1979 115 hp Evinrude one cyl won't fire at low speed

[Sherman]

The number four cylinder will not fire until I get to approx. 3500 rpm. I have interchanged the power packs and coils but the problem remains on this cylinder. I rebuilt the carbs but still no change. Compression is 120 psi on all four cylinders. I have removed the exhaust cover and see not problems with rings etc. I did the 3/8" spark gap test and all four are ok. Now What!<br />If I had a dog he would be in trouble. Please help!

 

[Walker]

Re: 1979 115 hp Evinrude one cyl won't fire at low speed

I can think of several possibilities. Dirty carburator (Idle circuit and midrange jets), lower crankshaft seal leak. Seeing as the cylinder picks up at higher RPM's my guess would be the carburator. What does the spark plug look like from the #4.

 

[Sherman]

Re: 1979 115 hp Evinrude one cyl won't fire at low speed

This spark plug is more black than the others but not fouled.<br /><br />Thanks Sherm

 

[Sherman]

Re: 1979 115 hp Evinrude one cyl won't fire at low speed

Thanks <br />I have this problem fixed. It was a kinked fuel hose going to the lower carb.