Just installed Isspro Rail Pressure and Fuel Pressure gauges. Rail pressure seems to be good, roughly 7000 at idle, 15-17000 cruising and around 23000 WOT (not to sure ran out of road before I could get a great look) Fuel pressure is where I am having issues it seems. Idle pressure is around 7psi, but it never gets any higher. Normal accelerating is goes down to 3-4 and WOT it drops to 0psi, however, I notice no drop in rail pressure or anything when I am like that. I am running the 70hp tune on the Smarty Jr with the 50hp injectors and am wondering if the lift pump is going bad, or just not enough to keep up with what I have in my truck. Any ideas? It is the factory lift pump and both fuel filters were changed roughly 1500 miles ago. Gauge sender is located on a banjo snubber on CP3 pump.

 

My money is on the LP not being able to keep up.

 

I agree. The lift pump is weak. It should be producing 10psi at idle and at WOT it should not go to 0.

 

my fuel pressure is just above 10 at all times...no mods or tuners.


As long as you have any positive lift pump pressure readings you are fine........it's when it goes below zero that means you are not supplying enough "lift" to your injector pump