Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: terry paget on 05 February 2017, 09:18:52
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2.5 petrol manual estate
I have mentioned this before. Unlike my other Omegas, this car does not start well first start of the day. First 2 second starter squirt, nothing, second squirt it fires up. Restarts it fires up first time.
I thought it might be lost fuel pressure at the engine, so first thing this morning I removed the fuel pipes at the manifold. As I suspected, no fuel spurted out. Pressure loss at the pump end? A leaky injector?
I replaced the fuel pipes and started the engine. It immediately fired up. That puzzled me too.
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Unlikely to be a leaky injector.
Mine does this occasionally, especially when the fuel level is low and it's been standing for a couple of days. I suspect the pump is a bit weak, but don't intend to change it until the problem is consistent.
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Pressure regulator might be failing... it's on the fuel fail between the injectors and the return line. Cheap enough new :y
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Silly question but doesn't the fuel system prime itself for a couple of secs when you turn ign on ?.mine does or at least makes a sound like it does !
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Silly question but doesn't the fuel system prime itself for a couple of secs when you turn ign on ?.mine does or at least makes a sound like it does !
No. On the v6 i believe the fuel pump wont run unless it gets a signal from the crank sensor. So the engine have to be turning before the pump starts. The four cylinder engines run the pump on ignition to prime however. Always figured that was why my girlfriends 2,0 fires immidiately when turning the key, while my 3,0 requires a couple seconds of cranking:)
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my v6 has always fired on first turn (touch wood) however in the weeks before the crank sensor failed it would occasionally miss an instant start, still starting fine but just a very slight but noticeable delay. could it be your crank sensor is on the way out?
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my v6 has always fired on first turn (touch wood) however in the weeks before the crank sensor failed it would occasionally miss an instant start, still starting fine but just a very slight but noticeable delay. could it be your crank sensor is on the way out?
I hadn't thought of that. Crank sensors are expensive, and troublesome on 2.5s. It would not explain why there was no fuel pressuire in the line yesterday morning, so I will change the pressure regulator first. Thanks for the thought.
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Weeping injector is the usual suspect and have seen it a few times.
Usually, if you floor the throttle and spin the engine for a few turns its enough to re-pressurise the injector rail and flush the neat fuel out the engine.
Then second go it starts instantly
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Pressure regulator might be failing... it's on the fuel fail between the injectors and the return line. Cheap enough new :y
This fellow. I have a couple of 2.5 lower inlet manifolds in my spares heap. I could swop the whole thing, but that's quite a job. |Haynes says I should change the O rings, but amazingly these look pretty good. I am tempted just to change the valve.
(https://www.dropbox.com/s/iew81a40bkzjlyu/FUELpressREGULATOR.jpg?dl=1)
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I would be measuring the fuel pressure before just swapping parts for the sake of it. Vauxhall even provided a test port to make it easy.
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I would be measuring the fuel pressure before just swapping parts for the sake of it. Vauxhall even provided a test port to make it easy.
It says 3.0 bar on the valve, so I know the relief pressure. I presume you mean the pressure relief valve by a test port. I suppose if I press a tyre pressure gauge on the test port it should read 45psi or 3 bar. Is that what you had in mind? I have a PCL Mk3 tyre inflator which came with a calibration, though TB does not have too much faith is the calibration.
Or are you suggesting that I should test the fuel line pressure whie engine is running, then immediately after engine stopping, then the following morning? That sounds instructive. I could do similarly on a different Omega. It might confirm what having no fuel spurt out in the morning suggested.
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my v6 has always fired on first turn (touch wood) however in the weeks before the crank sensor failed it would occasionally miss an instant start, still starting fine but just a very slight but noticeable delay. could it be your crank sensor is on the way out?
I hadn't thought of that. Crank sensors are expensive, and troublesome on 2.5s. It would not explain why there was no fuel pressuire in the line yesterday morning, so I will change the pressure regulator first. Thanks for the thought.
you should always carry a spare crank sensor, a cheap get-me-home one will do. Easy to fit especially if it has been done before (the cable will have been re-routed). It might explain the zero pressure assuming MonzaGSE is correct.
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my v6 has always fired on first turn (touch wood) however in the weeks before the crank sensor failed it would occasionally miss an instant start, still starting fine but just a very slight but noticeable delay. could it be your crank sensor is on the way out?
I hadn't thought of that. Crank sensors are expensive, and troublesome on 2.5s. It would not explain why there was no fuel pressuire in the line yesterday morning, so I will change the pressure regulator first. Thanks for the thought.
you should always carry a spare crank sensor, a cheap get-me-home one will do. Easy to fit especially if it has been done before (the cable will have been re-routed). It might explain the zero pressure assuming MonzaGSE is correct.
Not so easy to change, as discussed before, though one slim OOFercan do it with the car on level ground.
I discovered this morning that access to the ptessure relief valve involves removing the plenum. Having done that changing the lower inlet manifold is easier. Hmmm.
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More data. Twice yesterday car started on second squirt, but promptly stopped again. Ir ran normally on third squirt. I still suspect fuel feed problems for above reasons, fuel pressure control valve, or fuel pump. Crank sensor was changed in March 2013, 30000 miles ago. Any thoughts, chaps?
This job is temporarily on hold while I change heater fan on V828.
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The pressure regulator is just a spring in a can.
The pump is an electric motor combined with a gizmo, and it has run all the time the engine has for the last ?? years.
With that in mind, which is more likely to present intermittent faults?
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Was hoping to hear that you had sorted it, only ever had crank sensor problems with the 2.2 , very frustrating hope you get this sorted.
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Crank sensor was changed in March 2013, 30000 miles ago.
easy to fit another then, it will have been re-routed.
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The pressure regulator is just a spring in a can.
The pump is an electric motor combined with a gizmo, and it has run all the time the engine has for the last ?? years.
With that in mind, which is more likely to present intermittent faults?
Point taken. I thought |I had a spare saloon pump but not an estate pump. In fact I have two. The pumps look the same, but the fuel gauge senders have different float arms. I guess one is saloon and one estate. Are the pumps the same?
(https://www.dropbox.com/s/mlmazhuyu9cmx5v/FUELpumps.jpg?dl=1)
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Gentlemen, we have cracked it! My thanks to all for help. Here's how it ended.
Last Saturday I changed the fuel pump. I had a spare, in fact I had two, as saloon and estate pumps are the same, the only difference seems to be in the fuel gauge senders.
As soon as I had the boot floor plate off I guessed the trouble, for the hoses from the pump top plate were secured by Jubilee clips, not the usual special clips. Beneath the top plate the pressure hose from the pump was again secured by jubilee clips. Clearly the pump had been changed previously.
(https://www.dropbox.com/s/wjudo9amed0agq8/FUELpumpJUBILEES.jpg?dl=1)
My spare pump came with a special hose clip at the pump end, and I found one spare spring hose clip for the output pipe.
(https://www.dropbox.com/s/akeab9arwuohu8r/PUMPnewCLIPS.jpg?dl=1)
For the pipes to the engine I had to use jubilee clips, but I can easily change these if the fault recurs.