'57 Johnson Sea Horse 10hp troubles...

[Boatdrinks]

Hey guys...my dad and I are at our wit's end with this engine. We have a '57 Johnson Sea Horse 10hp model QD18. The engine has been rebuilt and has very little time on it. The trouble is it won't run well. We can get it started by choking it (then open choke after started) and it will run...but will start to pop and carry on. It acts like it is running out of fuel but the plugs are wet after it quits. When running, you can't touch the throttle or it will quit. It won't even think about idling either. Every time it quits, the plugs are wet. The funny thing is...it used to run perfect for a couple of hours. Then it started acting up. Nothing has changed...the carb is rebuilt, the fuel pump is rebuilt. We converted it to a single line and put a fuel pump on it. It ran great for several hours when we first started it. We never ran it as a two line enging. One thing that happened...she stopped pumping water. Everything appeared ok...and we were really scratching our heads about it...until dad found the problem. The head gasket was leaking between the cylinders...a little compression into the water jacket was what caused the engine to stop moving water. We solved that one though...and the engine did not get damaged by overheating. Everything appears good...no leaks...everything is fresh...great compression...rebuilt carb and fuel pump...reed valves are ok...but we still seem to have a fuel problem of some sort. No amount of adjusting the needle valves seems to make a difference other than not running at all. Is this a fuel problem? Vaccum problem? Timing problem? Like I said...the plugs are wet after she quits, we have good spark....timing is ok... We've gone through this engine with a fine toothed comb to no avail. We are ready to use it as an anchor...does anybody have any idea where to go now?

 

[cheburashka]

Re: '57 Johnson Sea Horse 10hp troubles...

You'll have to give more detail on how you fixed the head gasket problem. Did you pull the head and inspect? Did you replace the gasket?<br /><br />What kind of fuel pump did you install? Vaccum or electric?<br /><br />I know it has spark at idle, but there's a good chance that the coils are cracked and grounding out once you get to higher revs. That happened to me. I'd recommend replacing the coils points and condensers. It does sound like it's possibly an electric problem.<br /><br />Are you sure the fuel is good?

 

[Xcusme]

Re: '57 Johnson Sea Horse 10hp troubles...

Hmmm, major tip off here...you said "No amount of adjusting the needle valves seems to make a difference other than not running at all." This would indicate a carb problem. Either it's not clean or not sealed to seperate the low speed and high speed circuits. Did you replace/retrofit the float?

 

[Boatdrinks]

Re: '57 Johnson Sea Horse 10hp troubles...

Thanks for the replies guys...the head gasket problem...yes we pulled the head off and noticed the leaking gasket. No damage found to the head or block. We put a new gasket back on and bolted it back up. The fuel pump is vaccum. The carb has been rebuilt and there is a retrofit float (not cork) in place. Where would the leak be if the carb was leaking between high/low circuits? Thanks again guys... The coils look good too. The fuel is fresh...even tried two different tanks...

 

[Paul Moir]

Re: '57 Johnson Sea Horse 10hp troubles...

Did you remove the soft core plug and clean the idle orifaces directly? If not, do you still have the plug?<br /><br />You can compensate for a bad/nonworking fuel pump and leaks in the fuel lines by simply squeezing the primer bulb. If the engine doesn't react to that, then you can pretty well rule out the fuel pump conversion as being the source of your problems.

 

[Boatdrinks]

Re: '57 Johnson Sea Horse 10hp troubles...

Yes to the soft core plug being removed for cleaning and yes to the fuel bulb. It's always hard and doesn't have any affect on running. I don't think it is the fuel pump...

 

[Paul Moir]

Re: '57 Johnson Sea Horse 10hp troubles...

Will both sparks jump 3/8" gap? (I see you said good spark, but I want to make sure it really is).<br /><br />Crankcase compression problems usually cause idle/midrange problems & will give you fits adjusting the carb, but don't severly affect WOT. But you can't WOT correct?<br /><br />Is the armature plate so wobbly it would throw off timing by changing the point's gap? Do you have a flywheel with inspection holes? If so, can you examine the points for contamination?<br /><br />Finally, when you rebuilt the carb, did you change the needle and seat? If so, did you use the little spring that holds the needle to the float? What kind of condition is the float in? Did the thick washer gasket that goes over the high speed jet get replaced?<br /><br />Sorry about the 20 questions!

 

[Boatdrinks]

Re: '57 Johnson Sea Horse 10hp troubles...

Guys...thanks for all the help. FINALLY got her running like a champ... It was a coil wire. Both coils are new...one the old style with cloth insulation on the wire and the other one is a newer style with vinyl insulation on the wire. Well...the old style coil with the cloth insulation was shorting out. Just on a whim...we covered the wire with heat shrink...and voila! Runs good as new. Talk about a long road....but she runs like a champ now! On another note....does anybody know where I can find some mixture adjustment knobs for this enging? It is complete except for these knobs....thanks guys for everything!