2005.5 TDI won't start

More problems with my car again. The past couple of days it has been difficult to start in the mornings. Yesterday, morning I tried to start it. Initially it sounded like it wanted to start. After several attempts, now it simple just turns over without any hint of wanting to start. Here is what I have done so far.

-I took the supply line off the fuel filter canister and hot wired the lift pump. I got a good amount of fuel going to the canister.

- I took out the glow plugs, placed my finger over the glow plug holes and it feels like there is compression.

- I looked at the fuel filter. It is dirty and has black soot all over it. I am replacing that next.


A couple of months ago I replaced the cylinder head. I don't know if this is coincident or not. I suppose my cam sprocket may have slipped a little or possibly the belt jumped a tooth? I am going to try to find an adapter to go in the glow plug hole so that I can check my compression. Anyone else have any thoughts?

Gad, I hope that's the oil filter You may have a biological growth in the tank, which completely plugged your fuel filter. I've never had it happen, so others with more experience may have to help. I do know they sell a diesel fuel biocide for these occurrances.

--Nate

Feels like there is compression...? From descriptions of oil painting peoples houses when the plugs were remove to eject oil I'd think your finger tip would be missing! That is one nasty looking filter. Where are you getting your fuel from?

I first saw that and went "Wow what a dirty oil filter". But that's a nasty fuel filter. When was it changed last and where you getting your fuel?

PS- What's up with EmirK1? He did the same thing the the Trsuted TDI mechanics thread.

I agree with the above- that filter is terrible. Change it, and it will probably be fine, but you should run a biocyde in the tank to kill the growth in it. The PD engines are very susceptible to small fuel starvation problems.

Certain types of algae can live in the space between a water and fuel layer in a dark fuel tank, so I suspect that you will need a water dispursant as well.

-Rich

The filter is probably 2 years old at least. I honestly can't remember the last time I changed it. The last time I changed it was due to the fact that it was cutting out on the Free Way. I have not had those symptoms however. The last time the car ran (a couple of days ago now) I had plenty of power. Maybe that growth in the tank adds HP. I get my fuel at Shell

Question - Should I go buy a gallon of fresh diesel and put that in the canister with the new filter? If there is some sort of bacteria in the tank, what kind of problem will that cause? When I poured the remaining diesel fuel from the canister (once I removed the filter) into a glass jar there were a lot of "floaties"

I think with a PD it is a great insurance policy to replace the filter once a year whether or not you have traveled 20k miles. I just happen to drive enough to need to do it each October, so for me it is easy. Even my most recent fuel filter change, I think my car runs a touch smoother because fuel flows better. Fellow Passatian Alchemy once had his filter go amok on him and he had stuttering with the car that required towing. I always carry a spare filter, tools to change on the road if need be.

kpiazzisi: Yes, I would change that fuel out. Anything floating around in it will not be good for the lift pump or the life of the filter.

-Rich

I tried the new filter and no dice. The car still will not start. I just tore it down and confirm that the timing is correct. The valve timing is correct. I have the crank lockout inserted and the cam sprocket lock in place. The valve timing is correct, so I have no clue why this won't start. Anybody?

The tandem pump will have to be tested for output pressure next.

It is possible that if the vehicle was starved for fuel from the filthy fuel filter that the fuel gallery in the head is empty and must be refilled/pressurized. It will take a great deal of cranking to fill it again. (Crank bout 45 seconds, then let it sit for 5 minutes and repeat).

-Rich

Rich,

I am doing what you suggested. I have been pulling the glow plugs out to see if there is diesel fuel on them. I don't know if this is a valid indication or not. I know with the gas engines if you keep cranking and it won't start the plugs will be fouled with fuel. So far my glow plugs are completely dry after all this cranking. I don't think I am getting any fuel.

I will try cranking it again in a few minutes. Please keep checking this post. How do I go about checking the tandem pump?

You can use a mityvac to draw a vacuum on the return line from the tandem pump where it connects to the fuel filter. Vacuum that for several minutes while cycling the key. Then try to start it.

Tried filling an empty water bottle from the return line

I unplugged right after the fuel temp sensor. Basically it's where the bottom line on the tandem pump meets the aluminum fuel rail. I placed a water bottle there to catch the diesel. I cranked it about 5 times and only got about 1-2 teaspoons. There was actually more fuel coming from the other side of the open connection (the fuel rail). If this is the return line then why is the other side pressurized.

Both sides are pressurized. Always.
The lift pump will pressurize your fuel filter, and fuel will then go out both to the tank return line and the fuel rail return line.

So you have proven that your lift pump is workin

Pinch off (or block) the line between the fuel filter and the line you have disconnected.

Now crank the engine, you should get about 300 ml/min, 150 ml/30 seconds, 75 ml/15 seconds. If it starts, you should get about 1.2 lpm.

Read the side of your tandem pump. What brand name? LUK or Bosch?

Dan - I am glad I got you on board.

Dan,

Using my stop watch and a syringe I got exactly 35 ML in 15 seconds. It says Bosh on the side. Is this enough to make it not start? Can I clean the screen in this thing?

Dan is the Man!

Dan is the man. He called me to let it crank for 45 seconds straight to prime all the fuel lines. Apparently a tired tandem pump can take along time to get the air out of the lines. I am so glad it works! Thanks to everyone for there help

That is about half the flow rate that I get from LUK pumps. I have not had a good Bosch pump to test. The pumps are very different in design, so I hesitate to say that is a bad flow rate.

If someone has a good Bosch pump and get some flow rate data for us, that would help the community.

The fact that it did start about 35 seconds into a long crank indicates that the fuel rail was probably emptied - full of air. (Assumes good lift pump and good crank sensor.)

The fuel rail can drain back to the tank in several ways.
1) air leak on a fuel line under the hood.
2) leak past the fuel pump vanes (LUK) or gears (BOSCH), or the pressure regulator built into the pump.