Tach reading wrong then right????

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fishingman220

Chief Petty Officer
Joined
Jun 13, 2008
Messages
568
This weekend when i left the dock, i took off and when trying to get on plane, i looked at the tach and it read 6200. i know that wasnt right, and once on plane i took alittle closer look at it and it went back to working where it normally is, around 4200. is there a way to fix this, and also is there a way to check it to see if it is readin correctly?? its is a mercruiser 5.7 with thunderboltIV
 
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wiretwister

Seaman Apprentice
Joined
Apr 26, 2009
Messages
34
Re: Tach reading wrong then right????

Could be your rectifier on its way out..........

Wire
 
F

Fl_Richard

Lieutenant
Joined
Jan 21, 2005
Messages
1,428
Re: Tach reading wrong then right????

Spin the pole selector on the back of the tach a few times. Often a little corrosion builds in there and spinning the selector wipes it clean. Fixed two of my tachs this way (OMC Brand).

Just ensure you return it to the same position when your done.
 
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wiretwister

Seaman Apprentice
Joined
Apr 26, 2009
Messages
34
Re: Tach reading wrong then right????

I will give that a try myself.......My tach is whacked out too.

Wire
 
P 0 P E Y E

P 0 P E Y E

Chief Petty Officer
Joined
Jun 3, 2009
Messages
441
Re: Tach reading wrong then right????

Could the tach be right and the prop, hub or donut be slipping?
 
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Fl_Richard

Lieutenant
Joined
Jan 21, 2005
Messages
1,428
Re: Tach reading wrong then right????

If when the tach is jumping the engine rev's at the same time sure, any of those is possible.
 
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wiretwister

Seaman Apprentice
Joined
Apr 26, 2009
Messages
34
Re: Tach reading wrong then right????

I know for sure my tach is whacking out......jumps to 8000 then back to 3000-4000 or whatever it feels like doing.

wire
 
F

fishingman220

Chief Petty Officer
Joined
Jun 13, 2008
Messages
568
Re: Tach reading wrong then right????

i know the motor didnt spin up that fast, it sounded the say as everyother time and it never goes over 42-4800
 
W

wiretwister

Seaman Apprentice
Joined
Apr 26, 2009
Messages
34
Re: Tach reading wrong then right????

Sorry....I was thinking of a rude.........live it up !!
 
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