I recently purchased a 1993 F250 4wd 5sp. The tack registers sometime while moving, other times it doesn't. I start in 2nd and get to 20 mph the tack starts to register between 1500 and 1700 as I get closer to 25 mph, the tack registers 2000, at which time I shift to 3rd. The tack dies until the speed reaches about 32 mph at which time the tack again comes alive and registers almost 2000. Shifting once more into 4th the same scenario occurs. I need to know if the sensor/sender is bad, but more importantly, where the sensor/sender is located on the motor for this truck. You can respond directly to me at papa1bob@yahoo.com if you choose. Thanks for your help I have a 7.3 turbo pre-powerstroke engine.

 

My bad, completely missed what engine you had. Sorry about that.

 

The tach sender is a common problem on the IDI engines. The tach sender is on the injection pump gear housing, just to the right of the oil filler. It's a large hex head with 2 wires coming from it. The It's common for the wires to get damaged, but if not that, change the sender.

 

Located suspect part from your diagram. Dealer only part for a cost of $103.00. Thanks for your help. If there is a less expensive way to get this part let me know. O'Riley, Auto Zone do not carry it. Thanks again for your help. Sorry so long in getting the thanks back to you.