Stalls Under Load

[tippy777]

Have an 80's model Nissan 18hp electric start which we've been putting back together. Ran great for a while the started experiencing problems like misses, coughing, etc. Changed out the coil as the old one was nasty and that seemed to work ok until the other night. Started it up ok but when I put it into gear, died. Started it up several more times and it died each time as soon as I tried to advance the throttle. Kept doing that all the way to ramp, we had to use the trolling motor to get there. Now it seems like it's not getting any spark at all? This is an older model, probably in the late 90's.

 

[pvanv]

Verify whether you have spark. It sounds like a fuel issue.

 

[Sea Rider]

When wanting to stall prime bulb repetedly, if motors springs back to life defintely it's a fuel related issue : tank's air vent remained at closed position, internal fuel tank is dirty, small internal filter clogged with debris, fuel pump's diaphragams hardened, severely balooned, main fuel filter dirty, clogged, carb with dirty issues, bad spark plugs, worn fuel connectors o'rings sucking air and motor missing, bogging down, stalling at 1/2 to full throttle at speed..

Having spark on both plugs doesn't say much, any electrical component could shortage itself when overheats and miss, work OK when cooled down to miss again repeateadly. Worse nightmare to troubleshoot right unless having all the electricals to swap and test. Troubleshooting cold components with a tester won't say much either if components overheats and shorts...

Be aware that motor is a 39 year oldie, rubber parts and electrical components doesn't last that loooong LOL!!

Happy Boating

 

[km1125]

What is the actual model? I read "and 80's model" and then at the end "This is an older model, probably in the late 90's", so now I'm confused if it's a 2 stoke or 4 stroke.

 

[Sea Rider]

Should be an old 2 strokes motor, post pics of the interior for model clarification or check sticker on lateral pan side if still having one and post current model.

Happy Boating