Hour Meter Wiring

[MaxGlide]

1978 Mercruiser 140. Simple hour meter with two wires. Just double checking. Is One wire to ground and one wire to ignition switch correct way of connecting?

 

[Bt Doctur]

one wire to ground, one wire to ignition hot

 

[johnkom]

I wired my hour meter a little differently. Since you are supposed to run the engine vent fan for several minutes before engine start, the electric choke would always be in the full hot position since the key had to be on to run the fan. I decided to wire the electric choke power through the oil pressure switch. While at it I wired the hour meter that way too. Then it only runs when the engine is actually running. See my schematic.

 

[MaxGlide]

I wired my hour meter a little differently. Since you are supposed to run the engine vent fan for several minutes before engine start, the electric choke would always be in the full hot position since the key had to be on to run the fan. I decided to wire the electric choke power through the oil pressure switch. While at it I wired the hour meter that way too. Then it only runs when the engine is actually running. See my schematic.

Yeah, I get that if you wire it to the ignition that it will log false time if you have key in with it not running and that it’ll add the bit of time we run the fan and not the engine. But we can live with that. (It’s a 1978!)

 

[alldodge]

Normally the blower is run direct from the Bat (thru fuse) so key ON is not required

 

[Scott06]

Normally the blower is run direct from the Bat (thru fuse) so key ON is not required

Exactly. I never had a boat wired so the key had to be on for the blower to run, should be hot all the time

 

[Scott Danforth]

agreed blower should be able to run any time the batteries are on

half the boats in existence do not have an hour meter.

my key switch has an accessory position that I use for accessory loads. ignition is only for engine ignition, gauges and the hour meter.

Hour meter is only used as a rough measure for maintenance.

 

[nola mike]

Never really understood the hour meter. 100 hours at idle isn't the same as 100 hours of watersports. Same thing with mileage in cars... I'll take 100k highway over 20k city (or my wife driving) any day.

 

[achris]

This is how you should wire a boat...

 

[MaxGlide]

This is how you should wire a boat...

View attachment 355950

Wow! this is awesome! Thank you so much.

 

[AKJohne]

Hour meter could be wired to a oil pressure switch, that way the clock is only ticking when the engine is actually running, more wires to the helm unless you put the Hobbs meter near the motor.