2004 Jetta TDI won't start / run when air temp is in the 30's.

Hi All,

My son has a 2004 Jetta TDI which he had some start and run issues with last winter however as soon as the air temps warmed into the 40's / 50's it was fine - it has started and ran fine all summer. This morning the air temp was in the high 30's for the first time and it started but died a couple miles down the road - same as last winter. Occasionally, it simply won't start at all if it is in the 20's to single digits. But primarily it will start and die later either on the road or in the driveway.

It doesn't have to be freezing for this to occur, in fact this morning was 38. I would estimate that it will infact start most of the time and die while he lets it warm up ... minutes later.

As the daytime temps warm, it has never failed to start right up when we try it later. If he keeps it inside out of the cold air, it has never failed to start and run.

Moisture is not a factor today and as for precipitation in general, it doesn't seem to matter.

Wondering where to start?

Thanks

Possible Glow Plug/Harness issue. Coolant temp sensor. Do you have a vag-com ?

Need a little more information...
How many miles?
Any maintenance done before the problem started?
Any CEL's?

Make sure it has the latest software, glow plugs, and glow control unit per TSB/campaign/warranty extension failtrain fiasco.

No Vag-Com...no check engine lights. It has roughly 150,000 miles and he had the timing belt, water pump, pulleys etc replaced shortly after he bought it in early 2012. He also had the clutch replaced this past spring. No issues at all other than it doesnt want to run in cool weather. It typically always starts and then 5 or so minutes later dies whether moving or at an idle. If then the day warms up to the 50s-70s it starts later that day. It will be close to 70 when I get home and he gets home from work...no doubt it will fire right up later this evening.

Am I correct in assuming that the glow plugs are only required to start the vehicle and aren't typically necessary for it to continute to run...especially in mildly cold weather?

When it began last year, we kind of attributed it to water in the fuel system or tank as it was during a cold spell. However this morning as I said it was 38 degrees and he only traveled a mile or so in town.

If it is hard/impossible to start cold, then my above post may apply. If it dies after it has already been running then you have another issue. Could be lift pump, fuel leak (air getting in), etc.

oilhammer said:

If it is hard/impossible to start cold, then my above post may apply. If it dies after it has already been running then you have another issue. Could be lift pump, fuel leak (air getting in), etc.

Click to expand...

Thanks for the comments Oilhammer, typically he doesn't have a problem with it starting - it dies several minutes later and won't restart. If it remains cold/cool that day it likely won't start until we get it inside or the air temp warms up. Would cool weather make a leak or lift pump problem more pronounced?

I have a 2000 with 265,000 miles, I have never experienced the problems he is having.

Your 2000 has a totally different fuel system. I suspect a leak in the fuel system, when the engine/car is cool, that allows air to get it and essentially the car loses prime.

What I would do is this:

Start and run the engine when you know it will likely act up, in a stationary controlled spot. When it stalls, pull the thermo-T off the fuel filter and see if the pleats are "dry" inside. If they are, then while that is loose, have someone cycle the key to ON. The lift pump should run for a second, you may even hear a slight buzz from under the rear seat, passenger side. If you get fuel in the filter, and the pleats fill up and it starts to come out of the hole that the thermo-T fits, you'll at least know the lift pump is still working.

When was the fuel filter last changed? If you don't know then it is time to change it. They are usually under $25, and easy to change.

Intank liftpump functioning properly?

Update...first of all thanks for all of the replys fella's. Well it started that afternoon with a temp of 70 degrees, but died several minutes later. He let it sit until last night and it started again, ran for a minute or two and died again.

So it isnt gettting fuel, though when it sits for a while it'll start, just wont run long. So, I assume I can pull the clip that holds the thermo-t in the top of the fuel filter and pour some diesel in to get it back home for further inspection - it is a half mile from home.

Sounds like this lift-pump/fuel pump is in the tank...does the tank have to be removed to access it?

Thanks

No, it's not too difficult to remove the lift pump. Pull up the right side rear seat and remove the three Phillips screws on the cover. Next you unplug the wiring harness and then the fuel lines, using a screw driver to unclip the lines. Mark the black plastic ring for reference purposes and you can try a block of hard wood and hammer to loosen the ring. Once loose I like to push down on the top of the pump to ease the unscrewing of the ring. Have a bucket and rags ready when removing the pump which will be full of fuel. Remove the seal from the old pump and place it loosely around the new pump. This seal is the only real tricky part. I don't remember if it goes in place on the new pump first or if it goes on the tank first. Keep the hammer and block of wood in the back seat in case you need to tighten the black ring some more when you go to fill up. It's best to change the pump when the tank is about 3/8's full, or slightly below the half way mark on the gauge. There is a better written how-to here somewhere, but this should get you started.

Is this the VE type engine? According to me the VE type engines does not have a lift pump in the tank.

2004 Jetta

Dieselmad said:

Is this the VE type engine? According to me the VE type engines does not have a lift pump in the tank.

Click to expand...

It is a BEW engine.

Thanks for the help guys...back on the road

And the fix was.....