9.5 runs weak, then dies

G

gtodd

Cadet
Joined
May 23, 2009
Messages
12
1972 Johnson 9.5hp 9R72 with full throttle only one cylinder firing, then after awhile other cyl coughs and eventually kicks in. Now we're going. Still only around 80%, but moving, until it slows and slows and finally dies. Carburetion?
 
M

Monte1961

Lieutenant Junior Grade
Joined
May 8, 2011
Messages
1,180
Re: 9.5 runs weak, then dies

First things first. 1, did you check compression? What are the #s? 2nd, Have you checked spark with spark tester? 3rd, When was the last time carb was overhauled? If it has been more than a year, Overhaul carb with new carb kit. Check the first 3 things and post yer results!
 
G

gtodd

Cadet
Joined
May 23, 2009
Messages
12
Re: 9.5 runs weak, then dies

Thanks for the reply Monte1961. What would be considered good compression numbers or at least acceptable?
 
R

Rick.

Captain
Joined
Jul 30, 2006
Messages
3,740
Re: 9.5 runs weak, then dies

"Good" would be anything over 90 and within 10% of each other. Acceptable (IMO) would be anything over 60 and within 10% of one another. Pull both plugs before starting the test. Certainly agree with Monte1961 and would add the 9.5's are notorious for leaking exhaust into the cowl. Your symptoms point in that direction also. Best of luck. Rick.
 
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