Hard start problem- 2004 VW Jetta

I have a 2004 Volkswagen Jetta TDI with a hard start problem that has been going on for 2 years. It is really difficult to start the first time of each day and then it is fine after that. It is worse when it is cold out, but happens even in the middle of summer. It cranks and cranks and cranks until it finally catches (Around 5 mins) I have taken it to 4 different mechanics and nobody can seem to figure out what the problem is. It is wearing out batteries. I have put a lot of money into trying to solve this problem. We have replaced the fuel filter, battery (twice), the fuel pump in tank as well as pump and supply relays, glow plug relay, and coolant temp sensor. We have also checked the glow plugs and the ECU wiring harness, and cleaned the carbon from the EGR valve and intake manifold flap. Any suggestions? This is a wonderful car, but I need for it to start reliably and not be such a money pit.

have you brought it to a local guru?

do you have bubbles coming into your fuel line? My guess would be a cracked fuel sender

Yes, there are bubbles coming into the fuel line actually. I'll have to check that out.

Thanks for replying

do you have bubbles coming into your fuel line? My guess would be a cracked fuel sender

Bubbles

You say you have bubbles & have replaced fuel filter, but did you replace the thermostatic T?

It important to check that the o-rings are replaced, are the correct size and it the right order on the T to prevent air leakage. You could try by passing the Tee with a barbed brass or plastic coupler and see if that helps.
Have you ever had the timing checked on your car? for best operation it should be as close to zero degrees (+ or - .5 degrees) it if out more than 1.5 degrees it will cause hard starting.

Had that issue on a friends 04 and it turned out to be a very weak in-tank lift pump. New pump fixed the problem immediately. Have also seen the same issue on another PD but the tandem fuel pump was the culprit on it.

TW

How did you check the glowplugs? Did you remove them to verify the tips are still in place?

TurbineWhine said:

Had that issue on a friends 04 and it turned out to be a very weak in-tank lift pump. New pump fixed the problem immediately. Have also seen the same issue on another PD but the tandem fuel pump was the culprit on it.

TW

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I would agree with this assessment. The in tank pumps fail quite often. The tandem pumps leak sometimes too. The intank pump is about $250 and the tandem pump about $350 and the more difficult of the two to replace. So you might want to try in-tank pump replacement first and if it does not fix the problem, rest assured that your money is not wasted, since the in-tank pumps fail, many before 100,000 miles (mine bit the dust at 46,000 miles).

Verify first the thermostatic T and fuel lines are leak free before you start replacing pumps, though.

--Nate