Tachometer going crazy

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ScottSVogel
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Tachometer going crazy

Post by ScottSVogel » Tue Oct 15, 2019 9:41 pm

Hi, when my Pinz 710 is idling everything is fine, but at higher rpm's the tach goes crazy, bounces back and forth and shows readings that are much too high. Is there a resistor or something I can put in line to obtain normal readings?

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rmel
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Re: Tachometer going crazy

Post by rmel » Tue Oct 15, 2019 11:10 pm

Need a wee bit more information to help ...

Did your Tach work properly before and recently went bonkers?

What model Tach are you using and what are you using as a source
for a RPM pulse, I presume the distributor ground switched terminal?
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q

ScottSVogel
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Re: Tachometer going crazy

Post by ScottSVogel » Wed Oct 16, 2019 1:32 pm

When I first bought this rig, the tachometer was all over the place. Then, after it was serviced a few years later, the tach worked great. More recently, I had some electrical problems where coils were being destroyed. After this problem was fixed, the tach was a mess again.

I have a VDO tach.

Unfortunately, I'm not sure by your questions surrounding "what are you using as a source
for a RPM pulse, I presume the distributor ground switched terminal?"

Can you elaborate?

Regards, Scott

Texas710
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Re: Tachometer going crazy

Post by Texas710 » Wed Oct 16, 2019 1:33 pm

I had this issue and it was right before my RPM limiter failed. I did a write up about it, search "VDO Tach jumping around". Took the RPM limiter out of the loop and have not had the issue return.

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