Johnson 120HP Motor bogs or jumps or dies with throtle applied

[CatfishJim]

I have a 120 1987 that runs fine for about 20 mins and then trouble starts after a long idle or shutting the motor off. What happens is after a restart it will idle fine but with throtle applied sometime during the planing the motor will seriously bog or die like the switch was just turned off. after a restart it idles real rough like only two cylinders are firing jerks to one side if the throtle bar is lifted the motor pulls out of its slump but still will not plane out.<br /> No change when pump the fuel bulb. Its not jumping out of gear. Runs fine when cool<br />POWER PAC?<br />Stator?<br />Coils?<br />or fuel?runs fine when cool!<br />Let me know guys<br /><br />------------------<br />Everyday a catfish is just around the way.<br />Maybe today a big one<br />will take my worm away

 

[CatfishJim]

Re: Johnson 120HP Motor bogs or jumps or dies with throtle applied

forgot to say that spark plugs have been changed plus new impeller this is a new motor and im gonna be in the dawg house if i dont fix it for cheap<br /><br />------------------<br />Everyday a catfish is just around the way.<br />Maybe today a big one<br />will take my worm away

 

[kenthrussell]

Re: Johnson 120HP Motor bogs or jumps or dies with throtle applied

hi recently i had a problem with my 200hp merc,the problem was dirt in the carbs, after about 15 minutes of idling the problem would show up and the needles in the floats would stick and not close off causing a flood.if you can run the motor with the attenuator off the front of the carbs and watch for gas coming out of the front of the carbs....that was my problem but like i said it wouldn't show up for about 15 minutes of running,took carbs off and cleaned them up with carb cleaner and installed a good inline filter,never happened again.hope this cures your problem

 

[CatfishJim1]

Re: Johnson 120HP Motor bogs or jumps or dies with throtle applied

Anyone Else?<br /><br />------------------<br />Everyday a Catfish is just around the way maybe tomorrow a big one will take my worm away

 

[Liam]

Re: Johnson 120HP Motor bogs or jumps or dies with throtle applied

Catfish, I have the exact same problem with my 60 HP Johnson. I changed the fule, fuel line, filter, sparkplugs, plugwires. Sprayed out the carbs with carb cleaner. Pulled out the rest of what little hair I had and finally I have an appointment to see the outboard magician of Fairfield County, CT!! I'll let you know what it was by Wednesday or Thursday.<br /><br />Good Luck<br /><br />Liam

 

[CatfishJim1]

Re: Johnson 120HP Motor bogs or jumps or dies with throtle applied

Anyone else???<br /><br />------------------<br />Everyday a Catfish is just around the way maybe tomorrow a big one will take my worm away

 

[StringBox]

Re: Johnson 120HP Motor bogs or jumps or dies with throtle applied

Liam - I am having exactly the same trouble with my 1971 Johnson and would very much like to know how it turns out. Please post when you get it running.<br />Thanks!

 

[clanton]

Re: Johnson 120HP Motor bogs or jumps or dies with throtle applied

Check the spark after engine is up to operating temp.

 

[StringBox]

Re: Johnson 120HP Motor bogs or jumps or dies with throtle applied

Thought I would follow up on what I found with my motor for any of you that are interested. <br />First I double checked my carbs to make sure the needle valves were not sticking and the floats were<br />adjusted correctly. <br />Next, I took a look at the points. Big pain in the butt getting the fly wheel off, but persistance paid off and I managed to get it off without doing damage to anything. The points were a little dirty but not bad. I cleaned them with some fine sand paper and set them both to .010. Not wanting to repeat the procedure, I double checked everything before reassembly. <br />Although it did sound a bit better after cleaning the points, I still had the same problem.<br />Next I checked the manual for setting the low speed idle on the carbs and there I believe I found the culprit. I adjusted them with the motor running with a water hose and muffs. Motor sounded great! Off to the River we went. Unfortunaly, the engine would idle great and I could run it up in neutral fine, but when I engaged forward and gave it throttle it died immediatly. I let the engine warm up a bit and then made a run for it. Had to be towed back to the landing. <br />A little more fiddleing with the idle adjustment and things improved dramatically. I still need to tweak it a bit, but basically, I bottomed out the adjustment screws on all three carbs, then opened them all up about 3/4 of a turn.<br />Motor ran out to about 5500 rpm and pushed my little 15 foot 1971 Caravel Bow rider about 40MPH with three adults on board. <br />Hope this helps someone, good luck.