Tech Articles

Bosch D-Jetronic fuel injection Vapor Lock Fix

The Bosch D-Jetronic fuel injection that came on the early Volvos were a rather crude but a simple system. The “computer” were basically a spreadsheet but if everything is in good working order, they run well.

The system did have some issues and one problem that occurred on the early injection car was vapor lock. With the injector housings bolted directly to the engine block, it transfers heat in the injectors causing the fuel to turn in to vapor making for hard starts when warm.

Sometime in the early 70’s, Volvo realized something needed to be done and they developed an insulating kit that was part of the later cars.
This was then installed at the factory but also became available as a fix kit for earlier injected cars.

My 1971 1800E had exactly these symptoms. I ordered the kit from and got busy:

I started by removing the complete fuel rail as it is much easier to work on each injector at a time.

Tip: after loosening the clamps, spray a little WD-40 on an L shaped pick. Stick the point between the tube and the rubber hose and move it around. It makes it much easier to put tube and hose apart without damaging the hose. This is important, the short hose coming off the injectors as it is an integral part of the injector.

Remove injector housings with the allen bolt. Also, remove the o-ring in the block as you will need a thicker one.

Volvo calls these fiber washers, another name is phenolic washers.

This is how they go on the injector housing, one washer on each side. This lifts the injector housing a little, hence the reason for thicker o-rings.

Old o-ring (right) and new…yup, on left.

New o-ring in place. If you need to clean this area on the head, have a vacuum next to it as you don’t want any dirt falling in to the engine.

Install in reverse order check for leaks.

As always, if you are not comfortable or qualified to do this work, take it to a shop who can do the job.

Parts needed:

962658 Fiber Washer fuel injection ES/140/164 8ea needed
XXXXXX (part number coming) Thicker 0-ring 4ea needed.

A lot of great Volvo Factory Manuals can be downloaded HERE