ALH with rebuilt injection pump woes

[firehawk618]

Friend of mine works at a shop and they replaced the injection pump on a 03' ALH with a rebuilt unit from a local rebuilder.

They primed it up and the car started right up.

Steady stream of bubbles in the feed line.

When you shut off the car a long stream of air comes back out of the injector pump and the feed line is left with all air in the clear part.

When you try to re-start the car after it's sat a few minutes it has to crank 5+ seconds to re-prime and start.

To troubleshoot they put a feed line directly into a can of diesel and routed the return line into another can.

No air entering the pump when doing this and still when you shut the car off air flows back out of the pump.

Any suggestions? I'm thinking faulty pump.

When I was there I checked to make sure all 4 injector feed lines were tight and visually not leaking any diesel.

Thank you.

 

[firehawk618]

They are going to buy another new filter + thermostatic valve.

They have also tested the feed as well as return line all the way back to the tank.

They do not leak.

The sending unit was pulled out and bench tested. No cracks or leaks there either.

 

[firehawk618]

Turns out this pump came straight from VW.

 

[BobnOH]

Well you're on the right path, fuel system must be diagnosed as a whole. From the sounds of it, that's a substantial leak, shouldn't be too hard to find. Often overlooked are the little dribble return lines, if they are still factory, you may to refresh those with some 3mm Viton (or equal).

 

[firehawk618]

Welp here's the update. I hate it when posters don't update and I always try to update.

This unit was a rebuilt one bought straight from the VW dealer.

After testing everything twice I called them and told them what was going on.

They flat out said they all do that and you just have to work the air out.

I kindly explained I had done all that. I even went so far as to run clear lines from the pump inlet to a bucket and pump return to a bucket.

Non stop stream of bubbles. We're talking very foamy bubbles from the return line.

Run the car an hour. No change.

Shut the car off and air pushes back from pump through inlet line until the line is empty again which makes it hard to start until it primes again.

The parts guy said ok well then I guess we'll send you another one.

They did. I installed it. All is well now.

It was a bad rebuild unit right out of the box.

When the service writer girl called them initially a while ago the parts guy flat out shut her down saying they all do that and you have to really prime them. We won't send you another pump because it will do the same thing. *shaking my head

 

[BobnOH]

Par for a dealer. I know good rebuilders are scarce, but I would have thought something from VW would be tested. Never heard of this happening with a DFIS unit.

 

[casey823]

I had these same woes on a rebuilt pump, had 2 different ones installed with the same issues before I wised up and sent the pump to dfis, they will have my business for all my tdi stuff from here on out. My pump had to have cam replaced and everything, after all rebuild and shipping it was still under a grand for an 11 mm pump. DFIS is definitely the way to go. I learned the hard way after having to pay a shop labor on 3 pumps because I was working out of state!