evinrude running on one cylinder

[66evinrude]

well here it goes hi all im new to this forum and new to boating,got my first boat 1965 crestliner mustang with 1966 evinrude 33hp ski-twin as title says its only running on one cylinder,did compression test 110psi both cylinders, both cylinders getting spark, cleaned carb, didnt get to checking points yet,what do you guys think it could be, i have been working on cars,bikes,snowmobiles for 20+ yrs, outboards are new to me but kinda same thanks in advance, also its the top cylinder that dont work

 

[boobie]

Re: evinrude running on one cylinder

Will the spark jump a 1/4" gap on a spark tester?? If it does one other possibilty is a broken reed or something stuck in it.

 

[66evinrude]

Re: evinrude running on one cylinder

i checked the reeds somewhat looked at front of them didnt take off engine was scared to ruin gaskets and they looked good on front didnt know till after i put them back on that there is little finger type things behind them guess i should take em off is that was normally breaks on reeds? no i didnt do spark gap test yet il have to get a tester also does the fuel pump have anything to do my with problem? i heard some get vacuum from cylinder?

 

[boobie]

Re: evinrude running on one cylinder

The reed itself normally breaks so you should be okay. If the fuel pump runs off the top cyl that could also be your prob. It may be leaking fuel into the cyl on the vacuum side of it.

 

[Scubaproh20]

Re: evinrude running on one cylinder

Vacuum cutoff switch is usually the culprit on motors like ours. The old wires crack vacuum lines leak and the cutoff switch can interrupt your spark on one cylinder especially at low speeds even though its designed to slow a runaway motor in neutral or something to that effect. And to check for the fuel pump problem pull the spark plugs one will be wet and black or soaked in oily gas.

 

[66evinrude]

Re: evinrude running on one cylinder

i did pull the plug wires off one at time while engine was running. bottom cylinder is only one working and top cylinder plug was coved with gas/oil

 

[nwcove]

Re: evinrude running on one cylinder

you can make your own plug tester by clipping the ground off a plug that you know is good. eyeball it a 1/4 inch from the electrode.

 

[boobie]

Re: evinrude running on one cylinder

How big a gap will the spark on the top cyl jump??

 

[nwcove]

Re: evinrude running on one cylinder

both top and bottom should jump a 1/4 inch gap, and be nice bright blue.