Tach not working....

[mrfixit4818]

I have an early 80s v4 115 and I had to re wire the whole boat(thats the way i bought it.anyway the one wire coming out of the engine controller goes to which connection on the tach?there is also a little switch on the back with a 1 -4 setting.currently i ran the 1 wire from the controller to the s nut and the ground was already connected to the housing and it does not work currently,can i ck. the tach itself with an ohm meter?any help would help,btw I ran it for over 3hs straight today and it was great.the guages are in bad shape but the tach and trim are broke,speedo and gas are good.

 

[psteurer]

Re: Tach not working....

I looked up your motor and the cross reference table I have says you should set the dial on the back to 6P. Re-check the back and see if you can find the 6P.

I am not clear on the rest of your post. But here are the wire colors. Black is the ground. Purple is the ignition (so when you turn the key off the tach is off). Gray is the send wire. On most tachs, the wire posts on the back of the tach are labeled as to what they are (i.e, IGN, GRD, SEND). You might have another wire for the light (usually blue and the wire post is at the top of the tach.

It is very easy to do this if you buy a tach wire harness. There is a 3-wire plug connection on the remote control. The connection is right below the ignition switch and sometime protected by a rubber cap. But you can definitely hardwire the tach into the remote control if you want to save the $40 or so for the tach wire harness. To see a tach wire harness type in OMC Tachometer Wire Harness in a search engine. They might have one for sale here on iBoats.

 

[ezeke]

Re: Tach not working....

It's important to use the plug on the standard remote correctly. Often a single wire is connected there to the positive accessory terminal for other than the tachometer signal.

The gray wire is the signal wire for the tachometer and it is connected to the rectifier at the engine. Any voltage riding that gray wire will instantly destroy your rectifier.

See: http://www.maxrules.com/graphics/omc_pics/REMCONTBOX.jpg

 

[mrfixit4818]

Re: Tach not working....

The rubber plug on my controller has the gray(center prong wire out only)its dark out now but in the a.m. i will pull the tach out and see how many connections are on my tach,i only noticed 2 (s and grd)but maybey there is more,should there be 3?

 

[jonesg]

Re: Tach not working....

pos. neg and signal.
sometimes 4 ,...for a guage light bulb.

 

[psteurer]

Re: Tach not working....

I would suspect what the previous owner did was wire the positive and negative leads directly to the pos and neg accessory busboards (if you had those) usually located under the dash. The previous owner did not use the positive and negative leads that were in the plug on the controller, likely to safe the $30-40 that it would cost to buy a tach harness.

I recall there were some very old tachs (50's-60s' vintage) that had two wires. If you have one of those, you might want to consider replacing it.

 

[mrfixit4818]

Re: Tach not working....

Took the tach out again this morning and there is only 2 stud connections on the back of it,s and ground,also there is a little dial adjustment with a small flatblade screwdriver 1 - 4 ,it is (was)on 1 ,the plug has one wire coming from the control unit and it is the center (gray)connection of the 3 prongs.The guy i bought it from said everything worked.Im stumped how this tach got its power??????The tach signal is not any type of power and i was warned to never put power on it.

 

[mrfixit4818]

Re: Tach not working....

I would suspect what the previous owner did was wire the positive and negative leads directly to the pos and neg accessory busboards (if you had those) usually located under the dash. The previous owner did not use the positive and negative leads that were in the plug on the controller, likely to safe the $30-40 that it would cost to buy a tach harness.

I recall there were some very old tachs (50's-60s' vintage) that had two wires. If you have one of those, you might want to consider replacing it.

The tach has a date stamped oct 1979

 

[psteurer]

Re: Tach not working....

I did not think that 2-wire tachs would work on your motor. But maybe they would. I would suggest that you make sure your connections for both ends of the two wires are clean. Remove the gray wire from the control box connector, clean it and then plug it back. For the two posts on the tach, make sure those are clean. And for the ground wire, make sure it is going to the ground busbar and it is clean too. If that does not work, I would suggest you get another tach. Sometimes eBay has used OMC tachs with the wiring harness already connected.

