What's this? Off my 1980 20' wellcraft with mercruiser 4.3 engine

Brian922344

Recruit
Joined
Jul 31, 2024
Messages
4
Inherited this boat halfway through repair and this was one of the parts.
Trying to upload a picture but it won't allow me.

It seems to be a relay.
Black plastic box no writing on it about 1 in dimension on all sides.

was bolted to the top of the thermostat housing.

Has four wires coming up from it;
Two black wires, a white wire and a red wire
 

ScottinAZ

Master Chief Petty Officer
Joined
Jun 25, 2009
Messages
831
most likely exactly what it is, a relay. Red is likely 12v power, white is 12v triggered, and the blacks are grounds. you will need to check the manual for your engine/boat to be 100% sure though
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
49,538
If your boat has a 4.3 in it, it was transplanted.

The 4.3 came out in 1985
 

nola mike

Vice Admiral
Joined
Apr 22, 2009
Messages
5,362
Not stock, where do the wires connect? Does it have an electric fuel pump?
 

nola mike

Vice Admiral
Joined
Apr 22, 2009
Messages
5,362
That's a possibility, I think the pumps were mechanical until at least the balance shaft engines. I guess trace the wires, or see what your oil pressure switch looks like. Factory switch was 2 terminal, if relay is used it's likely 3 terminal.
 
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