Why can't I bleed Diesel through the new pump I have fitted?

Tiny
CHRISFIXES
  • MEMBER
  • 1999 AUDI 80
  • 125,430 MILES
I have renewed the Diesel Injector pump on my TDI Audi 80, but the engine will not start. There is diesel up to the pump and no air bubbles in the lines to or from the pump, but the diesel is not coming through the pump to the injectors. Do I have to "marry" the injection pump to the engine management or is there another solution?
Wednesday, May 9th, 2012 AT 8:33 PM

7 Replies

Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
You may need to apply air pressure to the pump to help draw fuel through for the initial prime, ensure all lines are tight as if not you may be drawing in air as well and check all electrical connections on the pump one will be the fuel shut off solenoid.
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Wednesday, May 9th, 2012 AT 10:19 PM
Tiny
MHPAUTOS
  • MECHANIC
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That should read air pressure in the tank. Sorry.
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Wednesday, May 9th, 2012 AT 10:19 PM
Tiny
CHRISFIXES
  • MEMBER
  • 4 POSTS
All electrical connections have been checked and are working. There is diesel under pressure at the pump, but there is no diesel coming through to the injectors when engine is cranked over. When the return line is opened and the ignition is switched on, the fuel pumps through for about 3 seconds, back to the tank. Therefore I don't think it is a bleeding problem. I need more info on the electronics manageing the pump.
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Thursday, May 10th, 2012 AT 6:35 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
I would crack the lines loose one at a time till you get a good flow while cranking. You will have to bleed at least 2 lines for it to fire and bleed itself the rest of the way.

Why did you replace the pump? Did you time it correctly.

Roy
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Saturday, May 12th, 2012 AT 1:22 AM
Tiny
CHRISFIXES
  • MEMBER
  • 4 POSTS
The pump timing is spot on. I have cranked with the pipes to the injectors loose and no diesel comes through at all. The engine runs when Brake cleaner is sprayed into the air intake, but the system will not bleed. I really suspect an electrical fault with the throttle control, but I don't have a wiring diagram or a computer fault reader. The ariginal pump was replaced as it was worn out and couldn't be repaired
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Sunday, May 13th, 2012 AT 9:24 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Did you use a new or used injector pump?

Roy
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Sunday, May 13th, 2012 AT 2:48 PM
Tiny
CHRISFIXES
  • MEMBER
  • 4 POSTS
There is power to the shut off valve and the pump is a reconditioned unit which I returned to the supplier. They tested the pump whilst I was there and showed me that there was nothing wrong with it. I am at a loss as to why the fuel doesn't come through to the injectors. It is the same pump as the one shown above. Where could I get a wiring diagram for the throttle control?
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Monday, May 14th, 2012 AT 6:42 PM

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