I am restoring an 86 with a 6.9. My tach is all over the place and below zero at idle. How can I trouble shoot thiss issue? Also does anyone know of an aftermarket tach and sender that will work. I am considering doing away with the entire stock instrument cluster and fabricating a costom panel from scratch. Any insight or a good vendor for the guages and senders would be great.

 

yers prolly reads from the cam sensor????

go to this joint

Tiny-Tach: Diesel Tachometers

they sell one that has a transducer that bolts to any injector line to read the pulses.........................easy man

 

If the 6.9 is the same as the 7.3 idi, then it picks it up from the injector pump timing gear right on top.