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Old 11-14-2019, 12:41 AM   #1
livingez123
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Default 2.0TSI no start sometimes

Ok, I'm not a newbie when it comes to VW's and I have owned way to many to count but my current car is a 09 with the tsi. It runs perfect, smooth, not a blip anywhere. The issue is that after I drive it and turn it off and go to start it again it will run and then die. Try to start it and it just turns over and tries to fire off but just stumbles and dies. It is fuel related because it will fire off and run on starting fluid. I can put my hand on the top of the fuel pump module and feel the pump run and turn off. I have no codes of any kind come up when this happens. I did have a low rail pressure code several weeks ago but I watch the pressure on my vcds and it looks good. I wonder if it could be the low pressure fuel pump in the tank failing or maybe the fuel pump module. The car has 96k on it. It will start after about 15min of sitting but it is getting harder to start when this happens. Any thoughts on this are appreciated.
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Old 11-14-2019, 05:55 AM   #2
doregan
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This may be a stretch, but, if it has one, the fuel pump relay circuit board may have a crack in it causing intermittent starting. Had this problem on an Audi many years ago and no one could diagnose what was causing the problem.

Good luck.
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Old 11-14-2019, 12:29 PM   #3
voxmagna
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The problem with this kind of intermittent fault is doing tests whilst the fault is there. From memory the low pressure fuel pump isn't that hard to remove for checks. Most pumps have a fine mesh filter sock on the end so it's worth checking that (and the tank) is clean of any gunge. The other issue might be air getting into the fuel lines, which doesn't always show as low pressure, but it certainly stops starting.

You have to be very careful and take precautions but when the fault is present I think I would try lifting a fuel injector to see if there's a fuel spray pattern whilst cranking?

MY07 EOS is diesel but I think on both the low pressure pump and control unit are easy to get to under the seat.

One obscure fault can be related to the fuel tank venting system which is more complex for USA models. If the charcoal filter is blocked and the fuel tank isn't venting correctly, the fuel pump builds up a vacuum in the tank which eventually starves the pump of fuel. You can check by removing the gas tank cap. If there's a whoosh of air rushing down the filler, the tank isn't venting.
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Old 11-17-2019, 02:28 AM   #4
livingez123
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More info, it does it after 2 or 3 quick stops. I will drive the car about 15 miles stop, come back 5min later and start it again, drive for a mile and stop again for 5min start it again and it will idle for a min and then stumbles and dies. Yesterday when it did this I replaced the fuel pump control module and it still didn't start. I pulled the rubber low pressure line from the hard line on the intake and got about 100psi of fuel mist, not a stream of fuel. Turned the key to cycle the pump and got a bunch of air and then a stream of fuel. Connect the line back up and it started and idled perfect. Today the same routine, start...make a few stops and then it died again. Pulled the fuel line got more air and fuel mist, cycled the key got fuel and connect the line and it started and ran fine. Now if this was a 60's car I would say vapor lock, but this is injected with a return line at the filter so with that in mind I have to look at the filter and in-tank pump. Tomorrow I'm going to put a spare pump in the tank and see if I can get it to repeat the issue. If all is good after that I will order a new pump. If not then I will try a new filter but I just can't see it being the filter...I have been wrong before but not very often.
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Old 11-17-2019, 07:29 PM   #5
voxmagna
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I had a similar fuel pump problem on a motorcyce efi fuel pump. The fuel pump runs continuously from switch on. If there is air in the fuel line, the pump is trying to push fuel against air and in my case the pump would 'cavitate'. This is like boat props when the pump loses grip on the fluid, spins at higher speed with no pressure and doesn't regain grip until you stop the pump and restart. This only happened after I had broken and reconnected the fuel line. Since I knew there was no leak, it had to be caused by not removing air from the fuel lines before putting power on the pump.

I fiddled around with this and eventually decided to replace the pump. If your fuel line is not delivering a continous flow of high pressure fuel with no air in it, the air must be getting in somewhere or you have the same problem that the pump is cavitating in fuel. I don't see this as a controller problem? You should be able to remove a fuel pump to carefully check it's pickup strainer and test it in a bucket of keroscene (or water?) with a battery (no controller) , but thoroughly dry it afterwards and push some fuel through after testing.

Another possibility is there's a return flap valve in the pump which is faulty. Once the fuel pump is primed to recirculate fuel with no air, it should never fall back from the flow line into the tank. If fuel does this you can get a pocket of air in the base of the pump which starts the 'cavitation' and no output pressure. If you remove the fuel pump you should be able to attach 3 foot of hose, pour fuel down it until it fills level and it should not leak out of the bottom (inlet) side of the pump.

Your problem definitely now seems related to the fuel pump which I would remove, inspect, check and test out of the tank.
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Old 11-21-2019, 12:12 AM   #6
livingez123
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I replaced the intank pump with another one I had from a parts car and so far so good.I have done several short drives and stop and starts with no problems. I also replaced the filter at the same time...I know I should have waited on the filter to see if the pump by itself fixed the problem but I was leaning towards the intake pump as the main issue. I will know more in a few days with more driving.
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Old 11-26-2019, 08:42 AM   #7
livingez123
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Well it's still running perfectly. I have a new intank pump coming next week so I can swap out the used pump that I put in.
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Old 11-26-2019, 10:26 AM   #8
voxmagna
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Quote:
Your problem definitely now seems related to the fuel pump which I would remove, inspect, check and test out of the tank.
Glad the analysis worked for you.
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Old 11-28-2019, 12:42 AM   #9
livingez123
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Not going to waste my time testing and inspecting the pump, it's already in the garbage!
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