 

[mrfixit4818]

Re: Tach not working....

won these on fleabay,http://cgi.ebay.com:80/ebaymotors/w...50372929719&ssPageName=ADME:X:RTQ:MOTORS:1123 does anyone know how many pole alt. is on a early 80s johnson 115 v4

 

[psteurer]

Re: Tach not working....

According to my chart from Teleflex, all OMC V Models have 12 poles. So Teleflex says to set the dial on the back of the tachometer to 6P.

 

[mrfixit4818]

Re: Tach not working....

Cool caint wait to get my new guages,they look cool,not sure if its going to include instructions or not but it looks pretty simple.is there a backup battery for the hour meter?is it resetable?

 

[mrfixit4818]

Re: Tach not working....

According to my chart from Teleflex, all OMC V Models have 12 poles. So Teleflex says to set the dial on the back of the tachometer to 6P.

Installed them today ,doesnt the 6 mean 6 cyl.on the back of this tach? there is a 4 cylinder switch 2p,havent started it yet it got dark on me ,but the writing on the back says the no. is the amount of cylinders,did not get directions with these purchased from ebay.went to the teleflex website but could not find the instructions,they are the sterling model with the hour meter built in.also my tilt is reading backwards....

 

[SparkieBoat]

Re: Tach not working....

do you have your tilt gauge in upside down..lol..just joking..maybe wires are reversed..I would think the setting for the tach would be for the 4 cylinder. it should be reading around 900 at idle.

 

[mrfixit4818]

Re: Tach not working....

do you have your tilt gauge in upside down..lol..just joking..maybe wires are reversed..I would think the setting for the tach would be for the 4 cylinder. it should be reading around 900 at idle.

The only thing i can reverse is the wires from the sender to the s terminal.but I dont think thats going to change the ohms reading to ground.

 

[skippy2235]

Re: Tach not working....

From what I have read here, cause I will have the same issue in about a month as you.
to find the pole selection value:
number of magneto poles, in this case 12
divide the number of cylinders, I think you said 4
12 / 4 = 3
I would try 3 pole and see what the reading is.

 

[psteurer]

Re: Tach not working....

For the question on the tach, the settable switch is always a source of confusion. According to my understanding, the numbers with C appended after them (E.g., 4C, 6C, 8C) are for 4 stroke motors. For these applications you set the dial to the number of cylinders. The numbers with P appended (e.g., 2P, 3p, 4P, 5P, 6P) are for 2 stroke moters. For these applications you set the dial to 1/2 of the number of alternator poles. For your V4 OMC motor, there are 12 alternator poles so the correct setting is 6P. It is not 6C

 

[mrfixit4818]

Re: Tach not working....

According to my chart from Teleflex, all OMC V Models have 12 poles. So Teleflex says to set the dial on the back of the tachometer to 6P.

6p was right,at first i had it on 4cy and it read 3000 at idle,6p reads about 1000 at idle,I did need to put a rectifier in. The aluminum silver sterling gauges look great,The only problem is that the trim is for a mercury.how hard is it to take a teleflex gauges apart,was thinking of buying a same size teleflex trim for a johnson and try to switch the electronics or the screen inside because they didnt make sterling for johnson. has anyone ever done this.Nevermind found my gauge at boatfix.com for omc,put my mercury gauge on fleabay starting bid $10

 

[mrfixit4818]

Re: Tach not working....

Well all is great now,recieved and installed the matching teleflex trim .had to tweek the sensor by the motor now it is exactly on dn when it stops,also replaced the fuel lines and primer bulb n filter(on sale at wally world)new marine battery,floor,carpet and seats too.runs exc.Not bad for a 1982..go johnson ....Had it out sat.Thanks everone for all the great info.....