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Simplicity 725 possibly not getting enough gas?


justelisha

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I had recently posted about my tractor turning over but not starting. Many people suggested cleaning the carburetor. 

Having never done this, I enlisted a friend that was mechanically inclined and helped take it off, clean it (he said it wasnt that dirty), and put it back on.

Unfortunately, it still wouldn't start. My late FIL actually had a spare carb so we put that on and still no luck. However, there was some engine starter in the boxes of parts and whenever we used that the engine would run until it burned off.

We are assuming it's not getting enough fuel because of that. Could our settings be wrong on the carb or is not enough fuel getting into the engine?

Side note: according to my fiancee, the reason we had the engine started is because the neighbor would mow the lawn for her mom and that's how he would get the tractor to start. FIL never used it.

Thanks again.

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Could be one of several things. Engines kind of get addicted to starter fluid, and its use. Folks use it, thinking it is the only way to get the engine running, and use it every time. Thus, the addiction to it. But, there is another problem going on that causes the hard start. You have, if you have the original engine or a similar version, an old cast iron Briggs engine, likely with weak spark, a bad spark plug, a weak magneto, weak condenser, dirty points, improperly spaced points, or a spark going to ground somewhere.

Check the wire going from the switch to the point cover. That cover is below and to the left of the carburetor. There should be 2 wires coming out from the cover. One goes to the switch, the other disappears under the cover of the engine, going to the magneto. Under the cover there is likely a mouse hotel, if the machine sat unused for a few little whiles. Removing the cover is interesting, and the best way is to disconnect the drive shaft going to the rear of the tractor, remove the cover and blow out the mouse motel with hands and compressed air, being sure to blow air through the cooling fins above the flywheel. Now you can check the wires at the mag. Mice like to chew the insulation on the wires. Loss of insulation allows the wires to go to ground. Maybe not all the time, but enough to cause a spark problem. The insulation can be repaired with shrink wrap, but you might want to invest in a new mag, as that was likely the problem that started the use of starter fluid in the first place. I start a lot of engines that have been sitting up, but starter fluid is always a last resort. Last resort..I have to go buy some, as I do not have a can in the shop

Remove the cover over the points and condenser, use emery cloth or similar to polish the points, and be sure to blow the points after polishing, clean of debris left by the polishing. Set the point gap at .020 with a feeler gauge. You can turn the flywheel by hand to open the points before setting them. Having the spark plug out while turning makes the job easier. Check the wire going to the condenser to make sure it is not grounded. That can cause one to pull hair out. I had a clip that grounded from time to time under the cover, and would have never found it had I not attempted repairs in late evening, in low enough light to see the spark flash at the connection. The engine ran most of the time, but would cut out from time to time. I ruled out the carb, as you have, but simply could not find the problem. The connection block under the cover was grounding from time to time. You might want to put a new condenser in it before putting it back together. If there is a Nova module hiding under the cover, you might want to replace it. They do go bad.

A new spark plug is almost a given on old engines. These engines did not have resistor spark plugs, put one in without internal resistance. 

As for the carb settings? Turn the screw at the bottom of the carb out 1 1/2 turns, and the screw at the top on the throat about a turn. That should allow enough fuel to make the engine start and run. You can adjust from there. The engine will run at those settings, but will not run right until final adjustment.

Good luck, and if you have questions, just ask

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The fact that it runs on starter fluid tells me that, like your title implies, it is not getting normal fuel.  Does gas run out of the fuel line when disconnected from the carburetor?  The tank, fuel line fitting or filter could be clogged.  When your friend cleaned the carb, did he clean out the jet?  A used, replacement carb can still have a clogged jet.  But as @MrSteele suggests above, even if it turns out to be a fuel supply problem. you should probably tune up the ignition system.

 

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I took a look at your original post and read B10 Dave's response and I think he hit the nail on the head.....you have to make sure that you got all the passages in the carb, best done with tiny drill bits or stiff but very thin wire..I recently had a similar problem with a 727 and I kept taking off the carb and spraying it and blowing it and putting it in my ultrasonic cleaner and I finally found a passage that I kept missing....once I cleared that it started right up...you can get a new carb for it for about 11 dollars on Amazon, but it is not an exact replacement....also make sure that the tank is clean and change the fuel lines all the way from the tank to the carb, new fuel filter and a shut off valve.

Edited by MARK (LI)
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