missfire 71 johnson 50hp

B

BOO BOO

Recruit
Joined
Jul 18, 2001
Messages
2
The #2 cyl will not fire. Has good spark. Compression #1 150 #2 135 It doesnt matter whatrpm its running at it will not fire. i,ve checked the intake reed valves no problem found. Tried switching coils , spraying fuel in carb but nothing seems to make a difference. There seems to be a lot of fuel coming out with the exhaust water. i,ve also tried cuting the fuel off to that carb but still wont hit Any help would be appreciated.
 
A

adrian bick

Seaman
Joined
Feb 28, 2001
Messages
53
Re: missfire 71 johnson 50hp

CRankcase compression ??????. Possibly the bottom seal on the crankshaft is blown.Result no fresh mixture goes into the cylinder.
 
P

Paddling

Seaman
Joined
Mar 29, 2001
Messages
71
Re: missfire 71 johnson 50hp

Hi Boo,<br />Have you tried a new plug? I'd suspect one is defective from your description. How did you determine good spark, with plug out and grounded or with just the wire off? It's rare but I've bought brand new plugs that wouldn't work. Good luck.
 
B

BOO BOO

Recruit
Joined
Jul 18, 2001
Messages
2
Re: missfire 71 johnson 50hp

Their new plugs and i tried switching them no change. The lower plug is real clean and white like no fuel. I went though the carb again 5th time, still won't fire. Adrian if its the lower seal is there a way to check without major teardown ??? thanks for the help i'm getting really frustrated!!!
 
F

Fouled Plug

Ensign
Joined
Jun 29, 2001
Messages
935
Re: missfire 71 johnson 50hp

If you're not getting any spark to the dead cylinder, overhauling the carb won't do you much good. Did you try a different condensor and/or points? I don't really know exactly what's under the flywheel of one of those motors.
 
JB

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: missfire 71 johnson 50hp

What Adrian suggests seems plausible, BOO. It is rare, though, that a blown seal will prevent enough crankcase scavenging to the cylinder to get it to pop. Usually it just doesn't make much power but does run.<br /><br />You stated pretty firmly that it has good spark. How did you determine this? Ignition systems have been known to fool the best of us into thinking they have good spark, but then dont put it into the combustion chamber. <br /><br />Let us know any new developments.<br /><br />Red sky at night. . . . <br />JB
smile.gif
 
N

norman158

Petty Officer 1st Class
Joined
Jun 29, 2001
Messages
329
Re: missfire 71 johnson 50hp

when you pulled the #2 plug was it wet or dry ? did you try the old hand choke methoid to get it to pull fuel
 
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