[Vwdiesel] Injection Pump Blues

[Charlie Smith]

Your procedure sounds good for replacing and timing the pump.  I'm going
from memory from 10 years ago, so my figures may not be exactly right.

Some of the injection pumps called for an earlier timing.  What was it,
yellow spot pumps were (?) 1.15mm?  I don't remember exactly.

Your symptoms sound like retarded timing.  I'd try the 1.15 timing and
see what happens.

The sudden increase in power at some raised RPM is happening when the
internal pump advance mechanism kicks in.  Since this pump is 'rebuilt',
this may have been 'adjusted'.  I'm not recommending you get into this
unless you are very careful with your performance measurements after any
change ...  but here's the deal on the advance in the pump.

  The pump advance is actuated by raised internal fuel pressure in the pump
  as RPMs go up.  There is an advance piston, with a spring and shims, under
  the 1" cover on the lower front of the pump.  Changing the shims even a
  little bit significantly affects when the internal injection advance
  kicks in.

Let us know what happens when you advance the static timing a bit.

    - Charlie


  Charlie Smith   charlie at elektro.cmhnet.org  614-471-1418
  http://www.elektro.com/~charlie      Columbus Ohio   USA
  http://www.elektro.com/~audi     photos & technical info

  95 S6 Quattro  -  24 PSI, RS2 6 speed, and other features
  97 Dodge Ram   -  35 PSI, 4x4 w/Cummins turbo diesel






Earlier, E. J. Gilbert wrote:
>
> Hi Gang,
>
> I am asking for some diagnostic assistance. I recently changed out a leaking fuel injection pump with a used pump which had recently been resealed and calibrated.  The engine is running worse than it ever has with low power, excessive vibration, and high fuel useage.  The "new" injection pump is noisy.  Perhaps something in my technique is the cause of the problems.  I am going to list my actions step by step to see if anyone has an insight into the engine problems.
>
> 1.  Removed the valve cover and top belt guard.
>
> 2.  Set engine on top dead center with the valves pointing up on the first cylinder and the cam slot parallel to the head.  Inserted fabricated metal bar in the slot.
>
> 3.  Removed injector lines, fuel supply and return lines and stop solinoid wire.
>
> 4.  Loosened the nut holding the cam gear in place
>
> 5.  Loosened the belt tension device and slipped the toothed belt off of the cam gear and the injector pump gear.
>
> 6. Loosened the nut holding the injector gear in place and removed the injector pump gear.
>
> 7.  Loosened the nuts holding the injector pump in place and removed the injector pump.
>
> 8.  Installed the new injector pump paying attention to lining up the seam of the injection pump with the groove on the injection pump mount.
>
> 9.  Installed the injector pump gear and rotated the gear until the slot in the tooth almost lined up with the mark on the pump mount. (was slightly to the left of the mark-CCW direction)
>
> 10.  Installed a 1/4" drive, 7/16" craftsman socket in the pump locking hole.
>
> 11. Slipped the timing belt back on the cam gear and the injection pump gear and activated the belt tensioner to hold the belt snug.  Slot in the cam gear still a little CCW from mark on mount. Removed locking socket.
>
> 12.  Finished tensioning the belt and checked that still on TDC.  Tightened the cam gear.  Slot in cam gear still a little to CCW of timing mark on mount.
>
> 13.  Removed bar holding cam in position.  Installed dial indicator device and rotated engine CCW until reading was constant (about 1/4 revolution).  Zeroed the dial indicator and rotated engine CW until TDC.  Dial indicator was reading about 0.75.  Rotated pump CCW until reading was 0.94.  Tightened pump mounting bolts.  Rotated engine CCW and then CW to verify that the reading was repeatable. Slot in tooth still a little to CCW from timing mark on pump mount.
>
> 14.  Filled injector pump with diesel, attached all the lines, covers,etc.
>
> 15.  Engine fired up after bleeding.  Idle is smooth, but low on power and suddenly increases speed after reaching a certain RPM in first, second, and third gears.  Very slow to drop back to lower RPM's.
>
> Can anyone spot a flaw in the technique used or something else for me to check before I condemn the pump?  Any suggestions would be appreciated.
>
> Thanks,
>
> E.J.