ChesterChop Posted October 23, 2021 Share Posted October 23, 2021 I have a 1987 E9 400 and the tach quit working. Mine connects on top of the motor. I disconnected the cable. The cable is a male end with a key molded into it. It slides into a shaft with a notch for the key. Should the shaft spin when the engine is running? Quote Link to comment https://www.bigmacktrucks.com/topic/68551-tachometer-not-working/ Share on other sites More sharing options...
Joey Mack Posted October 23, 2021 Share Posted October 23, 2021 the saft in the injection pump turns when running.. chuck up the cable in a wimpy cordless drill and spin it to see if the gauge works. go slow and have someone watching the gauge... I think you have to put the drill in reverse.. just go slow when figuring which direction is correct. when you get that figured out, then run the drill up and it helps to know the top speed of the drill so you can sort-a get an idea that the tach is reading good... not a cure just a test.. Jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/68551-tachometer-not-working/#findComment-481729 Share on other sites More sharing options...
ChesterChop Posted October 23, 2021 Author Share Posted October 23, 2021 I'll try that. I had it unhooked and started up the truck. The shaft in the pump wasn't turning. Quote Link to comment https://www.bigmacktrucks.com/topic/68551-tachometer-not-working/#findComment-481730 Share on other sites More sharing options...
Brian L Blaylock Posted October 23, 2021 Share Posted October 23, 2021 If the shaft in the pump isn’t turning then there’s something wrong with your tach drive and it needs either repaired or replaced 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/68551-tachometer-not-working/#findComment-481731 Share on other sites More sharing options...
ChesterChop Posted October 23, 2021 Author Share Posted October 23, 2021 Thanks. Could the tach drive have another name? I'm not finding anything when I search it. Quote Link to comment https://www.bigmacktrucks.com/topic/68551-tachometer-not-working/#findComment-481742 Share on other sites More sharing options...
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