2003 VW Jetta TDI 1.9 L. Hard starts

Good day all
This is my first post so if I dont do this right, my apologies. My VW has really hard starts when it has sat for awhile/ overnight. This occurs even in the summer months. Obviously worse in the colder months. I had my car checked/scanned by a mechanic. All checks came back good. It has a strong turn over, but hard time igniting/starting.
Any suggestions would be amazing. I went down the YouTube hole and I found one that said it could be a bad EO6 relay.

Jason

Defective / Leaking Tee at the top of the fuel filter would be my first guess.

That's the the thing that pops into top of fuel filter that has two hoses on each end?

Do you have auto or manual trans?

miningman's suggestion is a good one, particularly if multiple starts after running are without delay. The connections to the thermo-t can leak air, as well as can the part that inserts into the fuel filter. Some people have tried a coating of petroleum jelly around the sides - where the 2 o-rings are. Careful with the 2 hose connections - the barbs are plastic and will break if you're not careful. I've done over these and the other hose connections at the fuel filter with screw-type clamps and it helped reduce air bubbles in the intake hose to near zero. Not losing prime really helps startup. Other places for air ingress are in the fuel return lines from the injectors to the pump.

Additional points to check are whether the cam, crank, and injection pump are exactly in time statically. That is, if you line up the crank to TDC, do the cam lock and injection pump lock tools slide into place without moving anything?

These are simple yet effective things to check prior to adopting the throw-parts-until-fixed mode of auto repair. A lot cheaper as well.

Good luck and cheers,

PH

Does it hard start with a full tank of fuel?

Mydub1011 said:

Good day all
This is my first post so if I dont do this right, my apologies. My VW has really hard starts when it has sat for awhile/ overnight. This occurs even in the summer months. Obviously worse in the colder months. I had my car checked/scanned by a mechanic. All checks came back good. It has a strong turn over, but hard time igniting/starting.
Any suggestions would be amazing. I went down the YouTube hole and I found one that said it could be a bad EO6 relay.

Jason

Click to expand...

Fifteen year old seals on the pump can let air in while sitting also.

Where is injection timing set? Retarded injection makes for slow starts. And the injectors might be the culprit too. The it could be the starter as you get no fuel until IIRC 350 rpm. I have a 2003 Jetta wagon with messed up injectors. (PM if you want the story) . I am going to put in Drivbiwire PP520's as soon as I decide on what turbo I am going to put in

Yep, it starts the same way whether its fuller all most empty

Mydub1011 said:

Yep, it starts the same way whether its fuller all most empty

Click to expand...

The fuel tank? That doesn't affect starting unless you are empty. So, if you crank on it long enough, the engine will finally start?

--Hard starts after sitting a spell (long enough to cool the engine) can mean the fuel system has lost some of its prime. Fuel no longer is where it should be in the injection pump and/or injector lines. This will cause you to crank much longer as the fuel is pushed back to allow a start. If it's really bad, you won't be able to start the engine unless you use a miteyvac pump or pressure pump to get the fuel back to where it needs to be.

This may happen due to a leaky injection pump. Its seals can get old enough to allow air to enter the system and let the fuel drain back to the tank.

It can also happen at the thermo T on the fuel filter.

--Hard starts can be due to the timing of the injection pump, especially when its retarded. This is really evident in colder months. This can be checked out with the VCDS software.

-- I have found that hard starts can be exacerbated by an too lean (high number) setting of the injection quantity of injection pump.


The timing and IQ settings can easily be diagnosed with VCDS. If you don't have that you can find someone in your area that may have one. Here is a link for that. http://www.maptive.com/ver3/VCDS_Locator

Pop your timing belt cover off and see if it has diesel fuel residue on the inside and take a flashlight and look behind the injection pump sprocket to see if it is wet w/ diesel fuel. Mine got so hard to start, I thought I had an electronics issue because I couldnt see any fuel leaking out of the pump. Turns out my shaft seal was leaking and I couldnt see it.