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Old August 6th, 2007, 16:15   #1
fpruter
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Default Cold Start Problems

I have a 2000 VW Jetta TDI and it has problems starting in the mornings or after a long period of the engine not running. I have checked the glow plugs as well as the battery. The car will try to start and generally takes 30-60 seconds.

I've read somewhere online that if there is an air bubble in the fuel line it would cause that to happen. When looked under the hood I see a massive air bubble... a good inch to inch an a half long. Today, my friend noted that when the car finally started up the bubble was pushed through first.

Any suggestions on how to fix this problem or other possible solutions?

Thank you,
Francis

Last edited by fpruter; August 15th, 2007 at 09:08.
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Old August 6th, 2007, 18:10   #2
david_594
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A 1" air bubble isnt too out of line although your problem does sound like air is getting into your fuel system.

Take a look at your fuel pump and see if you can see any signs of leakage on the pump?
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Old August 6th, 2007, 23:57   #3
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That sounds to me like deposits on intake valves.You should have compresion checked.The glow plugs are only turned on only at temperatures below 5 degrees.Also it would not be bad to check injection timing.
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Old August 7th, 2007, 07:14   #4
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Check the fuel lines between your injectors and the return line. They are probably due to be replaced. If there is a leak fuel will siphon back into the tank. Could also be the fuel sending unit in your tank. I believe yours will have a check valve that is suppose to stop this from happening as well. Air intrusion can also happen with incorrectly installed orings on the T fitting on top of the fuel filter. If this problem surfaced soon after a filter replacement start there and just for giggles reach under the canister and ensure that the drain is tight.
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Old August 14th, 2007, 15:08   #5
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Quote:
Originally Posted by david_594
A 1" air bubble isnt too out of line although your problem does sound like air is getting into your fuel system.

Take a look at your fuel pump and see if you can see any signs of leakage on the pump?
From what I can tell I don't see any signs of leakage on the pump. Any other suggestions?
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Old August 14th, 2007, 15:32   #6
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Quote:
Originally Posted by Canadian_Grizzly
Check the fuel lines between your injectors and the return line. They are probably due to be replaced. If there is a leak fuel will siphon back into the tank. Could also be the fuel sending unit in your tank. I believe yours will have a check valve that is suppose to stop this from happening as well. Air intrusion can also happen with incorrectly installed orings on the T fitting on top of the fuel filter. If this problem surfaced soon after a filter replacement start there and just for giggles reach under the canister and ensure that the drain is tight.
I actually purchased this car with a starting problem. I figure I would be able to fix it if I put the time and effort into it. I have recently changed the fuel filter and the same problem occurs. I see no fuel leaks nor when I stick my hand under the cansiter do I feel any liquids and it will no tighten any further.


Thanks for the input in any case.
Any other suggestions?
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Old August 14th, 2007, 15:36   #7
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If the return lines are old, change them. This problem is not fuel leaking out, but air leaking in, which makes it somewhat more difficult. If there is a slight hole, it allows air in, and the fuel goes to the tank (slightly downhill there - so slight suction). There is generally no signs of a real fuel leak unless it's under the cannister, which you've checked.

If this has been chronic, and the fuel return lines look almost new, I'd very carefully look over the "t" - perhaps even replace it. A slight nick in it where the orings go, or slight crack in it, can cause this type of problem.
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Old August 14th, 2007, 15:40   #8
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Quote:
Originally Posted by mikica
That sounds to me like deposits on intake valves.You should have compresion checked.The glow plugs are only turned on only at temperatures below 5 degrees.Also it would not be bad to check injection timing.
How do I do a compression check as well as check the injection timing?
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Old August 14th, 2007, 15:54   #9
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Quote:
Originally Posted by rdkern
If the return lines are old, change them. This problem is not fuel leaking out, but air leaking in, which makes it somewhat more difficult. If there is a slight hole, it allows air in, and the fuel goes to the tank (slightly downhill there - so slight suction). There is generally no signs of a real fuel leak unless it's under the cannister, which you've checked.

If this has been chronic, and the fuel return lines look almost new, I'd very carefully look over the "t" - perhaps even replace it. A slight nick in it where the orings go, or slight crack in it, can cause this type of problem.

Are you talking about the fuel lines under the car? Are there lines under the hood that should be replaced as well?
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Old August 14th, 2007, 16:04   #10
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No - the lines that take the excess fuel from the injectors back to the filter.
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Old August 14th, 2007, 19:08   #11
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Most likely the problem is the pump timing is off. Use the Vag-com list above the forums for someone in your area and ask them to help you. IF you were a bit closer I would do it. But 8 time out of 10 that will be the problem. Bubbles are normal in the fuel line and unless the T valve O-rings on the Fuel filter are letting air in that is not your problem.
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Old August 15th, 2007, 12:17   #12
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I did some more looking and I found that although the bubble may start about an inch, if I crank the engine for a good 10 seconds and stop it before it starts, it will grow to about the size of the clear fuel line. However, once it goes away the engine will start. When I left it running for a few minutes, I can turn it back off most of the bubbles are gone and it will start with very little (only about a second or 2) complaining. If I turn it off immediately after it start and try to start it again it will struggle.


The fuel lines as far as I can tell have no crack in them. How would I test to see if I needed to get a new connection piece?

Also, I found someone in the area who will be able to run his Vag-Com on my car next week.

Thanks.
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Old August 15th, 2007, 13:23   #13
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I'd be tempted to "throw" a new "t" connector on it. Look at the one you have with a magnifying glass - see if there are any cracks to be seen.
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Old August 15th, 2007, 14:02   #14
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2000 VW Jetta TDI
160k miles
43mpg average
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Old August 15th, 2007, 14:16   #15
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Hmm... I left my car off for a couple of hours and the fuel line has small bubbles however it still has problems starting... I just thought I'd give an update.

Another thing to add is that when it finally does start it pours a lot of smoke out of the exhaust.
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