I just replaced my PCM on my truck. Everything was going well until my dad took it out yesterday. When he started it up, the check engine light came on and stayed on for a while. He drove out the rode, the check engine light went off and all hell broke loose. He said that the truck was acting as if you were pumping the gas and at the same time the gas gauge started going from 3/4 to empty and back. This obviously set off the low fuel bell over and over. It also stalled on him 4 times. He said that it started fine though. Then the check engine light would flash on and off with the turn signal. It also flashed on and off at one point while driving down the road. At that time it seemed to start running better. Then the check engine light went off and it started doing it all again. I have looked at a few forums regarding the surge but I didn't see anything for all the problems at once. Didn't know if it was TSP or IAC related or did my PCM possibly go bad after a week. It is an aftermarket PCM with all the current updates. I also told him to remove the neg cable from the battery for about an hour to see if that would do anything. Any ideas??? Any info would be greatly appreciated!!! Take Care!!!

 

Should have checked to see what the code(s) are first. Before resetting the PCM. Have him take it to Advance , Autozone or where ever and they will check the codes for free. You can try the key method, but IIRC it will only work if the cel is currently on, it won't show you code history.

 

maybe the fuel system relay?. i've never heard of that happening before but that would be the first thing i'd check.

 

Sure does sound like some kind of power issue to the fuel pump or ground somewhere doesn't it.

 

Thanks. He is going to get it checked. He did reset it and it came back. I now that I said it went bad again after the check enging light stopped flickering on and off. That was wrong...he said that when it surged, the light would flicker on during the surges. He said that the gas gauge movement didn't happen this time. I think that may be a sending unit issue all it's own. Thanks again for the info!