electrical system (MES)

[Stuart]

Help. I have MES (mysterious electrical s….) happening all over the classic 18. My system needs a total rework. I have mapped out the system and it resembles no standard. The best information that I have for the basic wiring diagram is an old mercury motor book. I plan to use heat shrink and crimps, the separate kind. Are soldered connectors a bad idea for saltwater use? Should I use the standard coast guard colors? Is there a wiring harness available for 18 feet? What is the best diagram to use? I have an ammeter and not a volt meter what is normal? And since I don’t trust the gages, what should I use and from who? My battery is under the back seat, where can I put a second?

Thanks guys.
Stuart.

[RickR]

If you have numerous eletrical problems it is probably a bad connection or wire between the dash (key switch) to the battery. Especially look for a bad ground.
You can make a jumper out of some wire and alligator clips to go from the battery to the dash.
Use a digital volt ohmmeter and check for voltage DROP ie. 12.70volts at the battery/ less under the dash. Sometimes the electronics have to be under a load (ON) to find the voltage drop.

Places I'd look are:
Bad key switch
Bad main wiring connector on engine
Bad ground

Buy a manual for your engine with diagrams.
Always use the correct gauge and color wire w/ADHESIVE LINED HEAT SHRINK.

Solder is not necessary if you have good crimpers and use them correctly.
You can buy a wiring harness for your engine but it would be expensive.
My "Seloc" manual has better wiring diagrams than "Clymer"

Donzigo had a recent post about a marine surplus in Sarasota with OE gauges and dash inserts.

[Stuart]

Thanks Rick. My problem is, I can crank the motor in the sling as many times as I want, no prob. After running the motor for a while and then try to restart, the battery is weak. Usually away from where I need to be. And, my tach sometimes goes nuts when the starter is engaged. And even in David O's driveway just sitting there. Then, recently my water temp shows zero until the motor is off and then it rises to 140. Tracing the problem, I have one color of wires from the units to the terminal to another color to the next terminal up forward again changing colors to a backwards setup at the instruments.
I got through the summer with quick fixes and have one cold month after Mardi Gras to fix this. To compound the mess, I have social pressure. My bud with Chi-Chi rebuilt his motor and is on the move with new power.
If this will help, I have a late 70s Chevy 350 mated to a Volvo 270 with a speedmaster. Are there books available for these?
I plan to use the adhesive. Used them once and they seal well.
I just got through rebuilding the motor and now I guess it is on to the electrons.
Thanks again.

[RickR]

Clymer and Seloc have Manuals for early Volvo.
Sounds like a bad ground to me. Try the jumpers.

[Stuart]

Madpoodle, I plan to get some new gages, so is the volt meter the way to go?
RickR, I have my jump suit on and will check the grounds.
Thanks for the info about the books.

[Ranman]

Stuart, I think volt meters are the way to go. Ammeters seem potentially dangerous to me since you have to run heavy guage wires from the back to the front. It's "old thinking". A volt meter will tell you what you need to know with much less fuss.

[Stuart]

Ranman, I have checked a couple of other classics and they both have volt meters. I have always wondered about this heavy wire going forward.
Hey, nice boat.

[Digger]

Stuart,
I'm no electrical genius. I highly recommend this book: "Boat Owner's Illustrated Wiring Handbook"
By Charlie Wing
available from BoatUS or West Marine or some of the larger bookstores. It is awesome, takes you from the basics on up, for me it is as relevant and valuable to have on your shelf as Chapman's. good luck