Tachometer issue - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**HIGHWAY BY THE SEA** · 09-24-2016, 10:38 AM

I just had my tach rebuilt by a professional gauge repair service and installed it. It worked fine for two weeks, but yesterday that changed. It would work for the first five minutes of drive time, then abruptly go to zero and stay there regardless of what was done to correct it. Turning off the engine for 10 to 20 minutes would allow it to work again until 5 minutes of drive time, then it would go to zero again. What the hell...? It will infuriate me if I have to uninstall this again and resend it back to the repair company. Any ideas on the issue?

*gmachinz* · 09-24-2016, 10:45 AM

Are you running a tach filter w/your HEI?

**HIGHWAY BY THE SEA** · 09-24-2016, 10:55 AM

Quote:

Originally Posted by gmachinz

Are you running a tach filter w/your HEI?

No. I was under the impression that this was not required.

*gmachinz* · 09-24-2016, 11:19 AM

It is recommended to run a filter with any HEI GM style distributor. They were installed on GM trucks beginning in 1975. I know all of the "repro" houses for our trucks don't include them but they should-I do on mine anyway. I don't know for sure if that's your problem but it is one thing I'd be sure to do. Check the circuit board on yours for a overheated capacitor or shorted resistor.

09-24-2016, 10:38 AM	#1
HIGHWAY BY THE SEA Senior Member Join Date: Nov 2012 Location: BY THE CAROLINA SEA Posts: 922	Tachometer issue I just had my tach rebuilt by a professional gauge repair service and installed it. It worked fine for two weeks, but yesterday that changed. It would work for the first five minutes of drive time, then abruptly go to zero and stay there regardless of what was done to correct it. Turning off the engine for 10 to 20 minutes would allow it to work again until 5 minutes of drive time, then it would go to zero again. What the hell...? It will infuriate me if I have to uninstall this again and resend it back to the repair company. Any ideas on the issue? __________________ FRANKENTRUCK 1981 Chevrolet C10 Shortbed Stepside GRANDTRUCK 1968 Chevrolet C10 Stepside Longbed http://67-72chevytrucks.com/vboard/s...d.php?t=584617 PROJECT JIGSAW 1967 GMC C3500 GREAT WHITE 1986 Blazer M1009 454 engine w/700R4 transmission gas conversion

09-24-2016, 10:45 AM	#2
gmachinz Account Suspended Join Date: Jun 2011 Location: Des Moines, IA. Posts: 4,143	Re: Tachometer issue Are you running a tach filter w/your HEI?

09-24-2016, 11:19 AM	#4
gmachinz Account Suspended Join Date: Jun 2011 Location: Des Moines, IA. Posts: 4,143	Re: Tachometer issue It is recommended to run a filter with any HEI GM style distributor. They were installed on GM trucks beginning in 1975. I know all of the "repro" houses for our trucks don't include them but they should-I do on mine anyway. I don't know for sure if that's your problem but it is one thing I'd be sure to do. Check the circuit board on yours for a overheated capacitor or shorted resistor.



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