98 tdi intermitantly starts but roughly

i have a 1998 jetta tdi 125k. put on a new timing belt and water pump. ran strong for a week and progressively got harder to start in the morning until it didnt start at all. replaced the fuel filter and 2 dead glowplugs. had an air bubble in the fuel line after replacing fuel filter but got it to run after bleeding lines. but next morning it wouldnt start, turned over quickly. seemed as if it wasnt getting fuel. if i crack the injectors there is fuel getting to them. but even after the car running and driving strong, i see a airbubble in the line between the filter and injector pump. havent been able to get it to start again. it will roughly fire and quit right away. running out of things to try, can anyone help me?!?!

Did you have reason to check the belt sprocket on the crank shaft? How did it appear during the cam timing belt replacement process?

... frozen water, slightly gelled fuel in line somewhere? Sounds like what just happened to me.
How much fuel in tank-low? Prime fuel filter with Diesel 911, red bottle, (add till it disappears down filter several times) then see if it starts. Getting much white smoke(unburned fuel) when it does sort of start? Id even put a few ounces in the tank.
Maybe nothing to do with recent TB work.
Unfortunately, I dont think the fuel companies are winterizeing the fuel as youed expect them to.

98 jetta no start

Lug_nut: i did not do the timing my self but the mechanic who helps me would have checked all that out to make sure everything was ok after the t-belt shredded, but thanx for the responce. also we checked the timing again and it was still dead on.
bolaB4V: I have plenty of fuel and it has been in a heated garage so I dont think that is the case. I am leading to believe that it may be an electrical issue

Does any one have a diagram of the relay panel and what each one is for? I changed the relay 109 I have read that is one to be notorious to go. Are there any others that can control the fuel injector pump or something that could cause my tdi issue??

Did mechanic use vag-com for timing/use new tensioner???? Sounds to me timing may be off or bad tensioner.....one question-are there paint marks on sprockets?

he did not use vag-com, he did put on a new tensioner. we checked the timing again locking in the in the injection pump, and the cam mark and flywheel marks where on. and yes the paint marks are still on sprockets.

I am curious of the timing being the issue because I did get it to start roughly a couple times and once started, it ran strong, but then I turn it off for an hour, and it turns over and wont start, feels like it has plenty of compression too, even though i never did a compression check/

If the crank belt sprocket had been removed, and reinstalled with the same bolt, the sprocket was not properly reinstalled.
The sprocket is not normally removed during a cam belt replacement. My question was a trick one.

Had a prior owner removed the crank sprocket and not properly tightened the replacement for that one-time-use stretch bolt, the sprocket can shift relative to the crankshaft.
The belt, fuel pump and cam could all 'shift' relative to the crank and piston TDC. And then the crank sprocket might shift back to proper position and all are timed properly again.

The way we checked the timing was locking in the injection pump to zero, with that locked in, I can see that the slot on the end of the cam is level with the top of the head and the mark on flywheel is in center of window on top of tranny.
My question with the timing is; I got it to run after putting in the fuel pump and bleeding the injectors, it took a lot to get it to stay running, but once it was running, it ran strong, idled well and revved past 4k still sounding smooth. Yet the next day it started once, then not again. Can these symptoms still lead to timing? I appreciate all of your responses, thank you.

Your description helps eliminate shifting of crank TDC relative to injector pump and cam reference, so I'll head in another direction.....for now.

If the air bubble in the fuel line had disappeared (been vented back to tank) after the fuel filter has warmed and ceased the re-circulation, but was present again when you next tried to start the car, then I'd begin looking for leaks.
While the engine is running any small air leaks will not be a major problem. Once stopped those small bubbles congregate at the high points in the pump and injector pipes. Air is compressible and may prevent enough "solid" resistance to allow sufficient non-compressible fluid pressure on the injectors to allow them to pop open.

New finding> I am new to diesels so I'm not sure if the exhaust is important for backpressure or not. I saw today while looking for fuel line leaks, (not finding any obvious ones) that the exhaust was completely disconnected right after the CAT. can that be an issue with starting/back pressure?
As for looking for leaks, is it possible for a leak to be small enough for air to enter but no fuel actually leaks? If so what is a good technique of finding these leaks or are there common areas of weakness to check?

The fuel system is under vacuum right up into the injector pump. Any leak will be air getting sucked in, there is no pressure to make fuel leak out.
Look for oose clamps at the filter ports, cracked thermal T valve, missing O ring in the T.

The back pressure issue is moot when cranking at 900 rpm. With a completely open exhaust you have none. You presently have the ideal situation for power: Zero resistance after the turbocharger compressor wheel.

you all have been great with your responses thank you. I have a question, does my 98 tdi have a fuel pump back by the tank or it the injector pump the only fuel pump?

Only the injection pump in the engine bay on the 98 AHU/1Z engines.

...so i found that the lines between the filter and injection pump are leaking air in. Or the t-valve on top of the filter, if thats the right term. Does anyone know if I can just replace the lines with fuel line of same diameter or does it have to be the hard clear plastic line assembly that goes for over $100? Also would any one know where to find the t-valve, I have looked...

You can indeed replace with fuel line.

Here's the T. Ouch.

http://idparts.com/catalog/product_info.php?products_id=727

Wow-it's almost doubled in price-although it seems most parts for the A3's/B4's have seen steep increases over the last year.I think Bigwoode found a fuel filter w/ tee built in,but for the A4-can those filters fit A3's? It might alsobe worth it to find a kit to put the Cat filter in-I think that also eliminates the tee....

Issue with the A3s are the small diameter fuel lines on the return lines. They won't fit on normal barbs of an A4 fuel filter.

If you install the CAT filter, you will need to buy an A4 thermostatic T. Return lines don't want to slide over the barbs on the T. If you take a hacksaw and cut the barbs off, the hose will slide over the T enough to clamp.

BTW, I installed a CAT filter on an A3 earlier this week so it is fresh in my mind. With that one, we used a Kerma widget T. Still a PITA to slide the hoses onto it, even with the barbs cut off with a tubing cutter.

If you can live without the thermostatic T function, you can tap/plug the T hole in the CAT filter head. Then use a 1/4 inch brass joiner to connect the two return lines. Fuel would always be cold, so some sort of antigel treatment would be mandatory, IMHO.

thanks for all your help, I got a tough one here I am close to breakin down and paying the professionals....I got a joiner and bypassed the thermo tee that does indeed have a crack, pluged the top of filter, bleed the system right up to the injectors, Got rid of all the air!! then I cranked it and when I stopped there was just as much air right back in the corner before the injection pump. aaahhh!

When I turn the key on, should the injection pump move fuel? The injection pump clicks but does not make a familiar 'pump' sound, should it be doing more than clicking on? How can I test to make sure the pump is functioning correctly?

Injection pump doesn't move fuel till the engine turns. Out of curiosity, you said t-belt shredded. Did you pull the head? Valve damage?