dpal
Cadet
- Joined
- Apr 28, 2009
- Messages
- 15
I have a 1993 Mercury outboard 40 hp ELPTO 4 cyl 2 cycle. This motor is new to me and was running good the 2 times I have had it out on the water except for some sputtering at around 10 mph. I ordered a factory manual so I could check all adjustments. I first noticed the carb linkage wasn?t allowing full throttle while on the trailer. I did not look while running on the water but the RPM on the water is reaching about 5300 at about 29 mph (gps). That seamed average to me for a Pro 17 bass tracker. The motor was idling in the water about right below 800 RPM ? but will not start without choke for a second hot or cold. Now, here?s my problem. Compression equal at 125 psi. I checked the timing using the starter method and it was set to about 6 ATDC, the book said 2 BTDC - 2 ATDC. At full throttle 32 BTDC using the starter method with spark plugs removed. When I set up the timing per the book, I get a high idle situation of 1000-1100 out of the water on water muffs. The carb butterfly valves are closed with no linkage touching. The book says 600-700 RPM in gear in the water. My question is can anyone tell me from experience the difference in idle RPM out of the water and then in the water. I am wondering if the prior owner or tech set the timing lower to achieve a lower idle. It is about 1 hour to the nearest lake to test and I would rather try to get it right at home. Sorry for the long post but I know how important setup info can be.