Low Fuel Pressure

[dougfuller]

Hey guys wondering who could help me out running at idle only has 30psi fuel pressure at idle, and only goes upto around 35psi engine off

Has walbro fuel pump running on full 12v from battery

new fuel filter

stock injectors

stock regulator

using a turbosmart fuel guage setup on the line from the filter to the back off the injector rail

R33 gtst rb25det

thanx any help would be great !

[89CAL]

The filter is in the return line isnt it? If its coming from the FPR on the rail to the filter then it is in the return line I'm pretty sure

[Nur33]

I think the filter would be on the intake side before the injectors, well thats where i put mine on both our cars, but just check that all the lines are on in the correct order it should go from the fuel pump to filter, then to fuel rail, out of the rail into the fuel regulator, then back to tank. Maybe this could be a problem if the fuel regulator is hooked up back to front.

[jiffo]

You need to check fuel rail pressure with the air/boost signal hose disconnected and blocked

Fuel rail pressure is around 2.5bar at zero manifold vacuum. That's about 37-40psi.

If you haven't removed the air/boost signal to the fuel reg, at idle it may be pulling around 20" vacuum or the equivalent of around 10psi.

So with the signal hose connected, you'd only see a fuel pressure of around 27-30 psi.

[89CAL]

for some reason I thought my car just came with the filter on the return side, but I dont remember lol. And I was lazy to go check

[Pal]

also could try and pinch the fuel return line and if rail pressure increases, then your fpr is stuffed. fuel filter is on the intake line. no good filtering fuel thats already gone through the system

[dougfuller]

I think the filter would be on the intake side before the injectors, well thats where i put mine on both our cars, but just check that all the lines are on in the correct order it should go from the fuel pump to filter, then to fuel rail, out of the rail into the fuel regulator, then back to tank. Maybe this could be a problem if the fuel regulator is hooked up back to front.

the incoming fuel is going through the filter into the rail then out the reg to the fuel damp back to the tank thats right isnt it?

[dougfuller]

You need to check fuel rail pressure with the air/boost signal hose disconnected and blocked

Fuel rail pressure is around 2.5bar at zero manifold vacuum. That's about 37-40psi.

If you haven't removed the air/boost signal to the fuel reg, at idle it may be pulling around 20" vacuum or the equivalent of around 10psi.

So with the signal hose connected, you'd only see a fuel pressure of around 27-30 psi.

disconnected the air hose to the reg and blocked the feed, it went from 29 to 35 psi.

[dougfuller]

also could try and pinch the fuel return line and if rail pressure increases, then your fpr is stuffed. fuel filter is on the intake line. no good filtering fuel thats already gone through the system

i pinched the return line from the reg and the fuel pressure was rising all the way upto 60 psi if i left it there does this mean my reg is gone?

[Pal]

looks like the fpr is passing

[jackrose01]

Low fuel pressure, it is difficult to run the country. If you are worried about the pressure on oil prices, the installation of a Mei Ling M55A is a pump with a high volume pump std spring. When all fails, do a fuel pressure, fuel quantity test, could save you from chasing your tail and throwing good money at the wrong problem.