I had my fuel pump go out here while back and I installed a new pump and now when i go down the road it starts popping and sputtering and the random misfire code comes on. It gets so bad at times i look at my fuel gauge and its showing empty and the truck will barley run i have to turn the truck off and turn the key back on untill i hear the pump kick back in. Then it is fine for a little bit then it will do the same thing I do have a boost pump but i would not think it would cause all of this? But I guess i just need your oppinions as to if it is the fuel pump still. Thanks Allan

 

b u m p

 

Can you put a fuel pressure gauge on it?

 

I've heard of people splitting the main plastic/rubber line at the pump (inside the tank) causing exactly as you describe.

 

Did you replace the fuel filter at the same time? How about the fuel pressure regulator? If all else fails see if the Intake gaskets are leaking. That can also cause a random missfire code and is common on 2002 up Flex fuel models. GM has a TSB on it. The fuel pudles up around the gasket and it ends up causing a leak. If that turns out to be your problem, check the intake ports for flatness. They recomend replacing if its not square across 2 ports or something like that. I just sanded them down till they were alot closer. I wish I had the TSB for this but I don't. Hope this helps,

 

A guys truck around here had that problem.. put a Fuel Pressure gauge on it and it was really low.. His new FP was only 1 week old. Got a Walbro 255 and its good to go now.. Hope you get it figured out..

Where you from in MS?

 

I have replaced the fuel pressure after changing the pump, and also cleaned the fuel rails changed the fuel regulator and it still had this problem. The reason I had a fuel problem in the first place was it looked like someone had poured awhole lot of really dirty water or just really bad gas with alot of water in my tank and it killed the pump. As soon as i had replaced the pump it started the spitting and popping noise at times i can be driving and all of a sudden it will die and say i have no gas and will not start i turn the key on and off to hear the pump and its not even coming on i can wait a few minutes and it will kick in and you can drive again. Thanks for the help guys

 

I am assuming you flushed the tank when you swapped in the new pump and then put new fresh gas in?

 

Here is what it should look like at Idle and then at idle with the vacum gauge pulled off.

 

If your fuel gauge is acting up too my guess would be a wiring problem somewhere.