Start, stall, start, stall @cold

My 2001 Jetta TDI (with 32K miles) has developed a starting problem whenever the temp is about 25deg F or colder. After the normal glow plug time, you hit the starter and it immediately starts running but then just as quickly, stops within 1/2 to 1 second. It usually takes 3 or 4 of these short cycle start/stops (including glow plug warmup) before it finally stays running. OBD shows no codes and the dealer appears to be at a loss as to the cause. It almost acts as if the fuel is being suddenly shut off. Does anybody have any idea what is going on here?

Does it seem to be okay once it stays running? Do you have any anti-gel additive in the tank?

Have you had the engine timing checked?

Possible relay 109 issue?

It sounds like the fuel is gelling, like it's not treated or cut at all.

Yes, I do add anti-gel solution to the fuel and I just replaced the fuel filter too. Even my '96 Passat TDI with 120K miles has never exibited anything like this. Once it (the Jetta) finally stays running, it does seem to perform well with normal power and pickup and will start normally after it is warmed up. Is there some kind of sensor that is going bad that could be telling the computer to shut it down or is the "ignition" switch the only direct link to the fuel solenoid shutoff valve?

Check timing. If OK than has to be fuel related. Not getting enough fuel or is being shut off.

Although it doesn't fit the normal scenario, you could check inside the egr valve to make sure that it is not too gunked up so that it might make the anti-shudder valve inside it stick.

I just replaced the fuel filter too

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<font size="2" face="Verdana, Helvetica, sans-serif">Maybe double check this for leaks.

Thanks to all for the great tips. I like the idea about checking the timing. (You know, they say, "timing is everything" and I'll bet that's especially true for a cold diesel.) That does sound like a reasonable place to start since it probably could have changed slightly since it was new because of normal wear and/or belt stretch. I will post again when I find the real "cure".

Steam man

Have you thought about checking the GP afterglow system. It almost sounds like the GPs are not supporting combustion during the cold start phase.

FWIW

Joe

Check the coolant temperature sensor ...

Will try to study up on the after glow system from the Bentley manual I have for my '96 Passat. Hopefully the system hasn't changed and will be the same for the '01 Jetta.

How long do the GPs stay on in the first place? Just a little bit or at least 5 seconds?

Glow plugs stay on about 5 seconds, up to about 10 seconds if it's a lot colder like around 0 or 10 below. It will always start right away when you hit the starter but it stops just as quickly. You have to go through whole process again (usually 3 or 4 times) before it finally stays running.

Originally posted by GoFaster:
Check the coolant temperature sensor ...

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<font size="2" face="Verdana, Helvetica, sans-serif">ditto

10 seconds if it's a lot colder like around 0 or 10

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<font size="2" face="Verdana, Helvetica, sans-serif">ditto