Merc. I/O gauges

[rjg41]

1994 Alpha Merc. I/O bought recently bought used. Hardly used. Freshwater only. Clean.<br /><br />All is well except oil pressure and temp. gauges work intermittenly. Engine works fine and no alarms. Have checked connections on the gauges and the sensors I can find on the engine. The limited manuals I have seem to suggest that there are separate sensors for the alarm system and the gauges but I cannot find a second one for either.

 

[Bondo]

Re: Merc. I/O gauges

If we had a Clue as to Which Engine you've got,.......... <br /><br />Maybe,.... Just Maybe,...... Somebody could tell you Where to Look for the Sending Units....................

 

[Mischief Managed]

Re: Merc. I/O gauges

Willing to bet it's the main connector from the engine to the boat that's a little loose. Should be a big round multipin connector with a rubber boot.<br /><br />Here's a generic picture of one:<br />

 

[rodbolt]

Re: Merc. I/O gauges

the switches for temp and oil alarm are different than the sending units for temp gauge and oil pressure and are an option. quite a few boats were rigged without the audible alarm option.<br /> so you may or may not have the switches.<br /> if both gauges are flaky look for the ground or 12V power supply from the ign switch to the gauges.<br /> most makes have the wires piggy backed from gauge to gauge and if one connection gets weak it affects the others downstream of it.<br /> in other words quite a few are wired in series.