Injection Pump Losing Prime

2003 Jetta TDI 69,000mi

Here is the problem...

The car runs just fine, but has a lot of bubbles in the fuel line and the IP is losing its prime, making the car very difficult to start. Its obvious that there is air in the fuel line b/w the filter and IP. When you shut the engine off the fuel from the IP rushes back through the fuel supply line/filter and back towards the tank. Checked the fuel tank in case there was some sort of blockage and it was clean as a whistle. The IP is not leaking and there are no fuel leaks anywhere. Seems like the only thing left would be an air leak in a fuel supply or return line, but wouldnt there be a fuel leak somewhere if this were true? This same problem has occured with 2 different fuel filters. Occured while a aftermarket fuel filter was in the car and while a VW filter was in the car. The kicker is that this problem only occurs when i put regular diesel fuel in the car. I have never had the problem when the car was running on biodiesel. Anyone have any ideas what is going on here? This work has been done by Import Autowerks in Raleigh, NC....I took it to them b/c they were on the forums mechanics list, but they seemed a little stumped by this.

I would check the front seal/ drive seal on the injection pump. If you are running bio and dino back and forth you will likely have a seal leaking. The only way to tell for sure if the seal is leaking is to pull the belt pulley off of the injection pump and look at it with a mirror, unless of course it is pouring out.

__. Were the o-rings on the "thermostatic T" on top of the filter changed with each filter change? Were they careful to not pinch them at installation? Yours is a classic case of leaking at the "T".

__. I once confirmed leaking o-rings on MzLauraLee's car by dribbling heavy drug-store-type mineral oil around the T. It temporarily sealed up the leak - you could see the air in the clear line dropping. After that, a set of properly installed o-rings was all it took.

Thanks for the replys. I retrieved my car from the mechanic since they seemed to be uninterested in working on it and have kept me in limbo for 2 weeks. I got the car in the driveway tonight and it seems like the T is not the problem. Took the engine cover off and there was a nice puddle of fuel below the pump head. I think we know what the problem is now. Seems like I told the mechanic thats what was going on and he didnt listen. Seal is on the way from dieselgeek.

leaking pump

When you run Bio the seals will expand then when you shift to diesel the seals will shrink. Stay with one or the other or you can expect leaks!

I initially thought it was the seal since it was happening when i switched fuels. I'm aware of what switching fuels will do. Seems like people are having problems just because of the switch to ULSD from LSD. Trippy!!!

Stevestyle67 said:

Seems like I told the mechanic thats what was going on and he didnt listen.

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Steve,

Who is the Raleigh mechanic you're referring to?

2003 cars have some weird check valve on the supply side line near the fuel tank. I have repaired one hard starting '03 by removing this check valve and replacing with a normal fuel line.

Steve,
Did that end up being the seal? I don't see any fuel leaking anywhere near the pump, but I did just recently change from bio to dino.

Been through 2 filters and did the o-rings on the T. It runs fine, but loses prime overnight, if I keep it inside it does not do it as bad. That tells me that maybe it is the seal you spoke of because it might be shrinking with the cold.

I still do not see any fuel leaking.

Thank you.

The input shaft seal causes more of a loss of prime with some slight leakage. My experience has been to replace the input shaft seal, head seal, top seal and injection quanity adjuster seals and you will be ok, provided your car is running fine, otherwise it won't make any difference in the way it performs just stop the leaks and loss of prime. The input shaft seal replacement requires some expertise and must be done properly or you will have problems. This will require removal of the pump and resetting the timing.

Yes, it was the head seal. I went through a fuel filter as well. I figured it was the pump head seal and I really did not want to do the work myself, so I took my Jetta to Import Auto Werks in Raleigh and told them what was going on. Well they didnt listen to me and let my car sit for 2 weeks until I forced them to look into the problem. Well they couldnt figure it out (knuckleheads), when I took the car home I noticed a little fuel leaking around the pump head so I went ahead and ordered a new Viton pump head seal. Using the intructions for replacing the seal posted in the 'How To's' sticky in the TDI 101 forum I was able to replace the seal. Car has started perfectly ever since and I gone between biodiesel and regular diesel several times without repercussions.

The point is....

Definitely get a new Viton seal and follow the directions for replacing the seal. Taking your time is the most important part of the procedure...

Thanks Steve,

I am going to order one. I fixed the pressure valve over the weekend but am still having issues.

I am going to order one of the viton seals for both of my Jettas. I don't see any leaking, but that doesn't mean its not sucking air.

Have you had any issues with the fuel hoses or the small return hoses?

