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-   Do It Yourself, Boating on a Budget (https://www.offshoreonly.com/forums/do-yourself-boating-budget-249/)
-   -   Tach goes iradic after 4K (https://www.offshoreonly.com/forums/do-yourself-boating-budget/259289-tach-goes-iradic-after-4k.html)

Thunderstruck27 08-01-2011 11:56 AM
Tach goes iradic after 4K
 
I put a new dash and livorsi gauges in the fever this spring. The tach works fine from 0-4K. Once I get past 4K it starts jumping around between 0 and 2K. The engine (carb-502) is running strong so it has to be an electronic problem. Any ideas on what to look for will be appreciated...:hitit: has been tried and doesn't work.LOL
Thanks!:drink::drink::drink:

David Stotz 08-01-2011 12:14 PM
What ignition system are you using?

Thunderstruck27 08-01-2011 01:10 PM
1 Attachment(s)
Originally Posted by David Stotz (Post 3466840)
What ignition system are you using?
Thunderbolt...

Thunderstruck27 08-01-2011 08:04 PM
ttt

firehawkcat 08-01-2011 08:06 PM
All tachs work on 4,6,8 cylinders. make sure you are on the 8 cylinder should be a button or switch on back of tach

blue thunder 08-01-2011 08:14 PM
I see the problem. Your negative (tach) wire that goes to the coil is too close to the coil primary wire and/or plug wires.

Thunderstruck27 08-02-2011 09:24 AM
Good eyes
 
Originally Posted by blue thunder (Post 3467355)
I see the problem. Your negative (tach) wire that goes to the coil is too close to the coil primary wire and/or plug wires.
BT...you've got some good eyes! I'll move it this weekend to see what happens. THANKS!

David Stotz 08-04-2011 08:02 PM
TS27,
Sorry I didn't get back sooner. The reason I asked about ignitions is I chased the same demons with an MSD set-up. I thought the factory guys were giving me a line when they told me the tach trigger wire was being affected by the high energy output of the ignition system. They said to make sure the trigger wire was well isolated. After trying everything I thought would solve it I took their advice. THEY WERE RIGHT! Sounds like you have a similar problem.
Dave

Thunderstruck27 08-05-2011 06:59 AM
Originally Posted by David Stotz (Post 3470321)
TS27,
Sorry I didn't get back sooner. The reason I asked about ignitions is I chased the same demons with an MSD set-up. I thought the factory guys were giving me a line when they told me the tach trigger wire was being affected by the high energy output of the ignition system. They said to make sure the trigger wire was well isolated. After trying everything I thought would solve it I took their advice. THEY WERE RIGHT! Sounds like you have a similar problem.
Dave
DS...I'll be checking/correcting that tonight when I get to the lake!...thanks.:drink::drink::drink:

GAUGETHIS 08-06-2011 08:03 AM
Tach
 
Thunderstruck is exacly correct. It is a loose wire to the negative side of the Coil ground or bad/ loose spark plug wires. Also check the ground on the coil. It gets its ground from a bracket and if the bracket is not grounded hence the iratic signal. Hope this helps Good luck


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