Outboards running on

[orca]

G,Day.<br />recently I have had a few problems with outboard motors running on. For example, I have started the motor, running on the flusher and the revs have gone instantly to abour 6000RPM, If you turn off the key the motor will still run. If you pull off the plug leads the motor will continue to run. the only way to cut the motor is to choke it or operate the enrichener. I have had three motors with this problem in receny months. two were OMC 2 cylinder 60HP and one was a Suzuki 70HP. all motors were oil injected. I am wondering if the motors were "dieseling" on the oil from the oil injection system. has anyone else seen this problem.

 

[rodbolt]

Re: Outboards running on

Hello<br /> its called a runaway. its not caused by oil ingection. its caused by exssive no load speeds.the old jonnyrudes of the 33,35 and 40 hp had a vacum switch to prevent this. I must say that if you pull the plug wires you still have a deal. the motor is igniting the fuel mix from compression heat alone. its hard to belive that with the motor running away you stand there and pull wires. nerves of steel.<br /> I would adjust my cold start procedures.<br />I did see one mid 80's 35 that got sohot it ran away until the engine lost compression. remember it must suck squeeze bang and blow or its just a pretty piece of casting.<br /> good luck and keep posting

 

[DJ]

Re: Outboards running on

whaley,<br /><br />Hot spots (glowing carbon) in the combustion chambers is providing the spark.<br /><br />The phenom. is indicative of engines that are badly carboned up. oil injection has nothing to do with it.<br /><br /> Do a decarb and that issue should go away.

 

[orca]

Re: Outboards running on

G,Day.<br />Thanks guys, I have been working on outboards for 30 Years and I have only seen this problem recently. Maybee modern fuels have contributed to this problem.

 

[seahorse5]

Re: Outboards running on

I believe there was a bulletin about "runaway" late model 40 and 50hp OMC's. They said not to rev it in neutral, especially on a flusher. If it did start gaining rpms, then push the key switch IN to give it more fuel to slow down. I understand it was a combination of engine design, fuel quality, carbon deposits, and a lean condition.