Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: terry paget on 09 December 2015, 10:31:18

Title: 2.5 lazy starter
Post by: terry paget on 09 December 2015, 10:31:18

2000 MFL 2.5 petrol manual estate
This is not the car that has just gained a new clutch and slave cylinder, this is the car I retrieved from Jonny when I returned his 2.2 to him with new head gasket.
It always starts, but requires a 5 second engine spin before it does so, unlike all my other Omegas, which fire up in the first second or so. I suspect a fuel pressure problem. Where should I look?

Title: Re: 2.5 lazy starter
Post by: 05omegav6 on 09 December 2015, 10:43:18

Could try swapping either the pump or the pressure regulator... does it spin over readily enough? If not, then battery would be the obvious starting point :y

Title: Re: 2.5 lazy starter
Post by: Nick W on 09 December 2015, 10:58:13

Is it any better if you let the pump prime the system before cranking it over?

Title: Re: 2.5 lazy starter
Post by: Kevin Wood on 09 December 2015, 11:01:27

Any codes in the ECU? Might be the start of a crank sensor issue?

Title: Re: 2.5 lazy starter
Post by: terry paget on 09 December 2015, 15:20:25

I don't think it's battery, it spins with great vigour. Crank sensor never occured to me, but it's never missed a beat while running.
After a 4 hour stand loosening the 19mm fuel feed nut connector does not result in a fuel spray, so the fuel line is no longer pressurised. On other cars I find it is. I don't know how to prime it, Nick, I have tried turning on the ignition without starting the engine, but this does not pressurise the line.
My impression is that normally fuel lines remain pressurised for days, but on this car it does not. So pressure is leaking away, either through the pressure relief valve or back down the feed line into the tank. Can it leak back past the pump? Is there a valve there? I thought the pump was centrifugal. If so when stationary fuel could leak past it. I imagine a leak in the line would give itself away by smell.
I thought the fuel pump only ran when ignition was turned on, crank sensor detected 500rpm or above, or starter was turning. Is this right?
Sounds like leaky pump to me. Are all estate pumps the same? Could it be pressure relief valve?

Title: Re: 2.5 lazy starter
Post by: 05omegav6 on 09 December 2015, 15:27:23

All Omega petrol pumps are the same... The difference is the regulator on the fuel rail :y

Title: Re: 2.5 lazy starter
Post by: terry paget on 09 December 2015, 20:51:59

Quote from: Harris K Telemacher on 09 December 2015, 15:27:23

All Omega petrol pumps are the same... The difference is the regulator on the fuel rail :y

Thanks. I presume different models have different fuel rail pressures. Is it marked on the valves, or I need to find a valve from a similar car? I must have some from 2.5 petrol engines in my parts heap.

Title: Re: 2.5 lazy starter
Post by: 05omegav6 on 09 December 2015, 21:28:52

3 Bar from memory :y