How do I prime the injection pump?

My IP started leaking about a week ago. I read the links on replacing the top seals and heeded every warning out there. Unfortunately, the new top seals did not stop all the leaking, but it did stop most of it. There was still a good drip every couple seconds from the bottom of the pump, so I pulled the pump out.

From what I could tell, the leak was either coming from the head of the pump or from the cold start solenoid.

I have the entire seal kit for this pump and started replacing the seals one by one. I did all but the pulley seal and they seem to have gone together well. I made sure the pin was in the bleed off collar (as best I could).

I re-installed the pump and adjusted the timing with the lock/TDC method. I then used a vacuum to pull fuel up to the #1 cylinder return line. Finally, I started cranking and cranked until the battery died. I pulled the fuel line at the number 1 injector and it's dry. Should I have fuel by now? I'm concerned that I botched my pump while installing the seals, but it was a last ditch effort. It was functioning prior to the seal replacement.

I've never used biodiesel.

Put a vacuum on the top return line on the inj. pump and draw the fuel through. It will take a while.

I pulled it from the pump to the #1 cylinder. Should I be pulling it the other way? Which direction do you prime/pull?

I gather that pulling from the pump to the #1 cylinder takes fuel from the filter and fills up the low pressure side of the pump. Is this right? If I try to pull from the return line at the pump, coming from the #4 cylinder it will not budge because it will not overcome the spring in the injector. Can you help me understand what direction to pull and what the objective is?

Once I have prime, how long should I expect to crank the motor? I'm concerned about melting my starter, relays, etc... I have a good 5 minutes of periodic cranking in already (not the female kind). The uncertainty is killing me.

use the return line that goes from the pump to the filter. Attach at the filter. When you've gotten most of the air out, you could then try to crack open the lines at the injectors, wrap with a towel, and crank until fuel sprays out. Then retighten and go. Unless of course the timing is still off and it won't start.

Thank you. I'll do that. I need to see the fuel first before adjusting the timing. I happen to have a wierd pump. It needs to be skipped one tooth to get it to time properly.

I bled the lines from the filter, turned it over for a couple minutes and nothing. Not one drop fromt the cracked injectors. I took the top of the pump off to verify that the QA collar was aligned and it was. It is filled with fuel too. I then bumped the motor with the starter and observed that the plunger is fact spinning as it should. I don't know what happened to this pump, but I think it's shot.

I even tried cracking the lines at the output of the pump and not a drop came from there either. Is it time to thow in the towel?

You didn't unplug or open the shut-off solenoid when you were working, did you?

I had to unplug it to take the pump out. I also disconneted it at the solenoid. I reconnected it at both ends. I wondered about that bad boy. Are they normally open or normally closed? It seems normally closed would be the smarter engineering design.

I did not take it out. I figured if it leaked, I could replace it in place. Is there a way to test it? I noticed that the fuel has eaten some of the silicon off the top.

Sounds like you are having alot of fun with that pump. I had some issues with mine and needed to replace it in the end. I used a large syringe to prime the pump pushing fuel directly into it. When I could not get anymore in, I hooked everything back up and it started in a couple of cranks.

If you are in need of a new pump, I found the cheapest price online. Drop me a note if you want the info where I got the pump.

tverhoeven@3web.com.

tony

Normally closed. Is it getting supply voltage? Can you hear it click when you turn on?

I will check the solenoid operation when I get home tonight. That would be a great find. Perhaps I bent a pin or brok a wire when wrenching around in there.

tverhoeven, I was up until 2am trying to get this pump to run after rebuilding it in two stages and going through the timing set-up only to find the pump stopped working. I went to bed stinking like a truck stop. Now I'm faced with shelling out $400 to $1000 for a replacement. If I were married to this car I would be filing for divorce. The love is gone.

I do appreciate the help.

The solenoid is good and getting power. I pulled it and verified that it pull tight when you turn the key. Dang. That would have been a beautiful fix. I think I'm going to pull it tonight.

I just had what alcoholics refer to as a moment of clarity. I found the problem. A spacer that lies behind the piston must have fallen when I reassembled the head. In the picture below, you can see it broke in to 4 pieces. This screwed up the alignment of the piston. Does anybody have a junked pump around? This has to be a 5 cent part. I would hate to buy a whole pump for this.

I found the spacer part at the local Bosch repair place. It was $10. It fixed the pump and the car is back on the road. Thanks for the moral support, all! I feel like I've learned a lot about diesel injection pumps. The pump is now dry as a bone.

The key to rebuilding the head is to thread the pulley nut back on the shaft and place the nut in the vise. I used a dab of grease on the washer as I installed it the second time. It did not move. It worked for the to hold the return spring pins in as well. The priming trick previousely mentioned worked like a charm.

Go slow, start with a clean workbench and check the pump for smooth rotation prior to installing (easy to do on a vise). It is not rocket science by a long shot. It's definately not worth buying a $1000 pump.

Having a Vag-Com was critical. The rest of the seals were simple.

If I can help anybody in the future, please fire me a note. Thanks again!

Thanks for the followup, Pillote.

I suppose my A3 will have IP problems somewhere down the road, and your persistence & eventual success will inspire me to fix not replace.

Good job!

Simon