Bleeding Air from Fuel System
 

Had a problem today and fitted a replacement fuel pump.
The car now wont start, the pump primes and there is fuel entering the rails.
The car turns over and tries to fire, but no joy.

Had RAC out and with a manual primer installed just after filter under the bonnet the increased pressure it generated as chap squeezed it made the car fire up into life and run ok, but as soon as he let go of this manual primer it ran out of fuel and died again.

We think it could be:
1. Low fuel pressure if air getting into fuel system somewhere, highly unlikely though as tank is full and no pipes other than thoses on pump disturbed (and they were fitted correctly and clips refitted).
2. Air lock in fuel gantry/s and the valve isnt opening to allow return to tank, hance the fuel is not flowing through the rails (as more pressure than std fuel pressure is needed to push the trapped air out).

Does anyone know how to bleed trapped air from the fuel gantry/s?

Cheers,
Richard

you shouldnt need to bleed the system. Just turn the ignition on, let the pump prime, turn it off, turn it on again and let it prime, repeat a few times, and then try start the car.

Done a few pump swaps and its straight forward an simple.

If its not priming at all, i wonder if you have somehow managed to connect the pump up wrong? Re check the installation.

Agree totally with above :) never had a problem
Make sure the short pipe fom the pic up in the tank to pump is ok also the wires are the correct way round + / -

Agree with what has been said.. would hazard a guess that the two pipes on the top of the tank that are 8mm fuel lines are on the wrong way around.

Simon

The pump is priming, and fuel is pumping from the pipe that feeds the fuel rails from the regulator / filter under the bonnet.

This situation is the result of a flat battery we now think.

I used a booster to try and start the car, we think this spiked the ECU, which then caused fuse SBF-No5 under the bonnet to blow and stopped the fuel pump working.

Battery was disconnected, then reconnected, blown fuse replaced, fuel pump removed and bench tested (works OK).

The fuel system primes as normal, but when you remove the return pipe there is no fuel returning to the tank, only when the manual hand primer is squeezed does the car run as normal.

Thoughts now are that the ECU is dead and cant control the fuelling, or that the valve that allows a return to the tank is stuck closed and causing car to over fuel as under is own power coughs and splutters but wont fire up.

Sounds like you dont have the fuel pressure to open the fuel reg ?

Does anyone know what the fuel pressure entering the reg should be? 1995 WRX.

Cheers

Not sure on standard reg but a good starting point with fse/sx is around 3.0 bar at atmos

2.8 to 3bar is standard fuel pressure.

Sounds to me like you are pumping fuel at the wrong side of the fuel pressure reg and then the fuel is returning through the filter.. ie.. the pipes on the top of the tank are the wrong way around.

Simon

I'd go with that theory