[Vwdiesel] Fuel check valves

[Libbybapa at wmconnect.com]

The engine in my vanagon is a '91 ecodiesel.  I swapped the pump for a TD 
pump that has the aneroid.  Before I put the engine into the van, I was having 
trouble with my diesel jetta.  The inj pump started leaking.  I swapped the 
ecodiesel pump and lines to the jetta.  The eco pump promptly began leaking.  I 
found that there was a slight blockage in the fuel return line.  I got another 
used inj pump from a friend.  I swapped it on, and swapped the fuel check 
valves with the eco valves (they were longer, and allowed me to use the eco lines). 
 When I began running the car it was obvious that the fuel was turned WAAAYYY 
up.  Billowing smoke.  Jumping around if the accelerator was touched.  I 
adjusted the smoke to a reasonable level (about three full turns on the fuel 
screw).  When I got around to putting the eco into my vanagon, I needed the eco 
lines from my jetta, as they had the extra bend to clear the aneroid (despite the 
fact it never had an aneroid previously).  I also needed to swap the check 
valves, as again they were significantly longer and matched the lines.  When I 
put the shorter check valves with longer lines on the jetta, I noticed that the 
fuel was turned down.  I had not done anything to the pump except change the 
check valves.  When I got the TD running it also had the billowing smoke.  The 
pieces are staring to gel, it's the check valves.  I assume that they change 
the internal pressure, but I want a bit more of an understanding.  Is the hole 
in the outlet bolt the only thing that meters pump pressure?  Is the hole in 
the bolt different in different pumps that have different check valves?
Andrew