I run B100 most of the year. Oddly enough this started when I switched to Dino 100% in filling up 1/2 way to get ready for winter.

If that doesn't help then it's time for the other seals, and do a timing belt and water pump at the same time.

Thanks guys!

Similar issue here.

Previously used B99 for many tanks, but the 100+% price differential ($2.15 ULSD vs. $5.40 B99) caused me to go back to ULSD D2. It was only 2-3 tanks into using ULSD D2 when it began difficult starting issues. It doesn't even want to start now.

Pulled the fuel filter Tee and see fuel at the top. Can't make out if the clear fuel supply line is completely full or completely empty, but it doesn't change while sitting or when trying to start.

TDI battery hooked up to my running F250 diesel truck, so I'm pretty sure the starter was getting enough juice.

In trying to get it started I bled each injector line. It used to spray fuel when cracked open, but now it just barely dribbles out.

No obvious signs of fuel puddles below/around the pump, but with the pictures provided, I'll take a closer look.

Does it sound like I have leaking seals? Or do I have a greater problem?

Which one (or both) of these kits do I need? I do intend on going back to B99, but not at the current price differential.

http://www.dieselgeek.com/servlet/Detail?no=443
http://www.dieselgeek.com/servlet/Detail?no=430

02AutoWag said:

Similar issue here.

Previously used B99 for many tanks, but the 100+% price differential ($2.15 ULSD vs. $5.40 B99) caused me to go back to ULSD D2. It was only 2-3 tanks into using ULSD D2 when it began difficult starting issues. It doesn't even want to start now.

Pulled the fuel filter Tee and see fuel at the top. Can't make out if the clear fuel supply line is completely full or completely empty, but it doesn't change while sitting or when trying to start.

TDI battery hooked up to my running F250 diesel truck, so I'm pretty sure the starter was getting enough juice.

In trying to get it started I bled each injector line. It used to spray fuel when cracked open, but now it just barely dribbles out.

No obvious signs of fuel puddles below/around the pump, but with the pictures provided, I'll take a closer look.

Does it sound like I have leaking seals? Or do I have a greater problem?

Which one (or both) of these kits do I need? I do intend on going back to B99, but not at the current price differential.

http://www.dieselgeek.com/servlet/Detail?no=443
http://www.dieselgeek.com/servlet/Detail?no=430

Click to expand...

Just an update. All is well with the $9 head seal.

Dieselgeek instructions are pretty straight forward. No need to feel worried. Couple things to add (stress) in regards to dieselgeek's installation instructions:

1) Order a new oil dipstick tube. You'll be in and around that area and you don't want to have a broken dipstick tube without a replacement. I broke mine while changing the seal and was fortunate to have another tube on the shelf.
2) A fishing hook is great for retrieving the old seal. Dieselgeek suggests a mechanics pick, but I don't have one. The fishing hook is great because it'll grab the seal and hold on to it well.
3) The supplied tool was of no help to me. I talked to Dieselgeek during my install specifically about the tool. It's a flat threaded bolt and was designed this way so that it will not cut your new seal. My problem was that these flat threads would not screw into my pump head. I didn't want to force it for fear of stripping the pump head. I instead used the existing bolts, but only backed them out far enough to gain access to the seal...the fishing hook and paperclip are essential during this step.
3) As always, a tool to pull vacuum is great for priming the pump once the job is done. Be sure to have a can of diesel (or other fuel substitute) as the empty pump will suck the filter dry. I was pulling vacuum for minutes before I realized that I have to keep topping up the fuel filter.

Start to finish was about 1.5 hours (2 hours max)...and about 15 trips back into the garage for tools. A second set of hands (just to hold the seal with the paperclip while backing out the bolt) was need for all of 2 minutes.

Yes, it was the head seal. ... I really did not want to do the work myself, so I took my Jetta to Import Auto Werks in Raleigh and told them what was going on. Well they didnt listen to me and let my car sit for 2 weeks until I forced them to look into the problem. Well they couldnt figure it out (knuckleheads), when I took the car home I noticed a little fuel leaking around the pump head so I went ahead and ordered a new Viton pump head seal. Using the intructions for replacing the seal posted in the 'How To's' sticky in the TDI 101 forum I was able to replace the seal. Car has started perfectly ever since ,...

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Anyone can do it. I honestly believe that.

Have you checked the Thread here about the fuel sending unit and the restrictor and non return valve. I had the same problem with my 2002 Beetle on WVO in very cold weather. Too much vacuum in the fuel supply line which would pull air in around the fuel line seals. I did the repair - drill out the restrictor and remove Non retuen valve. If you have the "C" fuel sender unit, you should do the mod.

