'93 2-stroke 15hp won't start, has run recently.

[DangOlPossum]

Motor came with a jon boat I bought, its a '93 15 HP pull start with Serial Number Beginning 0T76.

I got the motor started in my garage the day I brought it home, about a month ago. Idled great and shifted into forward easily. Using 10%Eth gas with the proper mixture and a gas tank that stays on my outboard stand.

Put the motor back on the boat last week and went to the lake. Motor started on 3rd pull and idled for a few seconds then died. It hasn't started since. Different gas tank, same fuel mixture, same fuel line as used on the outboard stand.

Compression is 75-80 psi on both cylinders.
New spark plugs, correct for engine, both have good spark.
Checked fuel filter and lines, no blockages or major debris present anywhere.
Replaced fuel line with new ethanol resistant lining just because, old hose lining was in good shape.
Fuel pump gaskets are intact.

Spraying starter fluid into the spark plug holes and the carb has had no effect. Engine doesn't sputter or kick at all.

I'm not 100% sure fuel is making it into the cylinders.

I'm starting to suspect debris/water/varnish either somewhere in the carb or on the reed valves.

I can tell a previous owner has spent time inside this engine. I can see liquid gasket.

Today I'm going to rebuild the carb and replace gaskets in fuel pump and between carb/block. I'm also going to get ethanol free gas and clean out old fuel tanks.

If the carb rebuild doesn't solve it, where would you look next?

Any other tests you would do?

 

[flyingscott]

What about spark? Have you checked? Look at the carb base gasket make sure it is the correct one. And make sure it is on correctly, all holes must line up.

 

[DangOlPossum]

What about spark? Have you checked? Look at the carb base gasket make sure it is the correct one. And make sure it is on correctly, all holes must line up.

Good spark on both plugs, carb base gasket looks to be the right one, lines up correctly and was in place when the motor ran well.

 

[racerone]

Spraying starter fluid into the engine should make it bark like a pitbull !-----Tell us more.----You did have water hooked up to prevent damage to the pump ?--How did you run it ?-----Full throttle with an abrupt shutdown ?-----I would pull the flywheel and check the key.-----Very little effort and no $$$ spent for that inspection.

 

[flyingscott]

What is your starting procedure?

 

[DangOlPossum]

What is your starting procedure?

Hook up gas line
Pump bulb until firm
Pull choke/priming knob
Connect kill switch
Pull starter handle

 

[DangOlPossum]

Spraying starter fluid into the engine should make it bark like a pitbull !-----Tell us more.----You did have water hooked up to prevent damage to the pump ?--How did you run it ?-----Full throttle with an abrupt shutdown ?-----I would pull the flywheel and check the key.-----Very little effort and no $$$ spent for that inspection.

Yes I had the lower unit sitting in a tub.

This motor has a thermostat. Once it warmed up it was spitting water just fine in the garage. It didn’t run long enough at the lake to check for water coming out.

In the garage it idled it with no trouble and revved the engine with no issues. Shut it down by pulling kill switch. Started it again on the 2nd pull later that day. Same shut down.

At the lake it started on 3rd pull and idled for a few seconds before sputtering out. Didn’t even have time to throttle or push the choke/prime knob back in.

 

[flyingscott]

Is this a tiller or remote model?

 

[DangOlPossum]

Is this a tiller or remote model?

Tiller

 

[DangOlPossum]

Spraying starter fluid into the engine should make it bark like a pitbull !-----Tell us more.----You did have water hooked up to prevent damage to the pump ?--How did you run it ?-----Full throttle with an abrupt shutdown ?-----I would pull the flywheel and check the key.-----Very little effort and no $$$ spent for that inspection.

Only money spent would be for a strap wrench and flywheel pulled, haha. But there’s a harbor freight down the street.

If the key is sheared off, it wouldn’t turn the crank or advance the motor, correct? I ask because I can confirm that the pistons are moving.

 

[DangOlPossum]

If I pull the spark plugs and cover the hole with my hand, I can feel the puffs of air as I pull the starter.

If I have good spark then this must mean that I’m not getting fuel to the cylinders, right?

But even when I spray starter fluid into the spark plug holes it doesn’t try to run, so does that mean my spark could be weak?

I could take a short video of spark plugs next to the block if that would help.

 

[flyingscott]

Turn the knob all the way to the right after you prime it. That will give you a high idle to warm it up.

 

[DangOlPossum]

Turn the knob all the way to the right after you prime it. That will give you a high idle to warm it up.

Yep, that’s what i did when it ran. If I could just get it to run that’s what I would do haha

 

[DangOlPossum]

Signs of life!

Motor has no carb installed right now, I disconnected the fuel line that runs from the bottom of the carb and T’s off to either cylinder. After removing the fuel line, I slowly pulled the starter cable and was surprised to see fuel/air spurting OUT of the brass nipple on the lower cylinder.

I thought fuel should flow IN to that nipple, surely.

I gave the starter a stronger tug and the motor actually fired up and surged until I hit the kill switch.

Does fuel coming out of the brass nipple (in photo) indicate a valve operating incorrectly?

 

[racerone]

That nipple might be part of the oil recirculation system.

 

[QBhoy]

Hi..if your gauge is correct, you have low compression. I wouldn't ever put starter fluid into a 2 stroke either. But even with the low compression...a carb clean should help a little.

 

[DangOlPossum]

Rebuilt the carb, opened the throttle manually and she fires up and idles well.

People familiar with the motor say they need more throttle as they get older. I'll likely have to rig a length of wire through a hole in the cowl so i can manually open the throttle for cold starts.

 

[racerone]

Those folks are guessing.-----If it takes more throttle now there is something wrong.

 

[flyingscott]

Are all the parts for the primer knob in good condition? They do like to break and will not pull the stator forward.

 

[QBhoy]

Rebuilt the carb, opened the throttle manually and she fires up and idles well.

People familiar with the motor say they need more throttle as they get older. I'll likely have to rig a length of wire through a hole in the cowl so i can manually open the throttle for cold starts.

You’re kind of right. Many people in modern times maybe forget how to start a old 2 stroke. I can mention that with all my old 2 Stoke Yamaha lovelies… and literally just this evening being out all night with a 40hp yam 2/ boat of a pals…every single one of them start best with one particular method…
Choke on….pull once or twice at most…she will give a kick or start….if she starts…choke off and some revs…if she doesn’t…choke off and some revs….there just isn’t anything more reliable for starting, than an old merc or yam 2 stroke….as long as they haven’t been ridiculously miss treated previously