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*rlfrazee
December 11th, 2003, 10:20 AM
#11758: Tachometer doesnt Work Author: rlfrazee, Posted: 12 Oct 2003 12:57 am
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I have a 1994 90 horse 3 cylinder Mariner/Mercury. Went fishing today and the tachometer isnt working. The circuit is pretty simple for the tach. Battery volltage goes to the battery terminal on back of the tach when the key is in the run position. The sense wire or pulse wire if you like comes from the voltage regulator (small non ribbed design) to a terminal block on the motor then to the send terminal on the back of the tachometer. As for a little history the tach worked momentarily when we first started down the lake then it started fluctuating and jumping around finally dropping to 0 rpm. It hasnt worked since. When you turn the key to run before starting the needle does move slightly. Here are some of the things I plan to do. Im going to check for correct voltage at the tach battery terminal with key on or run position. Then Im going to run a jumper from the sense wire at the terminal block on motor to send terminal of tach disconnecting the existing wire on both ends of course. This will allow me to determine if I have a problem in the wire from motor to tachometer. Doing these two things should bring me to either bad tach or bad voltage regulator not pulsing wire. Question, is there a way to determine if the wire is recieving pulses from voltage regulator? If I can verify the wire is getting its voltage pulses then I can be reasonably sure that tach is not counting the pulses and is bad. I do not see any bad connections on any of the pertinent wires that I can visably see. Any ADVICE or other checks I can do before giving up will be appreciated .....RL

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#11777: Author: Wgoodrich, Location: Indiana Posted: 12 Oct 2003 05:01 pm
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Boat tachs are exposed to sun and water a lot. Often times the connections inside the tach will corrode. Sometimes it will be a corroded connection in your fuse block or at the engine.

I suspect you will find a bad tach. My tach went out on my last fishing trip also. I tapped on the tach while running across the lake and it tried to come up but then would die. As long as I continued to tap on the tach it would work somewhat. I suspect you also have a corroded tach.

Not hard to change out and won't hurt near as much as many parts of a boat that must have gold in them. Ha Ha

Let us know what you find.

Good Luck

Wg

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#11779: Author: rlfrazee, Posted: 12 Oct 2003 07:09 pm
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Wg, thanks for the quick reply. Give me a few days to get back to you and the forum. My schedule is pretty full with honey do's tomorrow. But should have time Tuesday to check the tach and will be sure to post what fixes the darn thing. You are right some boat parts have gold in them.....RL

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#11891: Author: rlfrazee, Posted: 15 Oct 2003 02:59 pm
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Wg, I had time today to check out the tachometer. I little history is needed first. About a year ago my stator went bad (one of those parts that has gold in it) Took the boat to a mercury service center the tech installed a new stator that was a replacement upgrade because my original stator was recalled on a service alert bulleton. Not much of a recall though since they make you pay for the new stator plus installation. Anyway had a few other things done and dished out 660 bucks. First day I went to the lake after this my tach wasnt working. When I got home started checking things out and discovered the tech had taken the wires loose on a terminal block where tach, voltage regulator/rectifer, and charging circuit wires from stator all came together and didnt reconnect any of the wires. Noticed where the 2 wires from the charging side of my stator had been arcing against the engine block. Anyway followed my maintenance manual and connected up the wires as shown by manual. Presto my tach worked fine. However wish I had taken it back to tech now to make him aware of his mistake. Shortly after this my starting battery began to become weak and needed recharging several times. Finally took battery in for check and it checked bad. Replaced it. But was suspicious since battery was darn near new. Today I did charging circuit test and discovered I had zero amps in the charging circuit to battery. Now voltage regulator is suspect. Looked closely and noticed what looked like brown gel running down side of engine block directly below voltage regulator, also noticed what looked like melted beads of solder in bottom cowling. Took off voltage regulator. Turned it upside down and it is sealed with that brown gel but can see circuitry. It is fried. Big hole burned in bottom off regulator and visable circuitry is burned up. Now know why tach finally quit working and battery went bad. I wonder now if charging system coming from stator was damaged when its wires were arcing on the side of my engine block due to not being connected properly a year ago. I suppose this could be coincidence and voltage regulator just went bad but I got that deep growl in my stomach feeling ya know. Well a least my motor didnt catch fire as I was traveling down the lake making me into a roman candle. Looks like I get to purchase another piece of boat part gold. Thanks for your help and do you know of an internet site where I can order mercury parts?......RL

Last edited by rlfrazee on 16 Oct 2003 12:11 am; edited 1 time in total

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#11899: Author: Wgoodrich, Location: Indiana Posted: 15 Oct 2003 10:14 pm
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Sure hope not but if that wiring was miswired it may have not only got your voltage regulater but also your whole charging unit. Remember a company such as your marine repair company is only as good as the worst employee they have. You might want to talk to the owner of that repair shop. If he does not back up the mess made at least he will be aware of the employee problem hopefully avoiding another boater experiencing your pain.

Let us know how bad you find it to be. Maybe you will get lucky and only have a bad voltage regulator.

Don't know of a merc parts link on the net.

Good Luck sounds like you could use some.

Wg

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#11906: Author: rlfrazee, Posted: 16 Oct 2003 12:27 am
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Wg, funny you read my mind. Went to the service center where boat was worked on after placing previous post . Talked to manager about the situation and showed all documentation from a year ago. Basicallly just asked if he would consider making things right. He (John) said that he didnt think I could have made up a story like that. He asked me to bring boat to shop they will make all repairs free of charge and check my charging system out and replace anything found to be defective. Also are going to reemberce me for cost of battery or give me a battery, my choice. So looks like things are going better with my luck. I'll let you know what they find....RL

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#11942: Author: Wgoodrich, Location: Indiana Posted: 16 Oct 2003 10:24 pm
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Congrats, sounds like you found an honest business man, seems rare nowdays but still happens. Remember always give a person a chance to make things right before judging.

Good Luck

Wg