tach problems

Terry G.

Seaman Apprentice
Joined
Oct 6, 2001
Messages
37
Greetings,<br /><br />I purchased a 1983, 50 HP, 4 cylinder Mercury. I decided to install a tach. I purchased a Teleflex tach off E-Bay. It was new and still in the package, never opened. Went to my Mercury dealer and purchased a wiring harness that goes into the remote box. I hooked the tack up per Mercury instructions (purple to ig, gray to sending and black to ground). I set the dial switch to 6P per Teleflex instructions.<br /><br />Went to water and it showed 4000 RPMs. WOT should be 5000-5500. My prop was a 14 pitch. I decided to move to a 12 pitch in order to bring RPMs up as well as get better hole shot. Installed prop and she came out of the water but the RPMs is still at 4000 WOT. I checked the connections and re-read the instructions about the dial settings. 6P is where it should be.<br /><br />I have a Sears Engine Analyzer I use to work on my old truck and my old Mercruiser. It checks RPMs, Dwell. amps, volts, etc. Can I use it on an outboard to check to see if my new tach is bad? The way I use it on my truck is to hook the cables to the battery and a lead to the coil and one to the alternator. What else could be wrong so the tach does not go above 4000 RPMs?<br /><br />Thanks,<br /><br />Terry G.
 

Trent

Captain
Joined
Nov 17, 2001
Messages
3,333
Re: tach problems

Sorry your engine analizer will not work. Check this link out to see if it might help you?? web page
 

Terry G.

Seaman Apprentice
Joined
Oct 6, 2001
Messages
37
Re: tach problems

I e-mailedTeleflex and this was the reply:<br /><br />HELLO AGAIN TERRY,<br />I'VE GONE OVER DATA GIVEN US BY MERCURY MARINE AND IT SAYS 45 HP THRU V6'S HAVE A 12 POLE ALTERNATOR WITH 6 PULSES PER REVOLUTION (6P). HOWEVER THEY DO NOT SPECIFY MODEL YEAR. SUGGESTION WOULD BE TO HAVE A SHOP MECHANIC TEST THE ACTUAL RPM FOR YOU. BY ROTATING THE SWITCH TO 5P, 4P ETC., WILL INCREASE THE READING. ALTHOUGH MERCURY SAYS 6P, YOU MAY HAVE TO ADJUST THAT SETTING TO MATCH THE MECHANICS RESULTS. MERCURY'S CUSTOMER SERVICE # IS 920/929-2323.<br /><br />Do you guys think this is the way to go?<br /><br />tg
 

Terry G.

Seaman Apprentice
Joined
Oct 6, 2001
Messages
37
Re: tach problems

Thanks Trent.<br /><br />I wish I could get some more advise on this matter.<br /><br />tg
 

petryshyn

Commander
Joined
Oct 3, 2001
Messages
2,851
Re: tach problems

Terry<br /><br />You're going to have to borrow a mechanical tach for the end of the crankshaft, or optical/strobe tach to check the accuracy of your electronic tach. There is no better way.....
 

Terry G.

Seaman Apprentice
Joined
Oct 6, 2001
Messages
37
Re: tach problems

Thanks Mr. Schematic.<br /><br />I really appreciate your input, and I learn so much from your posts. I'll track down what I need and get started. <br /><br />Take care.<br /><br />TG
 

rdmcphe

Cadet
Joined
Jan 11, 2002
Messages
17
Re: tach problems

I have a '81 Mercury 50 HP 4-cyl. I recently installed a new Quicksilver tach. I set it to 6P as per the instructions and it works fine. The motor idles around 700 RPM. It revs at 5400 RPM at W0T with a 14 pitch propeller on a 15.5' fiberglass boat. What size/weight of boat do you have?<br /><br />Here's a link to a page on Mercury parts site with tachometer settings...<br /><br /> http://www.mercurypartsexpress.com/...9&chart=34&key=4170&level=3&store=Accessories <br /><br />The line "Mercury/Mariner (2-stroke) 45 thru V-6 (U.S. Origin)" is the one that applies.<br /><br />I hope this helps.<br /><br />Regards,<br />Russell
 

BBogey

Petty Officer 2nd Class
Joined
Aug 4, 2001
Messages
140
Re: tach problems

I too added a tach, and while it seems to work great, I have a question...<br /><br />When I turn the motor off, sometimes the needle will creep up to around 1,000 RPM's, this is AFTER the motor has been turned off? AS soon as I turn the key one click (NOT all the way on) the needle comes back to ZERO?<br /><br />Is this normal?<br /><br />THANKS!
 

petryshyn

Commander
Joined
Oct 3, 2001
Messages
2,851
Re: tach problems

BBogey <br /><br />Because of your meter movement style (balancing coil) it is normal not to remain on zero. It should zero when key turned on.....
 

BBogey

Petty Officer 2nd Class
Joined
Aug 4, 2001
Messages
140
Re: tach problems

Thanks very much, you've given this rookie boater one less thing to worry about! :cool:
 
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