My truck recently started acting up. I put a new lift pump on it about 3 months ago. The truck will start, but right after it starts it starts to misfire if I push on the pedal it still misfires. Could it be the Ecm? Or the Vp44?

 

sounds like a mitsubishi

 

Misfire? Injector out....

 

It may fuel starved, a clogged filter or bad lift pump will do that. The OEM fuel lines are not the greatest and have a tendency to get pin holed. The OEM setup is a mix of steel tubing and semi-rigid plastic tubing. The steel can rust and rot out over time, and the plastic tubing gets brittle and cracks. These fuel systems need 100% liquid fuel in the lines, no air.

I've had both issues on my truck. I've had the lift pump stop running due to a bad electrical connection which fuel starved the engine at anything above idle (fuel pressure was 0). Sputtered a lot and was sluggish.

I recently had a air leak on the suction side of my lift pump which made the engine start missing and sputtering going down the highway (fuel pressure low, around 5 PSI). Didn't idle well and acted erratically, would have power at times, and then start sputtering the next. Would not restart after shutdown. My lift pump pre-filter got loose and was sucking air. Once I found that, and reprimed my fuel lines, it came back to life. That one worried me that the VP44 went out, but the low fuel pressure clued me in towards a fuel delivery issue.

Go over your fuel lines from tank to pumps carefully. Especially if you ever smell diesel fuel near your truck, good indication of a leaky fuel line. I replaced both lines (supply and return) on mine with rubber fuel lines from the tank to the engine.


ECM's generally are good or bad, not often they give weird issues.