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Just finished rebuilding / respraying this battery alternator motor, connected up all the wiring to setup the choke solenoid and check the starter motor function. When using the key starter I can see arcing / sparks at the choke solenoid plunger, the tray-to-powerhead earth mount on the tray below the fuel pump and the base of the starter motor. I’ve gone thorugh the wiring at the switch / terminal block and made sure that’s to the manual spec & looked for obvious signs of anything touching, a few times. The battery negative is grounded mounted to the LH bolt of the choke solenoid – even scraped paint back to expose metal there. I suspect I am missing the obvious, but am not an expert at electrics, so would appreciate any advice.
The ground cable from the lower tray to the powerhead is on the left, with the battery ground to the right of the choke solenoid. I went back to the early pic 7 years ago, just to check (I once had a 45hp magento motor that had a ground cable directly to the block. The 55hp appears to be a workaround given the 2 external coils, mounting bracket and the regulator – I did think of mounting it to the starter motor bolts, but it’s kind of crowded…).
I still say there is a grounding problem at one of those cables. I’ll ponder and think about it awhile.
EDIT: OK, I pondered. Gotta be a problem with that bonding cable between the powerhead and tray. Or I’m fooled.
EDIT, EDIT: Rats, I’m still pondering. Sparking at the base of the starter??? I can’t think of a reasonable excuse for that. This calls for some voltage drop tests or disconnecting one devise at a time (choke, starter).
It is hard to say, sitting here….But if you have arcing at the choke solenoid plunger, that would seem to indicate that voltage is looking for a path to ground from the carb, across the gaps between the plunger and the choke solenoid, to your good ground on the lower pan. (I hope there is no GAS in that carb, yet!) As for arcing at the base of the starter, you may have a secondary connection problem, possibility caused by your nice paint job. Like Frank said, a voltage drop test or two across the suspect areas will tell the tale. To start with, put one lead of a volt meter on a good, clean, bare spot on the block and the other lead on the ring end of the ground cable bolted to the lower pan. Crank the engine and observe the meter. Any movement of the needle (or digital voltage reading higher than zero) indicates you have a problem between the main cable at the pan, and the block.
Long live American manufacturing!
I picked up on the paint job comment and removed a few layers of new primer and paint on the tray side and and cleaned up the terminals – between there and the block. All works spot on now, no arcing. The choke plunger had been doing some brazing. Need to say thanks to you both. Here’s a pic of the boat & motor just before it ‘s death rattle – looking forward to many more years of use.
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