Engine wont stop

[twarnold]

started my engine the other day and it idled ok then started to rev so high i could not turn it off with the key i had to put my hand over the carb .in the past i have noticed when in neutral i give it a rev it will increase in rev by itself but not as bad as now trying to get it ready to take out but not with this problem. details of outboard are 45hp chrysler outboard model 455hg 1970-75 i think,any help would be appreciated.

 

[mthieme]

Re: Engine wont stop

Sounds like you need a new switch. These run less than $20.
The revving is a different issue. With only that one tidbit of info, I would guess it is carb related.

 

[twarnold]

Re: Engine wont stop

no its not the switch basically what is happenig is i turn the engine on it idles ok for say about 30 seconds and i can turn off the motor no problems but if i leave it to idle eventually it revs out of control sorry i havent got any other info on the problem but il check the carb thanks

 

[wilgil]

Re: Engine wont stop

Back in the old days it was good practice to turn the fuel off on your 2 stroke motocross bike and idle until the carb. emptied itself of fuel. The engine would idle normal for about 30 seconds and then rev. really high as the mixture leaned out. I never liked doing this, so I stopped and just put up with the bike running a bit rough on start up for a while until the old fuel was mixed with new incoming stuff. Could it be possible that your fuel flow might be impaired? Just a thought. Obviously it's a problem with the carbs. at any rate, but I thought this might point you in a possible direction.

 

[mthieme]

Re: Engine wont stop

I'm sorry, I misunderstood.
It won't shut off because it is idling too high - correct?
This could be a simple carb adjustment.
This summer, the stop nut for my idle adjustment loosened up on one of my motors. The screw worked itself in and as a result idled high.
You might also want to check for an air (vacuum) leak. Hold a rag over the carb (or carbs one at a time) and see if the rpms raise.

 

[twarnold]

Re: Engine wont stop

yes thats right ,i will check all these things while im at it is it worth checking the float level is adjusted right ,something else that should be easy to cancel out as not being an issue.

 

[Tim Frank]

Re: Engine wont stop

Why would idling too high make it not shut down when the ignition is killed?

 

[mthieme]

Re: Engine wont stop

It's called dieseling or run on. I'm sure at one point you've heard a car do this. Ignition is typically caused by a hot spot in the cylinder, perhaps a piece of carbon stuck somewhere. Other than the high idle, timing being off can cause this too.
The float level is not going to matter.

 

[Tim Frank]

Re: Engine wont stop

It's called dieseling or run on. I'm sure at one point you've heard a car do this. Ignition is typically caused by a hot spot in the cylinder, perhaps a piece of carbon stuck somewhere. Other than the high idle, timing being off can cause this too.
The float level is not going to matter.

Sure....pre-ignition.
Haven't personally heard of this with 2-strokes...but the theory should be the same as 4 strokes.
Thanks.

** except that he said it "revs out of control"....and with the hot-spot induced run-on (I have some British heritage and am used to calling it "run-on") it usually is pretty rough and it does stop after some seconds, and I've never seen it "rev out of control".

It might be useful to know how long it continues to run and/or how he stops it.

 

[mthieme]

Re: Engine wont stop

I agree, it's not as common.
I've only had it happen the one time when the idle screw screwed up on me.
But, there are a few things for you to check out.
Wouldn't want you to stay in front of that nice cozy fire place all winter!!!

 

[twarnold]

Re: Engine wont stop

Why would idling too high make it not shut down when the ignition is killed?

dont know thats what im trying to find out