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Is my fuel pump on its way out?

1017 Views 3 Replies 3 Participants Last post by  sandnut
I've got a regulated return system with the fuel pressure gauge mounted in the dash. The pressure is set at 66 #'s, and normally, under heavy acceleration, it drops to 60-62 #'s. Yesterday I noticed that it would quickly spike to around 74, then drop down into the low 50's. I tested it a little more by doing some longer than usual hard acceleration runs (floored from 0ish-85ish on freeway entrance ramps) & saw that the pressure would drop down into the low 20's.
It seems to me that with a healthy pump, a 4-5 psi drop would be normal, but a 40+ psi drop is a bad thing, right? I didn't notice any loss of power, & in normal driving, the pressure never really moved. Do I need to look into replacing the pump (it has 117k miles on it)? If so, is my best bet with an OE pump or is there a better (read: just as reliable but less money) aftermarket option? Would a lift pump like FASS or AirDog system fix the problem, or would that only be a 'band-aid' fix?
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My pump has 78K miles on it and it is going strong. For 70K miles it has not had to sip fuel through a fine straw. I have 3/8" id. SAE 30R7 fuel hose running from a reamed fuel pickup to the 2 micron Dahl filter and 3/8" hose running from the Dahl filter to the pump. None of the lines have a sharp or tight radius bend. The restriction from this system is VERY low, on the order of a several inches of water. The pump can meet the demand of my EHed nozzle DDP AC single shot injectors at WOT with less than 2 psi drop in fuel pressure. If you opened up the supply side to the fuel pump it would probably have less trouble keeping up with demand.

I can record the maximum fuel pressure seen by my SPA technique gauges and have seen spikes as high as 90 psi. No problems in the past 20+K miles with this behavior. My pump holds 70-72 psi. without issue. I am not sure I would worry about a transient spike in pressure. I agree with the comment about changing the filter. Any restriction can impede the output of the pump to the injectors.
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