1990 johnson 140 caught fire

aquaman88

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Oct 12, 2012
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my engine caught fire the other day in my driveway, i was able to put it out fast, after further inspection the oly suspicious thing I found was what appeared to be some sort of ground wire that was hanging, I have no idea what this is, it looks like some kind sensor that appears to be broken off its base, does anyone know what this part is and could this have cause sprark to start the fire?140.jpgthe wire was coming from the power pack
 

phillnjack2

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Apr 30, 2011
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Re: 1990 johnson 140 caught fire

that is just a temp sender.
Now if you had a fire that means you have something very very wrong going on.
the sender would only have given an earth, and then only if the engine was very hot and would of caused the alrm to go off.
i would say you maybe have a watercooled rectifier (im not sure if you have this on your model) and if so its got over heated and the rectifier is the fire.
the temp sender could just be a coincidence or fell off due to over heating the glue its been held on with !!!!!!
im sure someone here will know if you do have a water cooled rectifier/regulator on that motor.

ive heard some horror stories about the regulator/rectifiers causing flames and fires, something not very good about that.


phill
 

daselbee

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Jan 20, 2009
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2,765
Re: 1990 johnson 140 caught fire

Yup, that is a temp sender, and cannot cause the fire. The engine is also a "water cooled rectifier" model. It is interesting....caught fire in the driveway....I bet he was using the muffs to run it, the muffs introduced air into the top of the block, and the reg/rect fired right up. You guys who don't believe me regarding the use of muffs....here you go.
 

aquaman88

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Oct 12, 2012
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Re: 1990 johnson 140 caught fire

I was not using the muffs, i just fired it up to see if it would start, was only planning on letting it run for 30sec or so but the fire started right after I started it up (within 5 seconds) the engine was cold, the last time it was run was a week before (I had it out on the water for about 30min) my mechanic cleaned the carbs before the 30min ride, I have been having problems at WOT with bogging and tach not reading right, the needle would go to 4000rpm then shut down to 0 (set on 6p) the tach did not reflect any audible change in the motor. the bogging and slowing down happened on 3 separate occasions, i would get up to 30mph WOT, it would bog then only be able to get up to 24mph
 

phillnjack2

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Re: 1990 johnson 140 caught fire

No water at all to start up the engine !!!!!!!!!!!!!!!!!!! well your asking for trouble then.

NEVER NEVER NEVER NEVER, start an outboard engine without water going through the water pump.
Unless the gearbox is off and a pipe shoved up the inlet tube.
the water cooled regulator/rectifier can get hot quick, but it sounds like its been on the way out for a while already.
you might of have a previous water temp problem and not known it, if youve startted it up even for 5 seconds before then
you need a new water pump impellor.
Starting them up dry is a real no no, i do know people who have got away with it,but know hundreds who have not.

youl be needing a impellor even if the engine didnt start but was turning over quick for a 30 seconds. the impellors need to be wet.


phill
 

aquaman88

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Oct 12, 2012
Messages
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Re: 1990 johnson 140 caught fire

i have started it since the fire with the cowling off and on muffs and everything seems ok and a healthy water stream, i do not see any melted wires, any idea of what could have caused spark to start a fire? there was gas in the cowl pan and down the mid section from being stored trimmed all the way up (the engine was trimmed all the way down before I started and the fire)
 

phillnjack2

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Re: 1990 johnson 140 caught fire

petrol vapours rise they dont sink.
any spark could cause a fire.
there is spark going on up in the stator area and tiny sparks you wont see unless its very dark.
for it to be the rectifier area i would say it is the rectifier.
is the rev counter still working ? charging ? etc
just putting a fire out isnt the answer to the problem,you realy need to find it.
i wouldnt even dream of having petrol anywhere near it let alone start it till i find the problem.
you can have a small fire turn into mega fire within split second, if the vapours from the carbs get caught your
gonna get singed eyebrows and a big bill for engine repairs. thats if your lucky.

i would drain the carbs, fill a butt with water, and then let it turn over at night or in the dark and see if i could find the spark.
do not take spark plugs out and leave them out while looking or youl get sparks everywhere.
you need to turn this over just as if starting it up with juice etc.
just dont connect the fuel at all.
if the rev counter isnt working or your not getting full charge the rectifier is bad and needs changing.


