Archived help, low fuel pressure

[Dallan]

about six months i installed a new injector pump and along with that i decided to install a holley blue push pump. it has ran awsome and i've been holding 27 psi at idle and never dropped below 12 when i hammer down. well now its idleing at about 13 and it drops to 0 when i hammer down. is the pushpump going or is it because of the low temperatures (5-10F). anything would be appreciated.

 

[bmoeller]

Given the ambient temp, I'd change the fuel filter first. Then post back if it doesn't solve the problem.

 

[Dallan]

but I just changed it about 5000 miles ago, is that too long. how often should i be changing it?

 

[DavidC]

Fuel filters are not really a time or mileage thing as bad fuel or contamintes can plug a filter shortly after changing it. Since you are showing low pressure the filter is the cheapest thing to change first. As long as the pressures stay reasonable I still change mine every 10k.



Dave

 

[Dallan]

ok, i replaced my fuel filter and it didnt make a difference. like i mentoned eariler, it is only 5-10 degrese here and at night i drops below 0. i am still lost as to what to do.

 

[DavidC]

I see two options. Hook your suction side to a 5 gallon jug of fuel and see if that clears your pressure problem (probably will have to purge lines). If it does solve it you have a suction side problem (probably screen in tank). If the pressure remains low it is most likely the pump. I would try not to suck the pressure below 5 in the meantime so you do not hurt the VP. Granted the fuel is probably thicker at your temps but the fuel should heat as you drive and the pressure should rise if the problem stemmed from low temps. Another thought is that you do not have full voltage at the pump which would lower your pressure.



Dave

 

[bmoeller]

but I just changed it about 5000 miles ago, is that too long. how often should i be changing it?

IIRC, the interval in the book is 15k miles, but I've had a filter (which is quite a bit bigger) on a big truck plug in less than one load of fuel. Even had a filter on a portable tank plug in less than 2 seconds.