Engine would not shut down

[StriperJim]

I have a Chrysler 105 Hp Model: #1057HB Ser.# 1108 Have not had it long it is on a 18.5 ft. Caudy cabin build in ****erson Tenn. About everthing is org. (1971) The engine runs great was going down the lake about 4000 RPM and Prop. bushing sliped out & and the engine Rev. up and I could not get it to shut down it scared me and my wife bad, she was about to jump in the lake. I have put a switch from the coil hot side to the dash and back to the coil to cut the fire of it. I can not stand it doing that again? My quesion will that take of it I have heard that some that runns a way it might not help. But I want to shut it off when this happens???? Jim

 

[eurolarva]

Re: Engine would not shut down

If you motor runs away I doubt the kill switch will help. When you turn the ignition switch off you are basically doing the same thing. Have you decarbed the motor? This could be part of the problem. The excessive carbon build up is like adding coal to a fire. Your spark plugs are not creating the burn. I have read here the best way to stop a run away motor is to stuff a rag into the carburator. I dont know If I would want to try and figure out how to take the cowling off on that angry motor and smother the carb. I am with your wife abandon ship.

 

[StriperJim]

Re: Engine would not shut down

Thanks Eurolarva,<br /> No I have not decarbed the motor, you are right I did not want to get too close to the run away engine, I love this engine & boat but if it happens again I might get another engine the engine does not have many hrs. on it,from the history that I have found. Jim

 

[eurolarva]

Re: Engine would not shut down

Look at the Frequently Asked Questions forum on decarb. There are some good procedures in there. I would recommend doing it in a test tank and make sure you do it a good distance from your garage or house. If it is really bad the smoke coming out could stain your siding.

 

[12Footer]

Re: Engine would not shut down

Welcome to iboats, Jim.<br />I have had this happen in my driveway on a 50HP, on the muffs. All 2cycle outboards are susceptable to this freak-thing.<br />Eurolarva is correct, from what I have learned.<br />Running on the muffs, or overheating can make this happen to.<br />The carbon inside the combustion chamber will act like a glow-plug, becomming an ignition source ,even with the key off. Not only that, but as the ignition occurs, it draws more fuel into the intake,which allows for even more fuel. The result; runaway!<br />It's damaging,if it cannot be stopped. Whatever you have to do to shut it down, do it.<br />I used water from the garden hose,directly down it's carb.<br />Check the motor for adequate cooling, and decarb often.

 

[eurolarva]

Re: Engine would not shut down

From what 12 footer says another thing is disconnect the fuel line from the gas tank. It will take awhile but at high rpms it should run the gas off pretty quick/

 

[TOOSTROKIN]

Re: Engine would not shut down

THIS IS VERY COMMON ON SMALLER JET SKI ENGINES. THE BEST WAY TO STOP THE ENGINE WHEN THIS HAPPENS IS FULL CHOKE. WORKS EVERYTIME. I HAVE HAD THIS HAPPEN SEVERAL TIMES ON MOTORS WITH NO LOAD ON THEM. AN AIRLEAK IN THE MOTOR WILL ALSO CAUSE THIS. BAD CRANK SEALS OR CARB GASKETS WILL CAUSE AN AIR LEAK. IF IT HAPPENS TO YOU AGAIN GIVE FULL CHOKE TO SHUT IT DOWN.

 

[rodbolt]

Re: Engine would not shut down

hello<br /> are you sure your cutoff switch is wired correctly?<br /> most the time it either wires up from the magneto terminal to ground and some wire normally closed and open for kill. what ignition system are you running? if there was enough carbon to cause it to diesel it would be dead already. I have seen some overheats on small motors that caused a runaway and they ran till a head gasket blew due to lack of cooling.<br /> but it would not be the first swith I ever saw miswired. some after market switches can be wired normally open or normally closed depending on which connectors you tap. if you really want to see a runaway have the fwd shift wire break when crusing at 4K on an old omc <br /> that was interesting.

 

[DHPMARINE]

Re: Engine would not shut down

Just think how you and the wife felt afterwards!!<br />A small joke,but a run away engine is no joke.Ignition is supplied by a hot spot in the cylinder,and will keep the motor running even with the plug wires off.<br />Bad part is runaways go to peak RPM's and higher.<br />Only way to stop is....<br />No air or no fuel.<br />Or ....mechanical.That's when you duck.<br /><br />DHP

 

[fixin]

Re: Engine would not shut down

A runaway is a scary thing.I had a 2stroke motorcycle do it once.Luckily it was in the driveway,I thought I was smart,pulled the plug wires off,still full blast!!!Next thing was cover my face,shut the fuel off and run!It finally quit.I believe it was a bad crankcase seal that caused the runaway.It seemed fine after I replaced it,but I never trusted the thing again and sold it.Be careful!

 

[StriperJim]

Re: Engine would not shut down

Thanks, Guys,<br /> Eur., 12foot, Toost., rodb., Fixi.,DHP, I am going to carry the boat out next weekend and I am going to Decarb. the engine I went and made a copy of how to do It. I like the seafoam in a jug better. I made a note to pull the choke if it happends abain, and it has the org. switch on it with 6 wires on it I am going to see if I can find out how it is susposed to be wired. I am going to put a inline gas cutoff on it also.<br /> I do use this to Troll alot about 900 RPM for 3 to 4 Hrs. at a time. <br /> Thanks for all the info. I will decarb it before I use it again. If I do all of this maybe my wife will go out again.<br /> Jim

 

[StriperJim]

Re: Engine would not shut down

Thanks for the Imput I Decarb. this engine Monday, using the 1 Gal. Jug it worked great but I did not have much smoke after 15 min. of shut down time. I could tell it ran better after 2 times of decarb. But why did it not smoke much I know that this engine has never had this done to it.<br /> Jim J

 

[DJ]

Re: Engine would not shut down

Jimmy,<br /><br />If you can, run a heavy dose of decarb through it and let it sit overnight.<br /><br />Allot of the gunk that was in the combustion chambers may have run out of the exhaust is liquid and solid form.<br /><br />I agree on pulling the choke on a runaway, in conjunction with pulling the fuel supply. The choke may not kill it but it will at least slow it down.

 

[StriperJim]

Re: Engine would not shut down

Thanks DJ<br /> I am going to run it after New Years, & I will try that. I will keep in mind on pulling the choke out. Jim

 

[StriperJim]

Re: Engine would not shut down

Hi <br /> We out this past week end and road about 3 hrs. at 3800 RPM, The motor ran good we stoped twiced and took of again, it used about 10 gal. of gas does that seem norm. We went about 30 miles. The 105 chrs. ran great, why does it uses so much gas.<br /> Jim

 

[Elmer Fudge]

Re: Engine would not shut down

Originally posted by Jimmy Jessup:<br /> <br /> The 105 chrs. ran great, why does it uses so much gas.<br /> Jim

It was just showing ya some love dude

 

[StriperJim]

Re: Engine would not shut down

 

[rodbolt]

Re: Engine would not shut down

I would love 3 hours on 10 gallons from my 120 jonnyrude. that aint bad fuel economy