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[The Cambelt Kid]

Hi Peeps,

Not too sure if anyone on OOF knows much about the fuel pump in an Omeaga, but i think mine has thrown it's cards in as it’s not building up enough pressure...  I stared another thread about this a while back (http://www.omegaowners.com/forum/YaBB.pl?num=1221508779/27#27) and i thought the problem had faded away, well until my fuel gauge read less that 80 miles and then the starting issue returned.  Maybe it’s having a hard time pumping the dirty fuel from the bottom of the tank?

I managed to get around this so far by shorting the fuel pump relay out so as to give the pump all the current from the battery before starting her, this seemed to work every time which was reinforcing Kev’s theory that the pump was starting to fail.  But now this trick fails to work, no matter how many times i start the pump before cranking the car wont start.  I think the pump is failing to get the petrol in the fuel rail up to 3 bar.

I tried to take the fuel pump cover off today to check the pump but the dam thing wont shift.    I tried whacking the plastic ridges with a piece of wood and a mallet and it refused to shift.

I think i may cut my losses and but a new pump from the stealers tomorrow and replace in the evening, no matter how tight the pump cover is, I’ll have to get it removed!

Does anyone have any thoughts on the GM fuel pump, do they fail in such a way?  Do they just die and fail to pump or do they loose their grunt and fail to pressurise the fuel rail

Any help on this would be much appreciated.

[The Cambelt Kid]

Incidentally, I took the fuel filter off today and switched the pump on and clean petrol was running freely.  I also took the fuel inlet pipe at the engine and pumped fuel into a pint glass and again this was running freely.  I also put a piece of hose pipe from the fuel return on the fuel rail and pumped into a pint glass, this did fill the glass but the fuel flow rate was much lower, not too sure if this was ok?

[Matchless]

Best to get the pressure measured at the fuel rail, if you had fuel coming out from the return pipe then it suggests that the pump may be OK. If you have starting problems then check that the fuel pressure comes up as you start cranking. (2.0 runs pump briefly at ignition on, V6 waits for cranking signal)

What symptoms do you have?
Lots of cranking before firing up could be a faulty crank sensor, pump wont run until ecu confirms cranking from the sensor.
If you have a leaking injector starting can be difficult. Try opening the throttle during cranking, if it fires up easily then it suggests fule leaking into manifold when engine is off.
Ok at idle but dies under load is often a blocked fuel filter.

[Matchless]

Just read your other posts, confirm you have fuel pressure before blaming the pump.

De-pressurise the fuel rail at the schrader valve or by loosening the feed union.
Crank, and if no-start, see if there is any pressure in the fuel rail. Need a gauge really but if there is pressure then the pump must have run.
If no pressure then swap the fuel pump relays.
If there is pressure then try eliminating the lpg wiring...the connections to the petrol injectors will have been cut and run through the lpg controller.

[The Cambelt Kid]

Hi Matchless,

I loosened the feed union and fuel quite a bit of fuel dribbled out.  I also put a bit of hose from the return union and ran the fuel pump and fuel was pumped into a fuel can, although not as much as was going in.

The thing that has me confused is that for the past 10 or so failed start i can run the fuel pump manually (by shorting the relay out) and the car starts. It points to a pump that's not building up the pressure.

Is it worth replacing the crank sensor as a matter of standard procedure?

Vauxhall fuel pump on TC is £126.90 and megaVaux charge £47.  so a fuel pump might be an expensive 'educated' guess?

Cheers
Marc

[Matchless]

Are you shorting out the relay contacts (big tags) or grounding the relay coil?

If shorting the contacts then it could be that the relay is faulty

[Kevin Wood]

If shorting the contacts then it could be that the relay is faulty

I agree. Return flow indicates it's up to pressure and if the fuel pump was weak I'd expect fuel starvation under heavy loads.

Can't explain why it depends on tank level. Maybe the relay contacts have gone high impedance and can't supply enough current to start the pump under cranking. (do the pins get hot after running for a while?)

How many volts are you getting across the pump when it's running?

Kevin

[The Cambelt Kid]

im just going to check the voltage and report back.