Most engine electrical problems are caused by easily fixed issues.
Many years ago I went to a weeklong tech school about engine electricals. The first day opened with a guy talking about battery construction. As far as I was concerned, that was a 10-minute lecture, but he was well into four hours when we broke for lunch. Ever Mr. Polite, I asked when we’d be getting into engine electricals. He replied that all he knew was batteries, and that would be the topic for the whole five days! Maybe I should have stayed, but I went back to the motel, packed and went home. Here’s what I had hoped to learn that week, which has taken years to assimilate.
I can’t count the number of times a week I hear that an engine won’t start. I hear that starters have been replaced; ignition switches unwired and replaced; batteries replaced; engine electrical cables replaced. Virtually anything that is engine-related gets a new home. What I find, though, is 99 out of 100 instances are O.E. — not meaning “original equipment,” but rather “operator error.” And most of it starts with dirty battery connections.
Dashboard items require very little current to operate. I hear, “The bilge works, and so does the horn, but the starter just says ‘unh.’ I replaced both batteries, but then all it did was click, so
I replaced the starter and now, nothing.” Let’s go to the first stage of repair, which should cost $0.
Battery cable connections are the prime culprit. Because they’re “out of sight, out of mind,” they’re like mushrooms in dark, dank holes, growing corrosion on the connections. Wing nuts come loose. Somebody told somebody who told somebody to put grease on the battery posts before installing the cables, so the owner did that and created another barrier to conductivity. The posts and cable ends should be spotlessly shiny, sanded with emery cloth and cleaned of all residue. Cables should not reflect any breakage under the sheathing. Connections should be made with no stressful bends on the cables and fastened with stainless lock nuts or stainless nuts and lock washers.
The more frequently a starter is engaged using poor battery connections, the quicker the brushes burn to a crisp, preparing the engine for a starter rebuild or replacement. A rebuild might be $50. A replacement can cost $150 to $600. Properly prepping the battery connections to prevent premature replacement runs as little as $0.
Batteries often get replaced because the real problem — cable connections — has been misdiagnosed. Replacing batteries without cleaning the connections achieves nothing. One might as well save money and leave the old batteries in. However, the usual problem lies here: I encourage DIYers to use tie wraps to bundle each group of wires before they’re removed from the battery posts. As each bundle is removed, note how many wires/cables are in it, then clean them all while retaining the tie wrap. Red goes to positive, black, yellow and green go to negative. A dual battery system, simply, has one positive cable to each battery from the battery switch. One battery has one negative cable to the negative post, and that cable connects to the negative post on the other battery. One of the two batteries will have the negative cable from the engine attached to its post. That makes a complete circuit. Most DIYers will drop one end of one of the negatives behind the batteries and end up with no response at all from the starter, or a minor response from both tilt and the starter as the engines may be grounded though the steering or ignition — but not well enough to work properly. Cost to “count sponges,” as the doctor says: $0.
Last, if you accidentally touch a positive cable to a negative already connected to a battery and the spark doesn’t blow the whole boat up, you probably have not escaped unscathed. Odds are you just blew the main engine fuse. Everything on the dash will work, but there will be no response from the engine when you turn the key. Turn the key to ON but not to Start. Does the tach or voltmeter work? No? Blown fuse. Does the power tilt work from either the control handle or the engine lower cowl? No? Blown fuse. It’s probably a 20- or 30-amp fuse, nestled near the starter solenoid. It could be a glass or tubular fuse, or a large or tiny spade fuse. Don’t replace it with one for higher amps, in case there’s a problem you can’t diagnose. Cost to replace the fuse: $2.
There you have it. Most electrical “problems” can be resolved for as little as $0, or as much as $2. Use the money you save doing it the right way to buy gas for the boat and enjoy life.