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Discussion Starter #1
what should the fuel pressure on a stock 12v lift pump? im measuring at the outlet of the fuel filter, its 6psi at idle andaround 30psi at crusing speed(dont have tach working yet lol) but at wot it dropes to around 18-20

i was thinking it should of been around 50 or so at wot, could i hook up my old holley pump off my 24v with a bypass regulator witht he mechanical pump. it will eventualy get a fass/air dog but funds wont allow right now lol
 

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Your pressure is low so you probably need a new overflow valve. Test by clamping the hose in the return line with some vice grips or something like that. If pressure goes way up then you need a new OF. 50 PSI is pretty high. 45 is about as high as you want it to go. Anything in the 30s is OK. Dropping below 20 on the road is not OK.
 

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Discussion Starter #3
could i use a pressure regulator?
 

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Discussion Starter #4
ok i checked it again

idle is 6psi, 1500-2000rmp(ish) is 18psi and crusing 70 and romping on it, it dropes to around 12-14


i pinched it off with vice grips the engine idled up a little and raised the pressure to 30psi
 

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Factory spec is ~20-25 psi fuel pressure at idle and ~30 psi at 2000 rpm (I say about because I don't have the FSM in front of me to give you exact numbers).

It sounds like your pressure is low if you ask me.
 

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Discussion Starter #6
i forgot to mention thats on my 97......the lift pump is fairly new. i have an adjustable regulator on my 98(running a 13mm pump) but it came with the pump....
 
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