Return Line Kit:
To be clear, the return lines return a small amount of fuel that was not injected into the cylinder when the plunger opened and closed the needle. It comes back up through a tiny passageway in the injector and back out through an opening between thet is midway between two rubber o-rings in grooves on the outside of the injector. These O-rings seal the black return line caps that are pushed down over the injector and the fuel travels through those caps and rubber hoses back to the fuel tank. When the o-rings get old they lose elasticity, tend to get a flat on the side where they seal to the cap and then leak. They can leak downward onto the large hex of the injectors and into the injector recess areas or upward to the top of the black caps.

Another place to definitely look for a fuel leak is on the high pressure line fittings on the back of the Injection Pump and the Center one which is the steel feed line from the fuel filter assembly. THAT one was loose and leaking on mine and it's virtually impossible to see a leak there. I was able to get my long thin fingers down in there and I thought I felt it but what I did to confirm it was stuff a paper towel down into that area. I had to tighten it up close to a quarter of a turn.

1) Remove the air cleaner assembly for necessary access.

DON'T FORGET: Before disconnecting the steel lines remove the 4 steel clamps (2 on each side) that hold the injector lines together at a specific spacing. Each clamp has 2 bolts and a rubber insulator against the lines. The purpose of the clamps is to prevent excessive vibration which can eventually crack the steel lines or cause leaks at the line fittings. Otherwise you'll probably bend the lines when trying to get the return caps on - (to be avoided!). Don't forget to reinstall them after you have tightened down the fuel injector lines.

The length of rubber fuel line between the caps should be exactly 4 inches (no more) or very slightly less is fine- this way they will all be in a straight line and not dip downward. You can pre-cut these and pre-assemble the 4 caps, fuel hose and clamps and install all four at once (the easy way).

This is the installation sequence I would use:

1) I would measure the old line that crosses over behind the intake from back cap on the passenger side to the fitting on the steel return line tube which comes from the top of the injector pump back along the driver's side of the intake to a compression fitting at the back. Below that compression fitting is where that rubber fuel line is clamped and it's easiest to access if you clamp the return hose on that one first. Route the hose back to the passenger side and clamp it to your new black end cap on the passenger side.

2) Disconnect that same steel line compression fitting at the back driver's side and then loosen the compression nut that connects that steel line to the top of the Injection Pump so you can move it enough to install the new "olive' shaped gasket on the back end of that steel line. It's an important seal and easiest to do that now before installing the driver's side return line caps. Tighten the compression fittings - not too tight - and use a flare wrench for tubing connectors (if you have one) to be safe. The Brass compression nuts can easily crack if over tightened.

The rest of the job is EASY. Put a light touch of oil on the O-rings and olive seals after they are on is fine.

The other 'olive' style seal goes on the steel injection pump feed line where it connects to the fuel filter head. That compression fitting is brass so do not over tighten it! It doesn't take much torque at all to provide a very good seal.

The copper washers in the kit are used in the fuel injector seats if you are replacing the injectors.

 

Test lights and Continuity testing are a waste of time ...

The only way to test the harness is to do a Drop Test ... Nothing else will work!

One strand of copper is continuity, one strand of copper can carry 12v, BUT one strand of copper CANNOT carry the AMPs!

A typical properly done drop test will show ~3 volts less than the battery voltage at each Glow Plug, That's normal, it is designed that way, small wires, resistors etc ...

On the flip side, Voltage testing between ground and each Glow Plug connector while hooked up and Glow Plugs ON, should be ~9 volts on a good system, NOT less then 7.
But this can fail to correctly diagnose a bad system!

-Enjoy
fh : )_~