i have 1994 gmc sierra 1500 with 5.7L V-8 truck is dumping fuel to engine chokes truck out at idle but runs good at around 2500 rpm took to shop they noy sure no codes on computer


Asked by Jul 14, 2013 at 06:40 PM about the 1994 GMC Sierra 1500

Question type: Maintenance & Repair

The shop tried: ECU computer, map sensor, coolent temp sensor, ignition module, cap rotors plugs, fuel injector, rebiuld pressure regulator and comprestion test all around 160

9 Answers


Have you checked the timing?


If it's dumping that much fuel the "check engine" or "service engine soon" light should be on and you should have a trouble code for a rich condition from the oxygen sensor. Remember, this is an OBD I vehicle. Your trouble codes will be 2 digits and a different scan tool or paper clip at the ALDL connector must be used to get the codes. Check the fuel pump pressure and volume. Also check the purge valve for the EVAP system. It may be stuck open and allowing raw fuel to be pulled into the intake via the vacuum hose from the charcoal canister. Check the charcoal canister too. If it has gasoline in it, there's your problem. HTH. -Jim

3 of 3 people found this helpful.

pull vacuum hoses and look for wet fuel, that pressure regulator sounds faulty, good at 2500 rpm, not so if m p g is down to about 7 mile per gallon!

1 of 1 people found this helpful.

timeing has been checked and is good truck runs better when main vac hose is pulled gets more air with less restriction. check engine light came on once for a moment then went off and no codes on computer. should have mentioned earlyer fuel is only being dumped in on one side not both u can pull 4 wires off distributor and nothing changes but if u pull the number 3 wire truck tries to run better but u can see injector on one side spraying fuel but not on other side that one is normal did try new injector will have shop try other suggetions thank you

2 of 2 people found this helpful.

That sounds like quite the issue? Have you checked the injector wiring?? They have a hot and are triggered by a negative pulse. A short from the ecm to the injector would spray all the time. would explain why it's one not both. Pull the plug off the bad one and see how it runs on the other one. I would test/check the wiring.


will check that thank you

1 of 1 people found this helpful.

no still not fixed


Are both injectors now firing? As a test switch the connectors on the injectors. Does the "dead" injector now fire? If so it's a wiring problem. If not it's most likely a bad injector. You may have gotten a defective one. I work at NAPA. It happens sometimes. Did you put your old PROM on the new computer? Also, the new computer must have the same service number as the original one. I doubt this is causing the problem but wanted to cover all bases. HTH. -Jim

1 of 1 people found this helpful.

Try finding a buddy's throttle body and puttin on urs. I put a motor in my other truck and when I hooked the two injectors up on the throttle body one side was stuck open. Let me know if that works

1 of 1 people found this helpful.

Your Answer

Sierra 1500

Looking for a Used Sierra 1500 in your area?

CarGurus has 66,572 nationwide Sierra 1500 listings starting at $2,495.


GMC Sierra 1500 Experts

  • #1
  • #2
    John Saffrahn
  • #3
    Glenn Clingenpeel
View All

Related Models For Sale

Used Ford F-150
2,485 Great Deals out of 193,493 listings starting at $799
Used Dodge Ram 1500
361 Great Deals out of 10,777 listings starting at $1,500
Used Toyota Tacoma
569 Great Deals out of 43,788 listings starting at $2,200
Used GMC Yukon
431 Great Deals out of 22,359 listings starting at $1,995
Used Chevrolet Tahoe
689 Great Deals out of 41,244 listings starting at $1,995
Used Chevrolet Camaro
397 Great Deals out of 30,576 listings starting at $2,495
Used Ford Mustang
588 Great Deals out of 36,170 listings starting at $1,800

Used Cars For Sale

2017 GMC Sierra 1500 For Sale
83 Great Deals out of 23,339 listings starting at $23,378
2016 GMC Sierra 1500 For Sale
139 Great Deals out of 4,068 listings starting at $16,990
2015 GMC Sierra 1500 For Sale
157 Great Deals out of 5,198 listings starting at $16,900
2014 GMC Sierra 1500 For Sale
166 Great Deals out of 5,010 listings starting at $13,900
2013 GMC Sierra 1500 For Sale
71 Great Deals out of 2,114 listings starting at $8,450

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.