How do you know if it's a "C" unit? I was thinking of doing this to my 00 Jetta TDI ALH it's loosing prime when it sits for a few days.

Wayne, you have to go back under the seat and remove the cover, I mean the screw-down retaining ring, and look at the part number on the sending unit. It wasn't difficult on my wagon.
Larry

Wayne, other possibilities: pump head seal
Thermostatic tee valve O-rings

Fuel Injector return lines ?

I have a similar hard starting problem, but mine only appears when the fuel tank is at 1/4 or below. When it happens, I do notice bubbles in the line, however I haven't noticed any fuel leak - haven't really looked that good either, since I usually park on gravel. I'll have to put some cardboard or something under the pump to see if I can find a leak, but why would it only be a problem when the fuel level gets low?????

I don't know MW ... perhaps you should go through the exercise of pulling the fuel sending unit? Verify its part number / revision, inspect it to make sure it doesn't have a bunch of crud, in back of the check valve ...

Wait a minute -- can you clarify about how often you drain the bottom of your fuel filter? Or, is it a really old filter that didn't ever get changed?

Larry

I changed the fuel filter a couple of months ago, ahead of schedule (I change normally every 20k miles). I thought that did the trick, but it simply coincided with having more than 1/4 tank of fuel. I think checking the sending unit is a logical place to start looking. I know on my old 99.5 I replaced it with the Canadian version and drilled out the check valve, after a bad gelling experience.

I know the older IDI pumps if the pump lost prime it was due to a worn pump shaft bore in the housing. Overnight the pump will drain into the tank.

The easy fix is a lift pump or external fuel pump.

Fuel level

That's good Mike, that your filter is proper.
I don't know why, but on my vehicle (2002, 165k miles), it also seems to run slightly smoother (quieter) when the fuel tank is 1/2 full or more.

I had assumed that since we have the 2-stage pump up front and no lift pump, that it was a little bit more difficult to pull the fuel into the IP when there's a minimum of forward pressure from the bottom of the sending unit.
The IP is working against some potential flow restrictors (check valve, filter, etc.)
Anyway, this pump has served me well (aside from the seals giving out ... I've replaced the head seal, top and middle also). Larry

mwalters said:

I changed the fuel filter a couple of months ago, ahead of schedule (I change normally every 20k miles). I thought that did the trick, but it simply coincided with having more than 1/4 tank of fuel. I think checking the sending unit is a logical place to start looking. I know on my old 99.5 I replaced it with the Canadian version and drilled out the check valve, after a bad gelling experience.

Click to expand...

I"ve got a 2002 TDI Beetle, 59,000 miles, just had the timing belt changed. Car was getting harder and harder to start. Now it just won't start at all. Looked up the issue here, removed and cleaned the intake manifold. Also changed the fuel filter, bled the fuel system and it still won't start. I did notice a fuel leak where the injection distributor meets the the injection pump. Can I just remove the fuel ditributor from the back of the injection pump and replace the o-ring, or does it all have to come out??
My mechanic says the guy who rebuilds his tdi injection pumps charges $1200. I don't want to pay out the nose for a $25 o-ring kit, you know. Any help would be greatly appreciated.

-Josh

gottattooz said:

I"ve got a 2002 TDI Beetle, 59,000 miles, just had the timing belt changed. Car was getting harder and harder to start. Now it just won't start at all. Looked up the issue here, removed and cleaned the intake manifold. Also changed the fuel filter, bled the fuel system and it still won't start. I did notice a fuel leak where the injection distributor meets the the injection pump. Can I just remove the fuel ditributor from the back of the injection pump and replace the o-ring, or does it all have to come out??
My mechanic says the guy who rebuilds his tdi injection pumps charges $1200. I don't want to pay out the nose for a $25 o-ring kit, you know. Any help would be greatly appreciated.

-Josh

Click to expand...

Go to page one and read what I had to say in post #13 and #14. Look at the pump seal installation procedure I linked to.

Well I finally got a chance to pull the fuel sender - it was already the H version (the Canadian one without the check valve). It was pretty cruddy, but I couldn't really find anything wrong with it. I cleaned it up and put it back in, but I still had the problem. So, I ordered a new H version and drilled out the little triangle of plastic in the inlet tube just to make sure there was no restriction. Presto, less than 1/4 tank this morning and it cranked right up like normal! There must have been some crud in the old one I didn't get, or else a crack somewhere that I didn't see. At least it wasn't the IP!!