Tachometer Troubleshooting

[jayhawkokie]

I just purchased a 1987 bass boat with a 1987 90HP Merc. The guy I bought it from said the Tach hasn't worked for several years and he didn't attempt to fix it.

My question is, where do I start trouble shooting the tach and it's wiring to see if it is perhaps a broken wire or bad connector or if I need to purchase a new instrument.

Jayhawkokie
Grand Lake O the Cherokees

 

[Laddies]

Re: Tachometer Troubleshooting

Start by swapping the gray wire on the rectifier to the other yellow post if that don't help check the grey on the back of the tach for voltage, if it's got voltage check the ground and positive connection, if there both good you need a tach.

 

[jayhawkokie]

Re: Tachometer Troubleshooting

Thank You Laddies, I'll check it out

 

[jayhawkokie]

Re: Tachometer Troubleshooting

Ok, here's the skinny. I ran a jumper wire and checked continuity on the Gray and ground wires. I have continuity on the ground, but not on the gray wire.

I've covered the boat back up and won't be able to get back to it for a couple days. Shoule I have had the ignition switch on when I checked continuity on the Gray wire.

I can't imagine why I would have a break in this circuit, everything else on the boat/engine works electrically.

Jayhawkokie

 

[achris]

Re: Tachometer Troubleshooting

There are a couple of plugs in the line that would be worth checking. The first is the connector at the engine. It's a big plug with 10 (I think) pins. Check continuity of the gray from the rectifier to the plug. At the tacho end there should be a harness that plugs into the control box. Check the continuity of the harness. If they both check out, then check it in the main control harness. You may find that what you have is a bad connection in one of the plugs.

HTH,

Chris..........

 

[jayhawkokie]

Re: Tachometer Troubleshooting

On my little bass boat the tach harness doesn't plug into the front of the control panel there is nothing plugged into that terminal.

The main harness from the engine is plugged into another harness in a tunnel behind a panel, behind the controls. I can see the plug with a flash light but it is impossible to get to. The wire harness to the instrument panel splits off from that harness. There is just no way to reach it from either end.

I'm sure my problem is in that plug, but I' not going to disconect a bunch of wires to pulll it out, so I ran a secondary wire to the tach from the rectifier.

Thanks for your input.