Thanks Bondo! I replaced the plugs last season, so I'll run with Delco plugs.
As far as the problem(s)...I'm about two years into repairs and maintenance on a boat that was somewhat neglected prior to me buying it. The main and most troublesome problem has been motors stalling at idle under load. The problem never shows itself on initial start-up, but only after the boat has been driven for some time.
Just so you have a little of the backstory...I have over the last two years replaced and/or performed regular maintenance on all of the typical tune up and basic process of elimination items on the motors:
spark plugs (not wires yet)
dist cap and rotor
fuel filters (in-line, water separator, carb inlet)
oil/filter
ignition coil
RW impeller
thermostat
Rightly or wrongly a lot of effort has been focused on fuel, to the point where I've even cut about 1" off the fuel tank pick-up tubes to keep from pulling crud from the bottom of the tanks. After all the work and troubleshooting I was still struggling with probelms at the beginning of this season.
Good news is...I had a friend/mechanic help me troubeshoot the problem last week and with two successful sea trials under our belt it looks like it might be solved...timing. Base timing was at spec 6 deg BTDC, but I never checked TAT. So we adjusted the timing by ear/feel while out on the lake, trialing at various RPM's, nuetral/restart, idle, etc. I realize not by the book, but after so many failed attepmts including qualified marine mechanics, I had to try someting.
So here's next setps that I'm thinking
1) put a timing light back on the motors, check base and TAT
2) plugs ok, but replace wires...Question, Sierra Magforce Sprial Core?
3) Check mech. fuel pump pressure, even though I don't think my fuel pumps are bad, I'd still like to know what fuel pressure the pumps are delivering.
Thanks Again!
