Tach problem

pappy3

Seaman
Joined
Jul 31, 2007
Messages
74
When at idle the tach works fine at wot it pegs out or is all over the place! Any ideas? Thanks pappy3
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
When rectifiers start to go, you may see all sorts of erratic tach readings. Start you analysis with that rectifier.
 

pappy3

Seaman
Joined
Jul 31, 2007
Messages
74
Thanks guys! The tach was working fine but I sat the boat up for 4 years and now it has this problem!
emdsapmgr what do I need to do to check it out? What doe the rectifier look like? lol thanks
 
Last edited:

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Thanks guys! The tach was working fine but I sat the boat up for 4 years and now it has this problem!
emdsapmgr what do I need to do to check it out? What doe the rectifier look like? lol thanks

Exactly what motor is it?
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Bill is correct, need to know what year/model you are working on. Early models use a rectifier only. Later ones have a combination rectifier/regulator. Unlikely it's your tach. You can look up your own parts from the factory exploded parts diagrams at this website: epc.brp.com
 

pappy3

Seaman
Joined
Jul 31, 2007
Messages
74
sorry its a 1992 88 spl it doesn't peg out max it goes to zero
 
Last edited:

emdsapmgr

Supreme Mariner
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Dec 9, 2005
Messages
11,551
Your 88 special was a marketing gimmick those years. Actually a 90, but in a cheaper form. Back then the 88's did not have the expensive VRO fuel/oil mixing system, did not have combination rectifier/regulators and power trim may have been a dealer-installed option. Engine ran the same as a 90, but could have been thousands less in initial sell price, but does everything a 90 should. Since yours has a rectifier only, it's a small round device that mounts to the side of the block on the driver's side. HAs 2-3 yellow wires going to it. A fairly inexpensive item. p/n 582399 about $ 35. Since it's considered a cheap fix, most folks just opt to replace it when the tach starts to act up.
 

pappy3

Seaman
Joined
Jul 31, 2007
Messages
74
emdsapmgr I like that answer! lol Beats 100 any day!! thanks pappy3
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Look on the back of tach for the cylinder position switch. Yours should be on 4. Take a small screw driver and rotate it through it's other settings and then back to 4. Then try it again.
 
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