My 83 F-250 5.8 has been sporadically missing and sometimes completely dying for no apparent reason (with a loud backfire in the exhaust following the shutdown). I have already replaced the ignition control module and the coil (as well as the wires and connectors on the coil), but it did it to me again this morning. I was only going 10 mph and the truck died, backfired, and then went back to running fine again.

Question: Could a bad tachometer cause this sort of erratic behaviour? I had this same tach wired up in my 88' Dodge Ramcharger before putting it in this truck and I had the same problem with it a few times, but I always figured it was a bad sensor or something since it was fuel injected. The tach always seems to work and even when the truck does die completely and won't start the tach still shows RPM's while you are cranking. Can anyone provide some insight on what may be going on? Thanks in advance for your help!!

 

Any and all ideas are welcome!

 

Sounds like the timing advance on the distributor.

 

Well, after cutting the tach wire to my coil I have determined that my tach was INDEED causing all my ignition problems. I have been driving the truck for a week without so much as a single problem now. I don't know exactly what happened to the tach or what caused it to go bad, but the truck is running fine now If only I would have figured this out when the tach was hooked up to my Ramcharger I could have saved myself a LOT of frustration and money. Oh well! At least now I know...

 

a cheap tach may not like the 'direct from the coil' output a ford uses. better to go
indirect by using an MSD box as an isolator if your coil terminal output fried the tach.

 

Could be an old design tach, meant for points/condenser ignition.