I have an inline fuel pump to boost fuel pressure. This just started. When I stop and fill the truck or just shut the truck off for like 5mil and start it back up the pump will get real loud and the pump will come on and off for some time. Thought it was a bad pump but put a new one on and it still dose it. Got any ideals??

Little more info may help. The pump is an inline Walbro pump. It only dose this when the truck has been shut off for a short time like at a fill up or run into a shop and back out. It you leave it off for like 30 minutes it will be fine. When you turn the truck on you can hear the pump is a lot louder and it will go on and off for around 3-4 minutes or so then clear up. The pump will say off just lone enough to kill the motor then back on.

 

Is the additional punp running off a Hobbs switch? Or some other type of activation?

 

What year is the truck?
Get a test light or a simple light inside the truck hocked up to the pumps wires. If the light is on when this happens its either the boosta pump, the pump inside the tank, or a ground issue with the boosta pump.

The pump in the tank stops or has issue will cause a cavitation in the line.

 

I've seen this happen when the in-tank pump dies. Disable the inline pump, and pressure test the in-tank pump by itself. I'd bet that's your problem.

 

Did the light it goes off

 

Will try this next. Have a new pressure regulator was thinking it was that but have not tried it. The Truck is an 02 with a 5.3

 

If light us going off that's electrical.
Follow ur hot wire back to it's connection point.
Corrotion at a splice is common.
Also make sure that wire is not kink'd.
Wire can break internally.

 

I hooked the pump start to the battery with a switch and the pump runs fine no on off. Checked all the ends of the wires and all checked out fine. Been down a few days hope to be back at it next week.