Fuel pump priming

paulsv8manta · Post by **paulsv8manta** » Tue Sep 20, 2016 12:10 pm

Hi guys,
Just checking the system before the initial first start up, and found the fuel pump not working. Found out it was a faulty solenoid so new one in, but the pump is not priming when I open the air flow meter flap by hand I can hear the pump running. The ecu I've got is the 4cu not sure if this would have any influence.
Cheers paul

DaveEFI · Post by **DaveEFI** » Tue Sep 20, 2016 12:32 pm

If this is the flapper, the pump doesn't prime. It runs when the starter motor is running - and then via the flapper switch when the engine starts.

If you have the original pump and regulator in good condition and no leaks, the fuel rail retains pressure for a long long time. And gets up to full pressure very quickly.

Some after market regulators (and maybe pumps) don't have the same one way valves so take a lot longer to get up to pressure. Should make no difference to the running - but may do to how easily it starts.

ChrisJC · Post by **ChrisJC** » Tue Sep 20, 2016 6:25 pm

Can you measure fuel rail pressure? I used to put an oil pressure gauge on the cold-start injector pipe to make sure the fuel rail was up to pressure.

Chris.

Ian Anderson · Post by **Ian Anderson** » Tue Sep 20, 2016 6:56 pm

Positive and negative the wrong way around on the pump?

A HP pump tends not to suck so is ther fuel all the way through to the pipe where the Pump resides?

Ian

paulsv8manta · Post by **paulsv8manta** » Tue Sep 20, 2016 10:10 pm

Thanks Guys,
Dave, yes a flapper system that's a relief, starting to panic!
Might of made a boo boo though.
Existing fuel system pipework was 6 mm id for a straight 4 cylinder, I have upgraded it to 8 mm id thinking more cylinders more fuel. The existing electric pump is an external pump running 44 psi.
This maybe a problem in getting the system up to pressure.

I've installed an FSE Adjustable Fuel Injection Pressure Regulator with gauge as my second hand fuel rail didn't come with anything. at the moment its not reading any pressure although there is a petrol leak on the return hose on the FSE.

Cheers
Paul

DaveEFI · Post by **DaveEFI** » Wed Sep 21, 2016 8:59 am

Pressure is held between the pump and reg - so a leak on the return wouldn't effect this. The FSE I had wasn't good at holding pressure once the pump stopped. The fuel rail size wouldn't make a difference to the pressure, but would to how long it takes to come up to full pressure from zero.

unstable load · Post by **unstable load** » Thu Sep 22, 2016 2:10 am

Is it possible to wire the pump directly to a power source? If so, then find a point as far as possible away from the pump and open it to allow it to bleed, then power the pump up and let it prime the line.
Fuel systems are notoriously problematic if there is air in the system.

Once it's primed, it should then all be good when you crank, and the pump runs as DaveEFI said.

paulsv8manta · Post by **paulsv8manta** » Thu Sep 22, 2016 11:44 pm

All sorted, there was a blockage in the fse unit. God knows where it came from.
Now for the next problem!