So my truck kept stalling out and dying while driving. It will go about 5-10 miles and then stop running. The mechanic said it was the fuel pump so we replaced both pumps (single tank and in-line pump). Thought it fixed it but then it died again. They can't figure it out and now it runs rough while driving. Still haven't driven it very far because i don't want to mess it up.

I ran codes on it and need some help. KOEO codes came back with 87 (primary fuel pump circuit failure) so i replaced the fuel pump relay. Did nothing. I can hear the pump making noise when i turn the key. Help?

KOER test came back with 44 (Thermactor Air System Fault), 13 (RPM too low at idle), and 25 (Knock not sensed). My smog pump does not have the belt connected to it. Any ideas?

 

Does it start right back up when it stalls? If so, that might be related to the code 13. I would take the throttle body apart and clean around the butterflies and the idle air control motor passages.

Then get it going again and fully warmed up. While it's idling unplug the idle air control motor. When you do this the engine should barely run. If it dies right away, I would turn the idle stop screw in a little bit and and try it again. Get it so it barely runs with the idle control disconnected.

Then plug the IAC back in and let it settle itself. It might take a couple of starts and stops and driving down the road for the computer to relearn the new idle settings. See if that helps it.