fuel pump non return valve??

[Gabbo]

ive put a 2.0 8v in my nova 1.2 SPI. got the engine in and running fine. used a MPI fuel pump from a mk3 astra which i was told by you guys. when i turn the engine off the fuel pressure seems to drop. i have checked its not getting past the pressure relife valve on the rail and it doesnt seem to be. can it be getting back through the pump or have i done some thing wrong?
do these have a non return valve on the pumps if not what have you guys done to keep the fuel pressure in the rail?
hope that makes sense
cheers :)

[big gra]

i put a 2.0 8v in my nova a few months back, what a waste of time, didnt realize it was so much work, could hav epuut a red top in, same shafts and mounts needed. i used a mpi mk3 astra gsi pump and worked fine, probably dosent help you at all but oh well, haah im drunk, just got in from the pub :)

[Clean 2.0 nova]

I agree with Big Gra - His reply probably doesn't help.

[Lee]

What problem is this causing??????

[Adam]

Of course the fuel pressure will drop, the pump has stopped pumping......

[Gabbo]

yeah but surely its ment to keep fuel in the rail so when i come to my car in a morning etc it just takes a turn of the key to start. at the min i need to leave ignition on for 20 - 30 secs to prime the rail and fuel line.

i know tell me bout it i got the engine cheap so thought it would be an easy project but its more than i thought. all in now though just this fuel prob thats puzzeling me.

cheers :)

[Clean 2.0 nova]

The priming of the rail should be more or less instant from when you hear the pump starting. Don't think it anything to do with keeping the rail pressurized when the ignition is off. You have a pump feeding the rail, then an overpressure valve at the end of the rail that feeds back to the tank thus keeping the rail at 2.5bar or whatever pressure it is. You may have a knackered pump (air lock?) or pressure regulator, or a blocked pipe feeding the rail or even on the suction bit to the pump.

[Gabbo]

ive got it starting on the key now. checked the regulator at the end of the rail and its holding the fuel so ive put a non return valve before the fuel filter so this keeps the fuel up the line and in the rail and it starts great now.
thanx any ways guys :)

[Adam]

yeah but surely its ment to keep fuel in the rail so when i come to my car in a morning etc it just takes a turn of the key to start. at the min i need to leave ignition on for 20 - 30 secs to prime the rail and fuel line.

Turning the ign on for 30secs wont do anything.
When the ecu primes the system it does it for around 2secs max.

Most systems dont prime at all and they still start first turn of the key :thumb: