I found a number of posts on the forums for a wiring issue that Hunter had with the starter wiring, where the switch or the wires would prevent the starter solenoid from starting the Yanmar (or other engines?). This was apparently due to small wires in the harness or bad contacts in the starter switch. The common fix is to put a relay in the starter circuit.
I haven't had the problem in my '88 28.5, Yanmar 2GM20F, but I figured that I'd do some preventive maintenance and add the relay. I built up the relay at home with about 6" of wire on each lead, then added the connectors that I needed when I installed it on the boat.
I used a heavy 12V relays that I happened to have in my junk box, but you can purchase a 12v automotive relay at most auto supply stores (most have spade lugs rather than the solder lugs that I happened to have). I added some smaller 16 gauge wire to the + and - terminals from the coil of the relay. I then added two heavier 12 gauge (red) wires to the contact terminals.
Installation was to remove the smaller z(lower) of the two wires from the starter solenoid and connect that wire to the + side of the relay coil. The negative side of the relay coil gets connected to the large ground lug on the bottom of the starter. One side of the large relay contact wires goes to the large + (red) wire on the top of the starter relay and the other contact wire goes to the lower starter contact wire where the wire was removed from. I then used tape and tie-wraps to strap the relay and wires to the existing harness wires. Works Great!
NOTE: You may want to consider adding a 2 amp fuse in the line + coil line. Simply cut the wire and add 2 spade lugs, wrap the lugs with black tape and insert the fuse. Then wrap the two terminal lugs together with some more black tape to keep them in position if you remove the fuse.
You may notice that I have a diode between the two coil wires on the relay. This is called a "snubber" diode, intended to suppress the coil kick back when the contacts open. Considering that the starter relay doesn't have the snubber diode, I don't think that the relay needes it either. You can omit the diode.
I haven't had the problem in my '88 28.5, Yanmar 2GM20F, but I figured that I'd do some preventive maintenance and add the relay. I built up the relay at home with about 6" of wire on each lead, then added the connectors that I needed when I installed it on the boat.
I used a heavy 12V relays that I happened to have in my junk box, but you can purchase a 12v automotive relay at most auto supply stores (most have spade lugs rather than the solder lugs that I happened to have). I added some smaller 16 gauge wire to the + and - terminals from the coil of the relay. I then added two heavier 12 gauge (red) wires to the contact terminals.
Installation was to remove the smaller z(lower) of the two wires from the starter solenoid and connect that wire to the + side of the relay coil. The negative side of the relay coil gets connected to the large ground lug on the bottom of the starter. One side of the large relay contact wires goes to the large + (red) wire on the top of the starter relay and the other contact wire goes to the lower starter contact wire where the wire was removed from. I then used tape and tie-wraps to strap the relay and wires to the existing harness wires. Works Great!
NOTE: You may want to consider adding a 2 amp fuse in the line + coil line. Simply cut the wire and add 2 spade lugs, wrap the lugs with black tape and insert the fuse. Then wrap the two terminal lugs together with some more black tape to keep them in position if you remove the fuse.
You may notice that I have a diode between the two coil wires on the relay. This is called a "snubber" diode, intended to suppress the coil kick back when the contacts open. Considering that the starter relay doesn't have the snubber diode, I don't think that the relay needes it either. You can omit the diode.
