Fuel Pressure Oscillating?
07-07-2013, 06:31 PM
#1
Fuel Pressure Oscillating? Hi All,
Been doing some reading and most fuel pressure threads I find have to do with pumps not being adequate at higher power levels, etc.
My issue I can't seem to find anything about... So hoping someone can help me out
Basically the car hasn't moved much over the last 2 years, it's had maybe 300miles put on it. Over the last 2 years the motor has been freshened up and some body work done.
The fuel system is 42# lucas injectors, Walbro 255 and Hotwire kit, which have all been installed for 3 years. Fuel pressure was always a constant 64-65psi.
Fast forward to this year after sitting over the winter (nothing strange here same thing I've done for 10yrs). I fire up the car to work on the tune with the new motor and notice my fuel pressure is walking around 64..55...34..60..12..60...etc I thought it was the gauge but after carefully driving watching HPT I'm getting the slightest knock on throttle tip in when the pump pressure lags. Now it does this at idle and driving around, constant or varying MAP values.
I tried swapping Relays and checked fuses so far... But beyond that all connections seem fine. Hoping for guidance, but leaning towards a bad pump?
Thanks!
Been doing some reading and most fuel pressure threads I find have to do with pumps not being adequate at higher power levels, etc.
My issue I can't seem to find anything about... So hoping someone can help me out
Basically the car hasn't moved much over the last 2 years, it's had maybe 300miles put on it. Over the last 2 years the motor has been freshened up and some body work done.
The fuel system is 42# lucas injectors, Walbro 255 and Hotwire kit, which have all been installed for 3 years. Fuel pressure was always a constant 64-65psi.
Fast forward to this year after sitting over the winter (nothing strange here same thing I've done for 10yrs). I fire up the car to work on the tune with the new motor and notice my fuel pressure is walking around 64..55...34..60..12..60...etc I thought it was the gauge but after carefully driving watching HPT I'm getting the slightest knock on throttle tip in when the pump pressure lags. Now it does this at idle and driving around, constant or varying MAP values.
I tried swapping Relays and checked fuses so far... But beyond that all connections seem fine. Hoping for guidance, but leaning towards a bad pump?
Thanks!
07-08-2013, 04:55 PM
#2
9 Second Club
Check voltage supply to the pump, but as you've already figured, something is very wrong.
64-34 is a huge variation. It could be pump or regulator related, or power supply to the pump.
64-34 is a huge variation. It could be pump or regulator related, or power supply to the pump.