1971 60hp 3 cylinder

Boat sat for many years till I got it last year. Did minor stuff (spark plugs) and got it ready to go in the water. Starts great, runs great through throttle range. So we are moving to another fishing spot. Decided to go full throttle. Boat ran like a new boat showing off. At least for 200 yards then power decreased about 50%. Lowered throttle and put in neutral. Throttle will go full in neutral. Put back in forward and have abut 50%. So, we decided to fish. Started boat about 1/2 hour later and it ran fine at full for about 200 yards then then went to 1/2 power. Idles fine, no backfire. Ok, so where do I start?

Possibly the engine is overheating? Check the warning horn as follows:

(Testing Warning Horn)
(J. Reeves)

On VRO equipped engines where the VRO automatic fuel/oil setup is still being used, make sure that all components are connected as required. This would include the VRO pump wiring harness itself, the oil tank wiring, the overheat sensor(s), and if so equipped.... the vacuum switch that is standard to many V6 & V8 engines.

If the VRO automatic setup has been eliminated and has been disconnected properly, and the fuel and oil is being premixed, make sure that the overheat sensors are still connected, and the vacuum switch if the engine is so equipped.

On engines prior to 1984 which have no VRO setup, ignore the instructions pertaining to the VRO components, etc above.

Turn the key to the ON position (Engine Not Running). Find the TAN wire at the cylinder head(s), then ground out the portion of that wire that is part of the engine wiring harness. If that Tan wire connector has the knife type connector where as it is exposed simply by sliding the rubber insulator back, it does not need to be disconnected.

Grounding that TAN wire should cause the horn to sound. If it does not, find out why as that's the only warning you'll receive should the engine overheat or have some portion of the VRO system fail, or have the engine encounter a fuel restriction if it is equipped with a vacuum switch.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1

Pull the flywheel.--Then remove distibutor rotor and the cap.---Then inspect anti-reversing spring.---Clean and set points to 0.010" and reassemble carefully.--Torque flywheel nut to 100 ft-lbs.-Test run.

tdgray said:

Boat sat for many years till I got it last year. Did minor stuff (spark plugs) and got it ready to go in the water. Starts great, runs great through throttle range. So we are moving to another fishing spot. Decided to go full throttle. Boat ran like a new boat showing off. At least for 200 yards then power decreased about 50%. Lowered throttle and put in neutral. Throttle will go full in neutral. Put back in forward and have abut 50%. So, we decided to fish. Started boat about 1/2 hour later and it ran fine at full for about 200 yards then then went to 1/2 power. Idles fine, no backfire. Ok, so where do I start?

Click to expand...

Uh-huh, and what spark plugs did you put in it? If you put in the original surface gap plug type, that was a mistake. Use Champion L77C4 or QL77JC4. I got most of these grey hairs trying to make those engines run right, till I discovered the plugs secret.