I finally had a chance to work on this problem again (original posted below). Thanks to the advice I received on this from the good folks here I had some ideas to try. First, I found the engine wiring diagram in the Yanmar manual. Next, I found the in-line fuse near the starter. The fuse was fine (so much for the easy solution). Next I jumpered across the starter and the motor cranked. Cool, at least it's not an expensive part! Then I took the panel off the side of the console that holds the key switch, start button etc. I had power when I turned the key on, but when I pressed the start button, the result was same as before - the fuel gage went from 3/4 full to empty, and the power / charging light went out, like all the power was suddenly "gone" when the start button was pressed. In messing with the bundle of wires with the key turned on, occasionally the light would go out and the fuel gauge would lose power, so I knew I had a loose wire somwhere. Just to be sure, I used another piece of wire and bypassed both the key switch and start button, and the results were the same as with the switches in place. Next, I unplugged the starter wires (there is a plastic junction in the wire run). I jumpered across the wire tabs in the junction, same results. That meant the problem was somewhere between that junction and the starter. The last clue was that in moving wires around I would see the charging light glow dimly and brightly. Also, the alarm would vary in volume. So...my theory is the positive wire is damaged or has a loose connection. When I get it to connect, it connects enough to light the light, but when I hit the start button, the current draw is more than that tenous connection can handle, so the light goes out and the fuel gauge drops to empty. I plan to run a test wire from the battery to the starter switch and see if that does the trick (didn't have a long enough wire with me tonight). Any thoughts? --- previous post Ignition short? Submitted by Sailor Joe on 02/26/2005 at 09:09PM regarding Hunter 320. I need some help with an electrical problem. I'd been away from the boat for about 6 weeks, and upon returning I found I'd left the key in the key switch in the ON position. The boat was on shore power, so the batteries were fine, but when I pressed the button to start the motor, no cranking occurred. The fuel gauge, which comes to life when you turn the key on, went to empty when I hit the engine start button, as if pressing the engine start switch shorted out the circuit. When I would operate the key switch, it didn't act right, and didn't turn ON regularly. I had to turn the key several times to get a connection. I wanted to test the engine start switch, so I jumped across the terminals and got a spark, but no cranking. Upon further reflection, I got to thinking that the key switch may have been partially shorted, so when I jumpered across the engine start switch, there was a spark but no cranking. Today I went back to the boat and took the key switch out of the loop, but no help. In fact, the fuel gauge didn't come to life, and it seemed that I had no power at all to that circuit. All other electrical apparatus on the boat work fine, and the batteries have a full charge. Because I have no power at the switch, I am concerned that a fuse has blown, but I cannot find a fuse anywhere. I tried to follow the wires down the console and through the boat, but can't see them everywhere, so I don't know if there is a fuse inline somewhere. So, I am wondering if there is a fuse protecting the key switch/start button circuit? I am also wondering if anyone can point me to a schematic for this circuit? I've gone through the manual thoroughly, and can find no drawing for any of the circuits in the console. All advice appreciated!
Ignition Short - Update
- Thread starter Sailor Joe20804
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right track
Sounds like your on the right track. Just another pointer though, you may also have a bad ground at the gauges, but this should not effect the start button. Not sure how to help you at this point as your (in my opinion going about it logically) except to say that in helping to determine where the short or bad wire is, is to firmly hold the mass of wires with one hand and use the other hand to move them around, making sure that the hand holding them firmly in place doesn't move, and you should be able to figure out which direction to go after.
Sounds like your on the right track. Just another pointer though, you may also have a bad ground at the gauges, but this should not effect the start button. Not sure how to help you at this point as your (in my opinion going about it logically) except to say that in helping to determine where the short or bad wire is, is to firmly hold the mass of wires with one hand and use the other hand to move them around, making sure that the hand holding them firmly in place doesn't move, and you should be able to figure out which direction to go after.
draw a rough diagram
then look for common points of failure - the key swtich connections, the wire supplying poitive voltage to the key, and check these. Or replace the wires. By the way...key on, engine not running should produce an oil pressure light or alarm, this circuit may be part of the prblem.
then look for common points of failure - the key swtich connections, the wire supplying poitive voltage to the key, and check these. Or replace the wires. By the way...key on, engine not running should produce an oil pressure light or alarm, this circuit may be part of the prblem.
My Yanmar has two junction plugs.
I think you referred to them as the 'plastic' plugs. They have a rubber boot to seal out water. Pop each one open and look for failed connections. The entire harness is replaceable from your local Yanmar dealer if it comes to that. My original plugs had bad connections. I bypassed them by soldering jumpers. What a pain. But it worked. It is much easier to just replace the bad sections. I've since replaced mine. Good luck. And thanks for the feedback.
I think you referred to them as the 'plastic' plugs. They have a rubber boot to seal out water. Pop each one open and look for failed connections. The entire harness is replaceable from your local Yanmar dealer if it comes to that. My original plugs had bad connections. I bypassed them by soldering jumpers. What a pain. But it worked. It is much easier to just replace the bad sections. I've since replaced mine. Good luck. And thanks for the feedback.
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