Good advice, so far.
Fuel & electrical are possible culprits, but rarely, if ever, is the starter as a problem as you've described, so you can sleep easier tonight.
The battery cable sizing is fine, unless the PO changed something.
It's rarely the start button.
The most COMMON situation is the connection of the electrical system GROUND wire from the batteries to the engine. In most cases, this connection is made right behind the alternator on the bell housing of the engine, below the exhaust manifold. The old 1988 wiring may not have been tinned ire (mine aren't) and you may actually physically be able to simply pull it out of the lug with a little hand pressure. Check that first, or do the separate battery trick.
One other possibility: If there is NO NOISE whatsoever, and the starter doesn't even make a peep, then check the inline fuse in the wire from the start button to the starter solenoid. It, too, is cleverly hidden behind and under the alternator. While this was discussed in the Tech Notes a few times many years ago, it saved my bacon once on a cruise because I had that problem, but I remembered reading about it. I relocated the fuse holder to a place more accessible. See Reply #3:
http://c34.org/bbs/index.php/topic,4556.0.htmlI discourage the use of the decompression lever, ever. It's something the old C30 guys got used to. We, here, tend to address the issue a bit more elegantly: we design and install good solid electrical systems so the engine starts, right away, all the time.
If you need help to learn the parts of the engine, go to
www.marinedieseldirect.com, find the M25 (or XP) engine and print out the photos, they show both sides of the engine.
If you need help to find yourself around this website, please read the Quick Start Guide, a sticky on this board, here:
http://c34.org/bbs/index.php/topic,5260.0.htmlYou will soon learn two important things:
1. When it's electrical, it's usually NOT the electrical system, batteries or other parts: it's the CONNECTIONS
2. The amount of use a boat gets is inversely proportional to the amount of reported operational problems!
