fuel pressure drops

06f250powerstroke · Jun 16, 2012

I have my fuel pressure set to 65psi and it never moves at 3/4 throttle but at WOT it will drop to 52 psi. Im running a FASS 95 and a RR kit, could this just be my pump not being big enough?

strokin6L · Jun 16, 2012

is that a low pressure pump or a stand a lone high pressure pump

06f250powerstroke · Jun 17, 2012

not 100% sure i took my factory pump off so would that mean its a stand alone?

windrunner408 · Jun 17, 2012

Yes it is a high pressure unit. I am inclined to think your pump is just not big enough but it's not bad as 52psi is just fine for your injectors. Do you have a sump?? I would try one of those if you dont. It may help remove some strain on the pump.

I have a sump with an AD150, feeding the stock pump, feeding a RR kit and my pressure drops from 64psi at idle to 50-52psi at WOT.

faster6.0 · Jun 17, 2012

Turn the regulator on the RR down to 55 psi and see if it helps.

strokin6L · Jun 17, 2012

i installed a stand a lone FASS on my buddy's '05...think it was a 95/90 series pump. he's running stock injectors with no RR and fuel constantly stays at 62psi and never drops.

Strictly Diesel · Jun 17, 2012

Locate the return hose on the FASS (one going back to the fill neck) and clamp it shut (with something that won't damage it like hose clamp pliers). Drive the truck and see if it's any different. If it still drops pressure, the pump isn't moving enough volume. If it holds pressure with the return hose clamped shut, the spring and ball combo in the pump isn't strong enough. I know that FASS is recommending the use of an external fuel pressure regulator (one of theirs naturally) for higher pressure applications, both because it's adjustable and also because the pressure can be dialed up higher than their spring/ball combos.