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Bouncing Tach

Old 07-18-2005, 11:14 AM
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Default Bouncing Tach

At higher rpm my tach starts bouncing. It's on the money and steady until about 4500 rpm. When I am trimmed out and running 5000 rpm it's all over the place. I replaced the tach and the new one does the same thing?

Looked for the obvious loose wire and found nothing. Could this be a sign of a bad ground?
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Old 07-18-2005, 11:27 AM
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Default Re: Bouncing Tach

Are you hitting the Rev limiter? My old Checkmate would bounce at wot when it was hitting the limiter?
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Old 07-18-2005, 11:31 AM
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Default Re: Bouncing Tach

Not hitting the limiter, checked it with a tach that clips around a spark plug wire and I was right at 4950-5000 rpm when trimmed out. It starts at about 4500 and gets worse as the rpms increase. Under 4500 it's steady and accurate.
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Old 07-18-2005, 11:32 AM
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Default Re: Bouncing Tach

CHECK THE DIST CAP A BAD CAP WILL CAUSE TACH TO JUMP

JOE
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Old 07-18-2005, 11:33 AM
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Default Re: Bouncing Tach

Okay, now I'm gonna sound stupid but I don't think my motor even has a distributor?

It's a 2003 Volvo Penta 5.7 GXi
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Old 07-18-2005, 11:34 AM
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Default Re: Bouncing Tach

Mine does the same. Merc 575SCi
replaced cap & rotor same problem.

Still looking for a cure too
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Old 07-18-2005, 11:50 AM
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Default Re: Bouncing Tach

Mine was doing that last weekend. Spent about an hour touching every connection and trying to move every wire. I didnt find the loose groung I was looking for but when I ran the boat this weekend it was dead on. one of the plugs on the wiring harness must have been loose.
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Old 07-18-2005, 12:56 PM
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Default Re: Bouncing Tach

same problem on my playboy
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Old 07-18-2005, 01:12 PM
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Default Re: Bouncing Tach

"prongs of the cannonball plug"

you mean the doohicky in the whatcha-ma-thing?

laymans terms please... or ill just tell my boat wrench-a-thingy guy
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Old 07-18-2005, 01:24 PM
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Default Re: Bouncing Tach

I had the problem and the electricals shut my motor down. Ended up re-wiring the port side ignition and something near the distributor
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