GMC Repair: Truck Stalling problem, gmc sierra, doc moore

Question
Hello,
I have a 87 GMC Sierra with roughly 90000 miles. Anyway, it is having some stalling problems. This is how it happens. When I am giving little or no gas and then push on the gas pedal, it will act like it is getting no or possibly too much gas and trys to shutdown. It doesn't do  this at speeds above 30 or so. I have added gas treatment, oil treatment, water remover etc.. But nothing seems to work. Could be the fuel pump I guess, but since it is just an older work truck, I would like to try an easier and cheaper fix first. Do you have any ideas? Thanks so much for your time and I value your opinion.

"Doc" Moore  

Answer
There are a couple possibilities that are quite common to fail intermittently WITHOUT turning on the CHECK ENGINE light on the dash, They are:

(1) The TPS sensor (Throttle Positioning sensor) This sensor can be manually tested using the proper sequence using a quality digital multi-meter.

(2) You could, If you suspect that it is the in-tank fuel pump that is causing your problem to cut the fuel line along the frame rail and mount an external fuel pump making sure you use the correct PSI pump for the fuel system and just leave the old pump in the tank where it is as it will not cause any problems as fuel will still flow thru it.

(3) Are you experiencing ANY transmission problems such as erratic and or no OVERDRIVE engagement at times and or engine stalling out after you have been driving the vehicle for 30 or so minutes of speeds above 50 MPH ?.


Let me know,

autohelp (NM)