Troubleshooting Tachometer Help

halcrimm

Petty Officer 3rd Class
Joined
Jun 27, 2012
Messages
78
Hey all,

Mercruiser 3.0L Alpha 1 Gen 2 I/O.
S/N OD714746 Engine
S/N OD671270 Transom
S/N OD665768 Drive

Working ever so patiently toward getting first boat in the water. Had the engine running the other day on the muffs (very nicely I might add) but found that the tachometer does not register RPM. I went to the manual to see how to test the tach but all it says is to connect a known good tach and compare the difference. I don't have a 2nd known good tach so I was wondering if there really is a way to test the one that I have. Is there a pick up (sender) of any sort accessible on the engine that I can check for a good signal going to the tach?

Any help would be greatly appreciated.
Hal
 

sptjet90Reflexx

Petty Officer 1st Class
Joined
May 28, 2011
Messages
383
Re: Troubleshooting Tachometer Help

it just reads off the negative from the ignition coil. It could be a bad connection but usually you would have some reading. Its possible the tach is just dead. You can pick one up for as little as 30.00 for a sunpro or something from advance auto.
 

gm280

Supreme Mariner
Joined
Jun 26, 2011
Messages
14,585
Re: Troubleshooting Tachometer Help

Hey all,

Mercruiser 3.0L Alpha 1 Gen 2 I/O.
S/N OD714746 Engine
S/N OD671270 Transom
S/N OD665768 Drive

Working ever so patiently toward getting first boat in the water. Had the engine running the other day on the muffs (very nicely I might add) but found that the tachometer does not register RPM. I went to the manual to see how to test the tach but all it says is to connect a known good tach and compare the difference. I don't have a 2nd known good tach so I was wondering if there really is a way to test the one that I have. Is there a pick up (sender) of any sort accessible on the engine that I can check for a good signal going to the tach?

Any help would be greatly appreciated.
Hal

First you need to verify three things. One is that you have 12 volts going to the tach, you have a good ground, and last you have a proper connection to the engine. If you already verified those three things and you still don't have any readings...it may be time to buy a new tach...
 

halcrimm

Petty Officer 3rd Class
Joined
Jun 27, 2012
Messages
78
Re: Troubleshooting Tachometer Help

I will check thoses things tonight. I do know that when I turn the key I do get needle deflection to the 0 RPM mark.
 
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