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1979 Evinrude 115 hp wonbt fire at low speed on one cylinder

S

sherman

New member
I have run compression check

I have run compression check (120 on all cyl.). I switched coils and powerpack from left to right without any change. The number four cylinder still
does not fire at idle or until I get to about 2500 rpm. I rebuilt the carbs still no change. I did the 3/8 inch spark gap test all ok. I pulled the exhaust cover and every thing looked ok. Now I have started yelling at the dog.

Please help with any ideas of what to do next.
 
quick look in omc manual seem

quick look in omc manual seems to show fuel pump on that cylinder.i had leaky diaphram once thatloaded up that cylinder and it would only start firing at 2000-2500rpm. just a thought.
 
quick look in omc manual seem

quick look in omc manual seems to show fuel pump on that cylinder.i had leaky diaphram once that loaded up that cylinder and it would only start firing at 2000-2500rpm. just a thought.
 
" Sherman;Check the fuel pump,

" Sherman;Check the fuel pump,check the reed valves,look for leaks between the 2 halves of the crankcase.Zeke "
 
Thanks for the ideas. How ab

Thanks for the ideas. How about the bottom seal on the crank since this is the bottom cylinder.

Sherm
 
Maybe something is stuck in a

Maybe something is stuck in a reed valve like a screw or even some mouse poop(they do build nests in intakes). How about a defective sparkplug.Pull the plugs and pull the motor over evenly and listen for the crancase compression.Pull the bypass covers and inspect the pistons and rings.
 
Thanks -- I pulled the exhaus

Thanks -- I pulled the exhaust cover and from that side the rings look ok. There is some blow-by past the rings but I could only run a leak down test at 75 psi and I got about a 10% leak down. When I had the carbs off for rebuild I looked at the reeds from that side and things looked ok.
 
Thanks
I got the thing fix

Thanks
I got the thing fixed But I really don't know why. I think it was a kinked hose to the lower carb. I did clean the carb. again and when I put it back together it worked.

Thanks for the help.

Sherm
 
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