i have an 06 2500 5.9L cummins that just got a new computer new injectors and a new injection pump. it will randomly just shut down at speed or just parked idlling am stumped. also related or not keeps throwing a p0148 fuel delivery malfunction code and derates the power. no code appears when it shuts down just when it derates power.need some help on what to do next. when it runs with no codes its perfectly fine. if anyone has had this problem i would love some help thanks.

 

You need to check the lift pump as may not be running all the time.

 

Definitely check for adequate fuel supply. That would lead me to think that's why it's shutting down at speed. If it was only upon deceleration or at idle I would think of a faulty FCA. Sure sounds like it's running out of fuel. Does it spit and sputter at speed before it shuts down?

 

no spit or sputter just a little shutter and thats it then its just like u shut the key off. any idea what the flow rate should be 4 the lift pump? and whats the best way to check? Is it just as simple as pulling the lines off at the filter and see what u get?

 

I would install a fuel pressure gauge and test the lift pump it could be a bad lift pump only working part time. had an 04 doing that and it was the LP cutting out now and then since the new pump it has not shut down on its own!

 

It sounds like the pump is running part time and the only way to check that is with a pressure gauge. You can check the flow by putting a container on the filter drain, open the drain valve then bump the starter, do not start. The pump should run about 25 seconds and you should get at least one quart of fuel, if much less then the pump is bad.