I'm starting work on my recently purchased 1979 D-100 318 automatic. The previous owner had mickey-moused numerous add-ons including a badly fitted Sun brand tachometer.

After I disconnected this tach, now the truck will not start. Engine turns over fine, but it won't fire. I'm sure the tach was getting signal from somewhere for the rpms, so any hints on where to begin looking for my problem?

I don't have a wiring diagram for the tach or for the truck. Chilton Manual is on order, just not here yet.

Thanks in advance for any help!!!

 

mabe you should try reconnecting the tach. i would have to guess you are not geting spark.

 

Not going to stick the tach back in there, so I guess I'll backtrack all the spaghetti wiring the previous owner put in there. He added the tach, a head unit, and jury-rigged a horn button, and managed to add about 20 miles of crappy wire taped and zip-tied in various places. I'm sure i'll find somewhere that he pulled rpms from, and find the interruption in the current.

Yeah, I know I'm not getting spark, just hoped someone had experience with where the tach got signal from, so I would know where to look.

 

you could try testing for power at the ballast. if there is no power there then you could run power to the ballast to get your truck running if you need to move it.

 

If I remember correctly all the after market tachs I ever installed got the signal from the negative side of the coil.