Bosch VW Diesel Injection Pump Info


Date: 3/09/2003

This information is from Bosch publication "Diesel Fuel Injection"
first edition published June 1994. ISBN 1-56091-542-0.

This book is out of print and finding a copy can be very difficult.
These pages show the VE pump as used on VW 4 cylinder engines. Adjusting the Full Load Adjustment Screw will alter the amount of fuel injected into a cylinder when the pump is at full throttle.

Screwing the screw into the pump will increase the injection amount. Do not turn the screw more than about 1/4 turn at a time, the adjustment is very sensitive.

Injection starts at the point determined by pump timing. A constant amount of fuel is injected per degree of engine rotation, so increasing the full load injection amount will lengthen the period of fuel injection. Particularily with a turbo engine, be carefull of major increases in full load injection amount without also having installed an exhaust gas temperature gauge. It is possible to increase the injection amount (lengthen the period of injection) such that the fuel is still burning when the exhaust valve opens. If this happens, you will see a major increase in full load exhaust gas temperature - which is not desirable. I have used 1100F as a temperature redline measured after the turbo.

If you see a 300 or 400 degree increase in full load exhaust gas temperature after the last load screw adjustment, add some more timing advance to the pump adjustment. This will cause injection to start earlier, and thus will cause end-of-injection to be earlier and thus the burning of fuel to be finished before the exhaust valve opens. You will have to play with this when you are at this point. if you still see the high full load temperatures, again try more advance or a little less on the full load fuel screw.
 


The fuel adjustment screw is called the Full Load Adjustment Screw. It is shown immediately over the electronic shutoff valve [ area #4 ].




The Full Load Adjustment Screw is shown clearly here.
It is immediately over the eletronic shutoff valve #8.





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