mechanic, but I've been trying to chase down that same problem now for almost three weeks..... Problem started with the 305 that was in the truck, came right back up after dropping a newly rebuilt 350 in place, along with virtually all new sensors and valves from the start.... There is either a dead short, or a piss poor ground on "something" or in some part of the wiring harness causing the problem in thousands of GMC trucks. If all the questions regarding the same identical problem is any indication. It's going to be an easy, and cheap, fix if you can find it. The headache comes in trying to find it.

Your Answer

Sierra 1500

Looking for a Used Sierra 1500 in your area?

CarGurus has 64,898 nationwide Sierra 1500 listings starting at $999.

ZIP:

GMC Sierra 1500 Experts

  • #1
    dragonflyoffshore
    Reputation
    5,460
  • #2
    John Saffrahn
    Reputation
    3,780
  • #3
    Glenn Clingenpeel
    Reputation
    3,470
View All

Related Models For Sale

Used Ford F-150
3,290 Great Deals out of 224,485 listings starting at $1,200
Used Dodge Ram 1500
413 Great Deals out of 11,096 listings starting at $1,500
Used Toyota Tacoma
721 Great Deals out of 45,869 listings starting at $2,500
Used GMC Yukon
614 Great Deals out of 20,554 listings starting at $2,500
Used Chevrolet Tahoe
828 Great Deals out of 42,144 listings starting at $1,987
Used Chevrolet Camaro
443 Great Deals out of 31,893 listings starting at $1,450

Used Cars For Sale

2018 GMC Sierra 1500 For Sale
3 Great Deals out of 26,504 listings starting at $23,419
2017 GMC Sierra 1500 For Sale
86 Great Deals out of 10,675 listings starting at $20,369
2016 GMC Sierra 1500 For Sale
173 Great Deals out of 4,105 listings starting at $16,404
2015 GMC Sierra 1500 For Sale
192 Great Deals out of 5,659 listings starting at $14,995
2014 GMC Sierra 1500 For Sale
221 Great Deals out of 5,002 listings starting at $9,900

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.