where exactly was the fire ? was it comming from outside or inside the unit ?

phill
 

phillnjack2

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Re: 1990 johnson 140 caught fire

Oh and one quick way to get a complete engine fire is wet wd40 and a spark !!!!!
how do i know this ?
singed eyebrows and lips while standing over a car engine i just sprayed with wd40 !!!!!!!!!!!!
 

aquaman88

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Oct 12, 2012
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Re: 1990 johnson 140 caught fire

the fire was down the mid section to the lower unit, the cowling was on the motor, the whole engine had flames around it,i put the fire out with an extinguisher, then hosed off the residue, took off the cowling and the only signs of a fire was on the paint on the outside on the pan and mid section, under the cowling there are no signs, no melted wires, hoses, I am assuming that there were no flames under the cowling because there was no oxygen under there but it does seem odd because there were a lot of flames on the outside of the motor
 

S_Laker

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Jul 13, 2011
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Re: 1990 johnson 140 caught fire

Sounds like the engine flooded a bit and dumped raw fuel/fuel vapor out the exhaust, engine fired and lit it, causing far too much excitement. I did this with an old motorcycle once, kicked and kicked, when the engine fired it shot burning fuel out both mufflers. VERY exciting in a 100 year old frame building. :eek:The flames on the outside of the motor was probably vapor rising and burning off. Glad no one was hurt.
 

out 2 launch

Petty Officer 3rd Class
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Dec 11, 2008
Messages
77
Re: 1990 johnson 140 caught fire

petrol vapours rise they dont sink.
I think with a little research you will find that gasoline vapors are actually heavier than air and have a tendency to sink.
 

tomhath

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Dec 5, 2007
Messages
814
Re: 1990 johnson 140 caught fire

Sounds like the engine flooded a bit and dumped raw fuel/fuel vapor out the exhaust, engine fired and lit it, causing far too much excitement. I did this with an old motorcycle once, kicked and kicked, when the engine fired it shot burning fuel out both mufflers. VERY exciting in a 100 year old frame building. :eek:The flames on the outside of the motor was probably vapor rising and burning off. Glad no one was hurt.

This is why everyone should video things like initial start-ups. You could've been a star on youtube...:D
 

phillnjack2

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Re: 1990 johnson 140 caught fire

well if petrol vapors sink from your fuel you have a big problem .
gasolene fuel lets off vapours and they rise, then they fall when they get mixed with air.
watch the large upward flame from oil rigs and petrol refinerys, ive never seen a dropping flame from them !!!!!!!
you stand over a can of petrol and strike a match and see if the fumes fall or rise shave first to save the smell of burning hair.

anyway somehwere on the engine is a spark or loose connection that causes a spark.
the flame in the mid section is not from exhaust, the exhaust goes outside not down in the mid section and the pan.
far too many bends and places to act like flame traps on a normal stock outboard engine like this one.(my opinion)

i would say that fuel from the carbs when tilted are in the mid section and thats where the vapor has come from
once the spark catches then wallop, off goes the petrol to cause some flames and start burning.
could even be wd40 if youve used that to spray over the engine to keep it from rusting etc.

from the first post i thought you had a fire from the rectifier !!!!!!!! thats why i said water cooled rectifier.

you need to get the fuel out the engine and check it by spiining it over during the night or under cover where its very very dark.
personaly i would do it outside late at night and watch for any sparks anywhere . keep the fire hose ready as well ha ha

you might have a leaky spark plug lead, they do break down and often give off a spark or two.

now down at the bottom of the engine pan should be some small holes, always make sure these are clean so any
spilt fuel of water can escape or this can happen again, but next time could be worse !!!

I always run my engine out of fuel when finnishing up for the day, but even then i still get the odd bit of fuel from the
carbs when tilted up fully.
i do clean it up and dry it off but its easy to forget.

anyway check it in the dark, and watch everywhere for the od spark,if its a electrical leak then performance is going
to be down a bit as well.


phill
 

aquaman88

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Oct 12, 2012
Messages
9
Re: 1990 johnson 140 caught fire

the flames were definitely from the gas that was dumped out of the carbs when the motor was trimmed all the way up, then i guess when i trimmed down the gas poured down the mid section, then lower unit, good idea with turning over in the dark to look for spark
 
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