In a previous thread I started, my truck falls on its face at 3k rpms, even though I have a 4gsk. I replaced the overflow valve and replaced the pre-screen.

Today I hooked up a pressure guage and got the following results:

Idle 24psi.
No load @2000 rpm 24psi.
Under load (floored in 2nd) @ 3000 rpm 18psi.
When its under load and you lift on the throttle to shift, the pressure spikes at 30 psi for a second.

Am I correct in thinking the lift pump is bad? What should the fuel pressure be under load?

Thanks.

 

Under load, 32-35. You need to pinch off the return line hose and see if your pressure shoots up to around 60, if it does, your LP is good and it is probably the overflow valve.

If it doesn't, replace the LP.