[oldiron1]

Hi Guys, Hoping for some input and guidance.

I just brought home a 1969 JD 112 with the Tecumseh engine with Solid State Ignition. The model of the engine is labeled SBH-187.

I noticed the gas smelled old so I drained and refilled with fresh fuel. It immediately fires when on idle and will run for a couple of seconds. It won't fire at all with the throttle up. (I will say that for those couple of seconds, the engine sounds very good.) When I go to immediately restart it, it won't fire but if I let it sit for a minute, it will fire on idle again and run for another second or two. Initially thinking it was fuel related, I replaced the fuel filter, line and wend through the carb and was frustrated last night when it did the same thing.

Assuming now that it's not a fuel problem, I put my spark tester between the wire and plug and while I get consistent spark turning it over, it appears weak to me. I feel like when I initially crank the engine over, it's bright and dims a bit after a few revolutions. Does that sound consistent based off what I'm experiencing with it only firing on idle for a few seconds? Please forgive my ignorance, but this engine doesn't have traditional points/condenser, correct? I'm afraid I might have a failing coil. Any thoughts?

Thanks in advance for any input or guidance, Rob

 

[tommyhawk]

That Solid State module was prone to failure early on. However, if you have consistent spark, I would still be looking at the fuel supply. How did you clean the carburetor? After seating the main jet screw, how many turns out did you set it? Is the throttle shaft and the carb bore that it rotates in worn badly? Are the mounting bolts tight? Is the mounting flange flat and sealing with the proper gaskets? Is the heat shield still between the block and carb base?
The Walbro LME carb may not be the best in the world, but if it is clean internally, sealed to the block, in good condition, and set properly, it will run like a champ.
Old gas, plus the corrosion from water, makes all small engine carbs hard to get completely clean. Parts are getting hard to come by too, but I believe there are carb kits shown on Amazon, and possibly an after market carb.
Also, inspect around the head as much as you can see and look for a leaking or blown head gasket.
Good luck and let us know what you find.

tommyhawk