Fuel Line Replacement - '75-'79 Fuel Injected Bus
By Billy Price, with
suggestions from Jim Thompson and Nick Palmer. Copyright © 2002,
Job: Complete Fuel Line Replacement
Application: Fuel injected Bus 75-79
READ ALL THE WAY THROUGH THIS FIRST
front is front in the engine compartment
|metal fuel lines
Tools and Supplies:
|5 gallon bucket
|Fits under my Bus (barely) to drain the gas.
|For gas leaks
|Pressure gauge, 35 psi
|For testing lines, pump, regulator
|I cleaned the dirt and scum off my rails and they look
|large injector seals
|Spend the money on OEM if you're replacing as the
aftermarket ones are ill-fitting
|small injector seals
|7.5 mm high pressure (35psi) fuel line
|Mercedes-Benz P/N 916030-000527 - try M-B dealership or
European auto repair shop. Or Volkswagen P/N N 020 281 1 from list
vendors like Bus Depot and Vanagain.
|10 mm low pressure fuel line
|I used 5/8". You can also use 1/2" (12mm ID) fuel line or 1/2"
|7.5 mm clamps
|NOT "Gates" style with the exposed screw slots in the band. Get
the ones that have a solid band of metal next to the hose (M-B).
They're a dollar each but worth it. Try a M-B dealer or Euro auto
|10 mm clamps
|I used the old style here as there's only 2 and you get a good
close look at 'em every time you replace the filter.
|Volkswagen 133 133 511, Bosch (long) 0 450 901 005, Bosch
(short) 71013, Wix 33274, or Fram G3743
- Disconnect battery ground strap for fire safety. Make sure the
strap can't fall back against the body and make contact again.
- Drain tank.
If a tank removal/flushing/restoration is in your mind,
now is the time. Why flow old crap into your new
- Remove & replace lines in engine compartment.
Why only engine compartment? I saved the lines to/from
the tank which go through the firewall & under the Bus for last
so I'd only have to go under the Bus once. If you follow the lines
like a map, from tank outlet to tank return, you'll be under there
twice, but this may be more comfortable for some
- Behind #3 (left front of engine) a metal rail comes through the
firewall below the F.I. relays; start here. Follow the combination
metal/rubber lines around the engine to see the scope of your task
as it hits #3, #4, the cold start valve (if you have it), #1, #2,
pressure regulator, through the firewall to tank return.
- Unscrew old clamps. Discard these! If the old lines are hard to
get off, grab a Stanley knife and slit them lengthwise from their
ends on the rails. Expect some fuel leakage.
- Replace each piece as you go. Use each piece of your old fuel
line as it comes off as a template for the new line's length. Make
nice square cuts in the new hose. Sand the crud off the metal rails
as they become available, they're shiny underneath.
- When installing new line, place the clamp fully open on the
hose first. Slip the hose over the flares on the metal lines far
enough so that the clamp can slide over the flare with the hose on
it (tight!) and have plenty of hose to clamp on the far side of the
flare. Rotate your hoses before you tighten so that you can use
their natural bend in a manner that facilitates routing. Sometimes
the hoses are hard to fit, but stay away from lubricants as this is
your fuel system. NO SOAP!
- Got the first piece of rubber on the firewall supply rail?
Good. Don't attach it to the #3/4 injector rail yet because you
should assemble the injectors to the rail first as a sub-assembly.
Don't try this in the engine compartment, it's too tight. I found
getting hose on the injectors themselves to be the most difficult
task. Tight fit, and I had to remove the injectors from their
mounting points to do it. Replace seals if necessary. I reused
- #3/4 rail connected to firewall rail? Now for the cold start
connections. The cold start valve is sorta delicate, so don't
muscle it too hard. It's also one of the more accessible parts of
- Cold start done? Now we get to the #1/2 cylinders where junk is
in the way bigtime. Remove the airbox for working room. I
disconnected my F.I. harness and some vacuum hoses for working
room/routing. Mark everything you take off for later
reinstallation. Be careful here, I knocked the F.I. computer ground
wires off the engine block while doing this and couldn't start my
Bus for three weeks till I found them. Reinstall disconnected
equipment immediately so you don't forget it.
- #1/2 rail remove/replace is typical to #3/4 rail, but in a
- #1/2 rail to pressure regulator, not a bad job.
- That's all for the engine compartment. While here, disconnect
the tank supply/return lines from where they enter the engine
compartment if you haven't already.
- Remove & replace lines under the Bus.
- Remove the return hose coming from the #1/2 side of the engine
to the tank. There are several clips under the Bus that hold the
line. If your old line is hanging down, find the clips so the new
line won't be. This is the longest length of line to replace.
- Finally, the supply from the tank to the engine compartment.
This include the fuel pump and filter, and also has mounting clips
under the Bus. Remove and replace all the rubber and the
- Your fuel path should now be complete. Check ALL the clamps and
connections again. Verify all disconnected equipment is
- With a 7mm box wrench, remove the bolt in the fuel rail between
#3/4. This is where you attach your fuel gauge. I had to cut the
fitting off the gauge I bought and shove the hose on it with a
- Add some gas for a test run. Don't fill up, what if you're
leaking somewhere? I added about 3 gal.
- Reconnect battery ground strap.
- Bus starts? Pressure gauge 28-33psi? No leaks anywhere?
Awesome. No start? Call someone else.
- Shut off the engine and check again for leaks. Remove the
pressure gauge and replace the bolt in #3/4 rail.
- Consider replacing the gas vapor venting system lines, which is
not in the scope of this write-up.
Last updated on Thu Oct 3 17:52:21 EDT 2002