Sudden start problem

[motomike]

Hi all. Decided to grease the spindles on my '99 Murray with the 17hp BS Twin II. Had the front end raised with the Mojack. After I put it back on the ground the mower refuses to run. It will start but not build speed and seems to choke down and quit. Saw puffs of black smoke out the exhaust.

Tried to start with the choke and no choke, doesn't seem to make any difference. Sprayed a little carb cleaner down the carb throat and it briefly seemed like it was going to spin up but quit again. Why would all of a sudden seem to be not getting gas after running perfect beforehand?

I pushed it back into the shed and put the battery tender on it overnight. I might try changing plugs and fuel filter on it today if I don't hear anything otherwise. Thanks for any advice.

 

[Auto Doc's]

Sounds like you may have had a little water/trash fuel gathered in the fuel tank. Most of the time this little bit of water/trash fuel does not move around. When you jacked it up, the water moved toward the tank fuel outlet.

A little trash from an open fuel can also be the issue. Fuel cans are seldom checked or cleaned.

I recommend you drain all the fuel out that you can, then blow the tank dry if possible, or let the machine sit in the sun for a couple of days with the fuel cap off.

Humidity in the air collects in fuel tanks over time (years) This humidity eventually forms droplets. It happens to gas powered machines and gas cans that are left sitting for long period of time. It is best to keep you fuel tank full and that will minimize the problem.

When you refill the tank, only use new fuel from the gas station. Non-Ethanol is best if you can get it. If not use the mid-grade selection I do not recommend the lowest price budget fuel because problems will keep happening.

 

[motomike]

Thanks for the reply. I kinda ruled out bad gas since the last gas I put in was only about 2 mos max old and I use stabilizer in my over winter fuel since the equipment is run less. I always buy 87 non ethanol for my small engines also, have for years. And I had run the tank on the Murray completely empty not that long ago.

That being said I'm certainly no expert in the field. So, I've drained the tank, blown out all the fuel lines to the carb and will reassemble with a new filter I have on hand. I also already picked up fresh gas this morning. The mower is sitting in the sun now drying out before reassembly. I'll let everyone know if this works.

 

[motomike]

Cleaned tank, (it looked spotless beforehand), blew out fuel lines to carb, new fuel filter, fresh gas. Still won't run. Got a pair of new plugs and it tried to run a little better but still no go.

Something must have gotten upset inside the carb when I had the nose up in the air? It didn't have much gas in the tank when I raised the front end, could a big air bubble have gotten in the line somehow. I did not try to restart it until it was flat on the ground again. The plugs were dry when I removed them. Looking down the throat of the carb, it looked super clean. It's a replacement carb I installed 8 yrs ago,

 

[Auto Doc's]

Is your engine the opposed twin cylinder or the V-twin? I just want to clarify.

The opposed twin cylinder version had a pulse pump diaphragm built onto them that would fail without warning like this.

The diaphragm is pretty simple to replace.

 

[motomike]

My numbers are 42E707, 2631E1, 9903155A if that helps identify. I know it as a Twin II.

 

[Auto Doc's]

Those number show to be an opposed V-twin. The trouble is likely in the carburetor fuel pump, or your fuel filter shifted debris inside when you lifted it up in the front and it created a blockage.

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