Sorry to hear of the problems you have experienced with the MDI boxes on your D2-40. There were early problems with the boxes but I thought these were resolved with generation 3.
Frequently when an MDI box fails it can take the stop solenoid with it. This happens because the stop solenoid is designed for intermittent duty, usually being activated for only a few seconds at a time. But if the MDI box fails, it can energize the stop solenoid continuously, and this causes the stop solenoid to burn out. Even if the solenoid fails, you can run the engine with just a bit of effort. Disconnect the two wire connector and remove the solenoid from the back of the injection pump. If the solenoid has failed in the "stop" position, the small plunger on the solenoid will be extended about 17 -18 mm. Push the plunger back into the body of the solenoid, and replace the solenoid in the pump, but don't plug
in the connector. The engine should now run, but you will have to stop it with the manual stop lever.
The fuel tank
sender is the same for the MDI equipped engine as for the standard engine. The normal metric gage sender values are: 10 ohms when empty and 180 ohms when full. A VP gauge will work with this sender, or you could get a VDO or other gauge as long as it is designed to work with this type sender.
The sender values for a metric oil
pressure sender are the same 10-180 ohms, where 10 ohms is 0 pressure, but as I recall
, the D2-40 is equipped with an oil pressure alarm switch only. There was no gauge sender on the standard engine.
The tachometers on both early non- MDI engines as well as the MDI engines are driven by an inductive pickup which is mounted on the flywheel housing. This pickup contains a magnet and a wire coil and basically counts the number of slots which are machined into the flywheel. Every time a slot moves past the pickup an electric
pulse is sent to the tach (or MDI box) and the tach converts the pulses into an RPM
reading. You will have to remove the pickup from the flywheel housing and count the number of slots which are machined into the flywheel just below the pickup opening. ( I don't remember how many there are)
Mark one of the slots with a magic marker, and then rotate the engine with a wrench on the crankshaft nut. The number of slots will equal the number of pulses per crankshaft revolution, and you will need that number when sourcing a new tach.
Again, you could get a VP tach from the earlier non- MDI D2-40 engine, or a VDO or other brand tach. If you go other brand, be sure you get a tach that can operate on an inductive sender.
I hope this is helpful.