After installing aftermarket tach the truck will not start

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mattheww2152

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Hey I’m new to the website and I’m not 100% sure if this is the right place to post this but in my 1986 k10 I wanted to add a aftermarket tach so I installed it and hooked it up to the tach port in the hei but it will not start. I have unplugged the tach from the hei and the truck runs. I relooked over the instructions and looked all over trying to find out why it’s doing what it is but, I haven’t found anything about the problem I’m facing. Any ideas?
-Matt
 
PrairieDrifter

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Did you wire the tach correctly?
 
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mattheww2152

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I believe so I’m going to double check again but I just hadn’t been able to find anyone talking about a no start issue after installing one
 
PrairieDrifter

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mattheww2152 said:
I believe so I’m going to double check again but I just hadn’t been able to find anyone talking about a no start issue after installing one
Click to expand...
Wiring can do weird crap if not hooked up correctly. Or in proper working order.

What brand tach?
 
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mattheww2152

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It’s a equus tach I might mess with the ground and see if that does anything I’m just confused with it preventing it from starting
 
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andybflo

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mattheww2152 said:
It’s a equus tach I might mess with the ground and see if that does anything I’m just confused with it preventing it from starting
Click to expand...

I'm assuming you used the tach output on the HEI? The wire that's next to the switched ignition power source for your spark? Check there...

I'd bet you jiggled that wire loose, or you have a dead short, somewhere on the tach signal input wire, drawing current off the HEI.

Unplug the tach lead. re-seat the HEI power. Try to start truck. If it starts, re-add tach lead. You'll chase it out that way.
 
75gmck25

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I speak from experience - if that tach lead connected to the HEI is grounded, it stops the engine from starting. In my case ( on a Ford E150) I had run the tach wire too close to the clutch linkage and a worn spot on the wire grounded on the linkage. I could push down the clutch and the engine would die.
 
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mattheww2152

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I did a little more wiring and just added a whole new ground to the truck and it seems to work so thanks for the idea guys
 
PrairieDrifter

PrairieDrifter

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mattheww2152 said:
I did a little more wiring and just added a whole new ground to the truck and it seems to work so thanks for the idea guys
Click to expand...
New tach ground?
 
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