runaway 150 evinrude not good

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dezee

Cadet
Joined
Apr 28, 2007
Messages
17
first startup of season boot on good stream of water running about 1000 to 1500 rpm motor runs away to full thottle by itself . shut ignition still running shut batt switch still running pull all six plug wires still running for about 30 seconds. motor overheats and dies. this is a first for me ; any ideas on this one? thanks
 
Scaaty

Scaaty

Vice Admiral
Joined
May 31, 2004
Messages
5,180
Re: runaway 150 evinrude not good

Sure ya didn't touch/goose the throttle, which is a no-no..
 
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steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: runaway 150 evinrude not good

Very scary, something got hot enough inside, probably carbon, to ignite fuel next time eliminate fuel supply.
 
kenmyfam

kenmyfam

Supreme Mariner
Joined
Aug 10, 2006
Messages
14,385
Re: runaway 150 evinrude not good

Runs for 30 seconds without spark. Thats a ton of heat to keep igniting the fuel. Major carbon build up is my best guess. Happened on a 2 stroke motorcycle I bought years ago that i got "dirt cheap" as it would not run properly. Rode it home, it ran for a good while after switching off, gave it a full decarb from the heads to the exhaust baffle and it ran like a charm. (Suzuki GT 250) if anyone remembers them 1975 vintage
 
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seahorse5

Rear Admiral
Joined
Jan 24, 2002
Messages
4,698
Re: runaway 150 evinrude not good

dezee said:
first startup of season boot on good stream of water running about 1000 to 1500 rpm motor runs away to full thottle by itself .
Click to expand...


What is the model number as there are a number of different designed 150's?

If it is a FICHT 150, then the fuel pump diaphragm may be leaking into the crankcase.

If it is a 60? engine, then the OIS sensor, electric eye, may have gone crazy.

Another possibility is corrosion on the throttle shafts and one sticking open a ways if you move the throttle lever.

First off, remove the air box and inspect each of the throttle plates to see that they close and open together and that the spark advance linkage is not sticking.

good luck
 
tashasdaddy

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: runaway 150 evinrude not good

remove the plugs, and check compression before you do anything. know what you have to work with. could have blown head,exhaust gaskets, warped heads.etc. then find the cause. boy, what a horrible post for only your second. Welcome to i boats.
 
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throwback2332

Petty Officer 3rd Class
Joined
Apr 22, 2007
Messages
76
Re: runaway 150 evinrude not good

Hey, i just swapped carbs and primer choke from a 1986 150 xp evinrude, to a 1977 175 evinrude. It hasn't been cranked in a while. When I first got it cranked it ran off like you described. I sprayed carb cleaner in the air cleaner and kept push the key in to choke it. Know it idles decent will go out tomorrow and do a tune up. Scared me too.
 
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