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I have a 2007 VW Rabbit that has had starting issues. A few thousand miles back, it would not start, and I changed the plugs, ignition coils, fuel injectors, air filter, and fuel filter. It then started, but now, it has developed an issue where many times I have to turn the car over for 5+ seconds to get it to start. It tuns over great with a newer battery, so I don't expect it has to do with the starter. After it starts, it runs great, and restarting it soon after, usually yields a very quick start.

I brought it up with my mechanic, who couldn't diagnose it because it starts fine without sitting. He agreed with me that it was likely a fuel supply issue, and recommend K-44 cleaner. That did not seem to help.

I would think that it is the fuel pump, but if this is the issue, I would expect some problems while I am driving the car as well, but this does not seem to happen. Any thoughts on what to try next?

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  • Have you tried leaving the ignition switched on for 30 seconds before trying to start the engine?
    – HandyHowie
    Jul 4, 2022 at 5:31
  • @HandyHowie - What does this do? Doesn't VW pressurize the fuel system based when you open the driver door?
    – David
    Jul 5, 2022 at 16:24

2 Answers 2

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If there is no visual leaks or indications of a leak (ie fuel line connection, regulator) then it could be a faulty check valve in the fuel pump. Or the pump itself is not building pressure like it should. Does the car run well otherwise? Or does it have performance issues? Any other problems/noises/dash lights? I would try and get a fuel pressure gauge on the vehicle and start doing basic tests and watch if the pressure meets the specification.

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  • It runs great once it actually starts. No stuttering or other issues
    – David
    Jul 5, 2022 at 16:03
  • If check valve leaks, the pressure bleed down make take many hours. This means car won’t start after shutdown for the night. Easy fix is to live with it; turn key to on, count to four before turning key to start. Think of this as an anti-theft feature.
    – zipzit
    Jul 7, 2022 at 5:55
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Because the car runs fine after starting, and most everything else that could cause these problems have been completed, the most likely thing it could be is a faulty check valve in the fuel pump. Before you go ahead and just change the pump it should be diagnosed. This way you aren't throwing money at things that aren't the problem. To diagnose this issue a fuel pressure gauge is attached to the fuel rail. Then someone will turn the key to the on position (not start position). The fuel pressure reading on the gage should rapidly raise to the specified fuel pressure to this engine. It would generally be between 40 and 60 psi. Then have someone start the car. The pressure should drop a little bit. Then have someone turn the engine off. The fuel pressure should remain at the pressurized level or only dropping a couple of lbs. In about 15 minutes. If you have a faulty check valve the pressure will drop rather rapidly once the engine is switched off. If you do not use a fuel pressure gauge, another quick check is to wait long enough when you know it's going to struggle getting started, then turn the key to the run position (not start position) leave it there for 5 seconds then turn the key to the off position. Repeat this 2 more times. On the fourth time, start your engine. If it starts right up your check valve is probably faulty.

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  • That last step you have there of turning it on and off... Are you factoring in the fact that the fuel pump pressurizes when you open the driver side door, or is this doing something else besides pressurizing the line? I can hear the fuel pump run, but the only way to run it again right away that I've found, is to disconnect the batter and reattach it and then open the door again right away. Really curious if there is something else that turning it on and off does. Thanks!
    – David
    Jul 5, 2022 at 16:03
  • Turning the key to the on position turns the pump on for 2 to 3 seconds then it stops. Turning the key off and on again turns the pump on again for 2 to 3 seconds. Everytime you do this it is pressurizing the system. If it starts right up after doing this 3 or 4 times it means you successfully pressurized the system. If you go to the car without pressurizing the system it will have a hard time starting because the system lost it's pressure due to a pump check valve or leaking injector. He changed injectors so it's probably check valve.
    – Jupiter
    Jul 5, 2022 at 16:28
  • Reread your comment. If this car doesn't let you cycle the fuel pump then you need to hook a fuel pressure gage and see if the pressure drops rapidly.
    – Jupiter
    Jul 5, 2022 at 17:33

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