[quote]ORIGINAL: gkamysz

There is no butterfly (throttle) valve in injected diesel engines.

Actually some diesels do use a butterfly throttle.
Basically diesels have 1 of 2 types of govenors in the fuel system, 1/ constant speed,2/ variable speed. things like tractors, generators, dozers and the like have constant speed govenors( yes these can be adjusted in speed too , but they will hold a constant speed irrespective of load), wereas cars/ trucks are fitted with variable speed govenors- basically the spring tension in the govenor is adjustable by a linkage from the accelerator pedal(this type of govenor will allow the speed to vary dependent on the load). Some use a vaccum linkage ie there is a butterfly valve and venturie to create a variable vaccuum which works on a diaphram on the fuel pump to change the govenor settings, Nissan and some Isuzu diesels are some that use this method.
Stewart