1962 28hp seahose cutout switch

[kevinwd1]

Just wondering how the cutout switch that?s controlled via a diaphragm and the switch under the flywheel works. I assumed that it would cut the spark if the throttle was to far open when trying to start the motor. Once the motor had been started the crankcase pressure would cause the diaphragm to override the switch under the flywheel thus allowing you to get full throttle .The problem is that I get spark no matter what position the throttle is in which proves my theory to be incorrect. Would love to be enlightened

Regards Kevin

 

[lindy46]

Re: 1962 28hp seahose cutout switch

The cut-out switch grounds out the bottom spark plug in case of a runaway situation, to slow down the RPM's. High vacuum closes the ground circuit in the switch. Is that the switch you're talking about? There is also a neutral safety switch which only allows the starter to crank when the shift lever is in neutral. They are unrelated as far as function goes. In neutral, you should get spark to both cylinders when cranking the engine. There is a "stop" on the magneto which keeps you from advancing the throttle past the "start" position in neutral. If the neutral safety switch is working and wired correctly, the engine should only crank in neutral. The only time the cut-out switch comes into play, is if the engine revs too high. Under normal running conditions it has no effect on the spark to either cylinder.

 

[kevinwd1]

Re: 1962 28hp seahose cutout switch

Thanks lindy46, I understand how the vacuum switch works now, but I’m still unsure what the electrical switch under the flywheel does? It’s on or off depending on the position of the throttle and is wired in to the vacuum cutout switch. I only have manual pull start so would this mean that the neutral safety switch is redundant. The motor has been sitting for 5 years and we are about to pull the carb off and clean it up. Any advice on things to check would be appreciated. This is the first time I worked on a outboard motor so it’s a bit of a learning curve.

Regards Kevin

 

[lindy46]

Re: 1962 28hp seahose cutout switch

There should be a lockout lever on the top front of the pull starter which moves up and down, and locks the pull start from pulling (in the down position) if the throttle is advanced too far. The neutral safety switch is activated by the shift lever, not the throttle. Possibly your motor had an electric starter at one point.

 

[F_R]

Re: 1962 28hp seahose cutout switch

If I may clear this up a bit..... The vacuum cutout switch is there to slow the motor down to a safe level in event of a runaway condition as previously stated. This is especially important in a manual start motor with no ignition switch to turn it off.

Now, for the rest of the story. Note that the vacuum cut-out switch is mounted on a plastic plate. That means the vacuum switch body is not grounded to the powerhead. Not being grounded means it will do absolutely nothing if it closes in event of a runaway. THAT is what the switch under the flywheel is for. It grounds the vacuum switch body so it can function, but only at slower throttle settings. If it were grounded at all throttle settings, it could cause a hard to diagnose miss at certain throttle settings, especially at "cruise throttle" position.

The switch under the flywheel serves double duty on electric start motors, by preventing starter operation at high throttle settings. Think about that: You can only open the throttle when in forward gear. If the switch didn't prevent starting under that condition, you could start the motor in gear at wide open throttle....and pitch somebody out of the boat or run over something or somebody. The recoil starter lockout serves the same function.

Everybody clear on that now?

 

[kevinwd1]

Re: 1962 28hp seahose cutout switch

Thanks for your replies, it all makes sense now

Regards Kevin

 

[HighTrim]

Re: 1962 28hp seahose cutout switch

This system is far superior to the cut out switch/mercury switches before it in my humble opinion. Id like to try to fit the newer style safety switch to a 50s OMC Big Twin one day.