99 7.3 loss of power

[puma]

Hi guys I have a 99 f350 with 220k. It started acting like its starving for fuel. in park it idles and revs up fine. when you drive it and pull any hill it blubbers like its running out of fuel. no dtc's of course new filters. Is this a symptom of the lift pump?Is there a pressue check for the lift pump?
Thank for listening

 

[Tail_Gunner]

On the back side of the fuel filter housing, there is a plug where you can hook up a pressure gauge to measure fuel pressure. But sometime fuel pressure at idle will be fine, but will fall off dramatically on the highway with a trailer in tow.

When my fuel pump went out, it would idle with 60 psi fuel pressure. But pulling a trailer up a hill, the pressure (and engine power) would drop off "a ton" down to about 10psi. I was able to diagnose the bad fuel pump when I installed an "in-cab" fuel pressure gauge.
View attachment 8542

 

[dpantazis]

pump is frame mounted under DS seat.

you might be sucking air from one of those st00pid fittings at the pump.

what is your fuel level? might be sucking air from the in tank mixer too.

 

[Tail_Gunner]

you might be sucking air from one of those st00pid fittings at the pump.

what is your fuel level? might be sucking air from the in tank mixer too.

Agreed.

If it runs better with say a 1/2 tank or more, and runs worse with 1/4 or less, that is a symptom of the POS mixer assembly sucking air inside the tank. The "Hutch mod" is the popular fix for fuel line, "air-sucking" issues.