Volkswagen: 75 vw bus1.8 ltr fuel injected, fuel leak, air flow control, fuel injection system

Question
just purchased the van and has fuel leak under engine (i already knew).  was told to repair i must go through the rods underneath and there is a shim needing replaced between the head and jug. i am searching locally for manual and have chilton vw book for several types, seems general. cane you give me better direction and explain parts little more specific.  read one of your answers and thought maybe fuel pump dripping or something.  thanks.  p.s. not driving the van.   paul

Answer
Hi Paul,

The shim and between the cylinder head and jug wouldn't necessarily cause a fuel leak.   This would cause a lack of compression, or no compression at all.   

1) Perform a compression test on each cylinder. A compression gauge is around $35.00-$40.00.   If you have between 85-110 PSI on each cylinder (no more than a 25 PSI swing between the cylinders) you have no need to touch that shim.

2) Replacing the shim requires a SIGNIFICANT amount of engine disassembly, as you need to take off the cylinder head, and it's best done with the motor out.  Thus, the importance of the compression check.

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Fuel Injection System

Your 75 1.8 Bus is equipped with AFC Fuel Injection.  (Air Flow Control).   The fuel is routed as follows:

1) From the tank, the fuel is sucked out by the pump, which is located on the driver's side rear side of the frame. (it's round, cylindrical, and about 8 inches long with two wires on it, one wire grounds to the frame beside it.)

2) From the pump, the fuel goes to a fuel filter which is a white-boxy looking thing right next to the fuel pump.

3) From there, the fuel line continues through the rear engine shroud (Drivers side if you are looking in the engine.) It comes through a little hole with a rubber grommet to keep the fuel line from rubbing on the metal, this connects directly to #3 fuel injector. (driver side closest to rear).  

4) From there, it converts to a metal line which feeds number 4 injector, continues as a rubber hose again to the front middle of the engine to another injector. (this is your cold-start injector).

5) The fuel line continues from the other side of the cold start injector to the metal line that feeds number 1 & 2 injectors. (passenger side)

6) After it feeds 1 & 2, it becomes a rubber line again and connects to a round-looking cylinder with a small vaccuum hose connected to it.  This is the fuel-pressure regulator

7) The fuel circuit concludes by one final rubber hose connecting  the other side of the fuel pressure regulator, back to the tank.  This is where the excess fuel is returned.

Note:  If you are replacing these rubber hoses (recommended) make sure you use Fuel Injection hose only.  Regular fuel hose will burst under the pressure delivered by the electric pump.

Summing up:

1) Check the compression to ensure that you indeed need to replace that round shim.   Also, check the torque settings on the cylinder head if you have a compression problem. (you want to eliminate any causes of low compression/leaking fuel), before you tackle pulling the engine/head).   Also, adjust the valves.  .006 is the correct gap. It is a simple procedure, any V-dub book will help with that.

2) Ensure that the fuel injection hoses are routed properly and not leaking.  Do not replace any of the clamps with the 'ribbed' type ones w/the worm gear.  They chew into the hose and can cause a fuel leak.


Let me know how you make out, and I'm here to help you along the way.

Congratulations on your new VW,  many years of enjoyment with it Paul!


Ron