Guages don't work on Mercruiser 470

[Grizzly6]

I own a 470 Mercruiser, 1980 edition, which I have owned since new. It has 200 hours on it and has served me well. It is stored in a garage year round. Obviously, I only use it several hours a year. When I fired it up this summer, the fuel, trim, oil pressure, battery, tach, temp guages wouldn't work. Bilge pump, and engine compartment vent fan work fine and engine runs fine. What could be the problem?

 

[Bt Doctur]

missing the purple wire to the gauge

 

[Grizzly6]

Purple wire is there and there is power to the guages.

 

[Grizzly6]

The tach needle swings to the right and stays there when I turn the key on. And the other guages don't show anything.

 

[zellerj]

Gauges run through the bayonet (some call it a bullet) connector near the 50 amp circuit breaker on the engine. I would take that apart and shine everything up. To get into the female connectors, use a small wire brush that is used for cleaning the barrels of 22 rifles.

 

[Grizzly6]

Are you referring to the large multi-pin connector?

 

[zellerj]

Yes - I did not know what to call it.

 

[Grizzly6]

Thanks for the advice. Will let you know if it works

 

[nola mike]

If you're getting 12v to all the gauges, next step is to make sure you have a good ground back.

 

[Grizzly6]

Thanks Mike. Will try that, too.

 

[Grizzly6]

Cleaned multi-pin connector (although I don't think it needed cleaning - it looks like new in there) and still no gauges. Will try running a ground wire from the battery to the gauges tomorrow.

 

[wahlejim]

This is screaming bad ground. You have a 38 year old boat with original wires, time to start digging.

 

[wellcraft-classic210]

Does the ground wire go the motor from the gauges // I ask as on the v8s it goes to the motor mount and when its loose or missing the gauges drop out / but the engine will run.

 

[Grizzly6]

Ran a ground wire from battery to gauges ground wire - still no gauges.

 

[Grizzly6]

Ground from battery runs to engine and is secure. Common ground terminal under dash. Gauges grounded to this common terminal.

 

[Grizzly6]

Gauges work!! Thanks for all your advice! Faulty ground near dash cluster. Wires in excellent condition, despite being 38 years old. This rig was built when they still used real wires! All's well! Thanks a million!

 

[Grizzly6]

Gauges work! Thanks for all your advice. Faulty ground near instrument cluster. All's well. Wires in excellent condition despite being 38 years old. Rig was built when they still use real wires.