I recently purchased a 1990 GMC 1500. 5.7 L 350 TBI. When i bought it, it needed a starter and battery to get her going, but thats when the problems began. I got a check engine light, and after checking the codes it was for rich exhaust. I changed out the 02 sensor, and this went away. No im getting no codes but still having problems. The number one problem being when i start it as soon as i take my foot off the gas to let it idle, it stalls right away. Had a friend over to help and as soon as the engine is cranked over the fuel injectors and constantly dumping fuel. In addition to changing out the O2 sensor, i have also changed out, spark plugs, wires, distributor cap and rotor, idle air control valve and ECM. I also did ohm checks/voltage checks on all other sensors and they checked good. Also ohms checked and voltage checked the injectors and they are good also. The other problem is after the truck is driven for about 10 mins it constantly dies and i cant move it more than 5 feet at a time. After the truck sits for a few hours it starts up fine, and will drive for about another ten minutes. This may just be a result of the engine flooding from too much gas from the injectors but im not sure. ANY help would be GREATLY appreciated!!!!

v/r
SSgt John Hinckley, USAF

 

If you are running that rich, you should be able to smell the exhaust being very strong. In fact it may even burn your eyes. Do you have a throttle position sensor on that motor?

 

Or it might be the opposite...not enough gas. Check your fuel pump and filter. It also sounds like a bad coolant sensor. I would double check it. It is the one next to the the thermostat. Did you make sure the ECM was compatible. It needs to have a 350 chip inside it.

 

RUFFNECK4LYFE- I do have a throttle position sensor. I did a voltage check on in per the Haynes repair manual, and it checked good, however im at a loss, so i bought one last night and will be putting it in tonight. I just changed out the plugs, and i took a few out to check them and they are already covered in carbon again...

Mr_Shamrock- I did an ohms check on the coolant sensor. i believe that before you turn the truck on it has high ohms, and as you start the truck and warm it up the ohms went down. It may be the other way around, however it was correct according to the Haynes manual. I double checked the ECM, and it matched the part number of the one i took out, so im hopeful that it is working correctly.

Thank you both so much for your inputs and anymore you have is greatly appreciated.