taken from http://www.members.shaw.ca/k2pilot/
Lots of guys have at one time or another wanted to know how to adjust their Stanadyne DB2 fuel injection pump on an idi 6.9 or 7.3 diesel engine. It isn't really difficult to do, but I recommend not messing with the stock setting unless you have a pyrometer. It doesn't take much to overfuel a stock naturally aspirated engine, often with disastrous results.
Safety as always is important. On that note, probably the first thing one should do would be to disconnect the batteries, to ensure there is no power to the pump, or at least remove the wires so that if/when you rotate the engine, it will not start. The adjustment screw lives within the pump, but can be accessed through a little door on the passenger side of the pump. It is triangular in shape, and is held in place with 2 small bolts, and a gasket underneath to seal it. It looks like this
.You will want to have either a shallow dish or a bunch of rags under the pump when you remove the plate, as about a pint of diesel fuel will spill when the plate comes off. The next thing to do is to turn the engine to align the adjustment screw internally. This can be done one of two ways that I know of. 1. You must put a large socket (15/16'ths) on the bolt on the front of the crank pulley. Rotate the engine till the timing mark on the vibration damper is at about the 1 o'clock position as seen from the front of the engine. This should line up the insides of the pump so that the adjustment screw will appear in the opening behind where the cover plate was on the pump. Since the crank turns twice for each one rotation of the injection pump however, you may get the timing mark to the 1 o'clock position and still not be able to see the adjustment screw inside the pump. It would look like this. (A small dental type mirror may help to see inside the pump here because of the angles etc)... If you look in and cannot see the adjustment allen screw
, you must rotate the engine 360 deg. or one full rotation clockwise, till the mark again lines up at about the 1 o'clock position, and then you should be able to see the screw, and it should look like this
. The other way to align the pump, is to take the cover off of the front of the injection pump cover housing. Inside this is the bolts that hold the injection pump timing gear onto the pump. There is also an alignment dowel. If you rotate the engine till this alignment dowel is at exactly the 12 o'clock position, then the adjustment screw will be visible through the opening behind the cover plate. Here's a pic of the opening and the dowel, but with the gear-to-pump bolts removed, and the dowel is at the 4 o'clock
position instead of the 12 o'clock. Ok, now, all that is required is to get a good quality allen wrench which fits the adjustment screw(5/32) in size. The adjustment screw has locking threads, so make sure you have a good wrench, 'cause you don't want to damage this one or drop little bits of metal shavings inside your pump. To increase the fuel setting, it is generally recommended to go in small increments. Usually 60 deg. rotation, which is about the same as turning the wrench one flat, or 1/6'th of a turn. Clockwise will increase the fuel setting, counterclockwise will decrease the fuel setting. Put the cover plate back on, being careful not to overtighten the little bolts, replace the wires on the pump, and go for a run to see how it goes. Don't forget to watch that pyrometer!! Good luck with it.