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Discussion Starter #1
when i first drive my car its fast as hell and slowly gets slower

on my fp gauge it will be at 40 when i ture the key on then still 40 when its running and after about 10 min of running it will be at like 35 then 30 then 25 and keep going down . key on engine off, key on engine running dosent matter

at first i though it was my 255lph pump that was about a year old but changed it last night and no difference

btw when its cold/nighttime it will take longer for the pressure to go down


so whats next ? regulator,relay ,wiring? no idea
 

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Discussion Starter #2
fuel filter is new btw, and no leaks
 

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Check Amperage to pump, ensure all connections are good. Make sure fuel lines and return don't have any restrictions.
 

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Discussion Starter #5
just changed regulator and no luck


it must be electrical/the relay

how would you test those
 

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what part of fuel pump did you not understand? Unless your battery is going dead as the pressure drops. But its probably the fuel pump.
 

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Discussion Starter #7
what part of fuel pump did you not understand? Unless your battery is going dead as the pressure drops. But its probably the fuel pump.
im on my second fuel pump already(it says in my first post)

i changed it like 3 days ago for an new one and the one before that was only like a year old
 

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I had a problem with the fuel pressure regulator. The diaphragm was found to be bad. The Engine would start and run fine, but would misfire and just not run right once power was applied.
An easy test to see if the Diaphragm is bad, is to connect a fuel pressure guage, start the engine, once the pressure is up, shut the engine off. The Presure should hold, if it falls right away, the diaphragm is bad.
 
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