Kiss_My_99SS

iTrader: (8)

I'm running the mp-4301 pump with external regulator installed.... Shouldn't this pump hold some fuel pressure when turned off..... The pressure dumps right off when pump is turned off.... Also pump is always loud like it never primes... Just running wide open at all times.....I've tried pinching off the return line and pressure jumps up as its supposed to and pump quiets some but just doesnt seem right..... Any ideas? Thanx.....P.S. I've got the regulator set to 55 psi and when I pinch off the return pressure jumps to 90.

NicD

iTrader: (7)

It won't hold pressure since there is no check valve and the pump is fairly loud.

bgblockelcamino

iTrader: (9)

yeah there is no check valve in those pumps. although it primes very quickly when you turn the key. they are typically loud

davidws6

iTrader: (36)

I'm in the same situation. I stuffed the 4302 on my TA and mine sometimes takes 2 or 3 key on/off's to prime up the pump. If not, crank, crank......
Though it sure keeps the press rock solid once it starts running.