Here is something that I saved once,
"The FDC is basically a movable stop for the fuel pedal. When you are running a thin fuel, such as gasoline, the stop moves to allow full pedal, and maximum fuel. When you are running a thick fuel, such as WMO, the stop moves to reduce the maximum pedal motion. The idea is the FDC controls the engine so that you get the same maximum horsepower for any fuel.
If you bypass the fuel flow through the FDC, the FDC will act as if it has a very very thin fuel, and will put the stop in the maximum fuel position.... just like it would for gasoline. If you then use some fuel other than gasoline, the injection pump (IP) will be capable of seriously over fueling the engine... lots of black smoke, lots of power, and lots of heat (Can you say meltdown? Sure you can!).
If you are a really disciplined driver, you could bypass the FDC, and drive with diesel fuel, by never going to full pedal... never letting the engine smoke much... I doubt that anyone is that disciplined.
There is a formula method for getting close to the correct fuel adjustment when the FDC is bypassed. That method is to adjust the nut on the compensator stop plate screw (smoke limit) 12 to 16 nut flats (sixths of a turn) clockwise (in the increase fuel direction), and to adjust the droop screw 1 to 2 turns clockwise(in the decrease fuel direction).
[For the stop plate, do not try to turn the threaded shaft. The outer nut is a jamb nut, and the inner nut is the adjustment. Count the nut flats as they pass by until you get to 12... your engine may be happy there, or may need a little more juice, up to 16 nut flats.]
The droop screw adjustment is hard to get at. It is part of the governor's fulcrum and is under the governor cover. It should only exist on the E type injection pumps on the turbo'd engines (I think). When you remove the FDC action, and adjust the smoke limit to compensate, it affects the governor action, requiring the droop re-adjustment for proper idle operation. Most folks that bypass their FDC's skip this step, and sometimes get problems with starting, and idling.
You should get TM9-2910-226-34 from the resources pages of this site before you touch anything!
-Chuck "
And this,
I have found that burning oil actually makes the truck smoke less. So the increase in smoking that you are talking about maybe the diesel that you put in it. I just trying to be courteous and anytime I see someone with their windows down or walking along the side of the road I'll let up of throttle.
