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Points Arcing???


stevenj

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Today I tried starting my GTH-L with the KT-17II but it wouldn't start. Checked to see if the plugs were firing and they weren't. Pulled the points cover and turned the engine over until the points closed. There was no continuity across the points so I ran a points file across the contacts a couple of times and then cleaned the contacts by dragging a business card across them. Then I had continuity. Checked for spark at the plugs and now they were firing. Great, I thought, but it still wouldn't start. I dribbled fuel into the carb and it fired right up and would run as long as I kept dripping fuel into the carb intake. Now for the question. When it was sort of running I noticed a blue arc coming from the contacts of the points. Never having looked at the points when the engine was running, I'm not sure if this is normal or not. Is it normal or is there something wrong? Now I've got the carb off and disassembled and cleaned. Hopefully, tomorrow I can find a carb kit and get it back together.
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Ronald Hribar
Check the fuel pump to make sure it is delivering gas before you put Carb back on. Do you have fuel shutoff on gas line. I do, seldom use it however, once in a while i forget that i did shut it off.
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Although it is usually OK to squirt some fuel into the carb and then turn the engine over to see if it will start. It is never advisable to pour or drip fuel into a carb while the engine is running. You already know the engine is not right, so there is a good chance it will backfire through the carb.. What ever container you are using to pour from can explode, and if it does it can ruin your entire day. I have seen two guys severely burned doing just this on a cold Michigan morning.
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A little arc is normal. However the arcing is what brns the points up. If it goes on badly for awhile it will ruin the points. I'd suspect a bad condenser and go ahead and change it. A bad condenser will also cause the timeing to be off a little and that may amplify other small problems like carb problems.
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It is normal for the points to have a crisp blue arc across them. In fact this tells you that they are working correctly. If points are burning much more that they should (on a magneto system) then you should replace the condenser. The condenser neutralizes the arc to prevent particle migration from one contact to the other that causes a hole to develop in one contact and a buildup on the other. At one time many years ago a friend developed a circuit to measure the specific capacitance (condenser) needed for an ignition system. Did that on one of my vehicles and got 28,000 miles before having to do anything to the points. Much better than the normal 3000 that was the standard at that time. Wish I had one of those gismos to use on my tractors. Other problem would be finding a condenser with the exact capacitance that is needed. There is a fairly large deviation on the factory condensers. Sounds like your real problem is in the fuel system. Hopefully rebuilding the carb will fix it. Also check the filter and flow through the fuel line. If your engine has one of those electric shutoff valves, check it also. I've had more problems with lines and filters being plugged than I have ever had with carbs. I normally don't rebuild a carb till I know what the problem is. It is always something that is either plugged up or leaking. If a jet is plugged, the rebuild kit may not fix it.
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Thanks for all the comments. The points had a crisp blue arc across them so I won't worry about the points for the near term. I'll probably install new ones once spring is here. Pulling the carb was my last resort. I had already ruled out the obvious. Had spark, had fuel, had fuel delivery, engine could be made to run using fuel dumped into the engine. The only thing left was the carb. I had pulled the fuel tank and cleaned it out, and installed new fuel line with a new shut off. Also installed a new fuel pump. Pulled the line from the carb and cranked the engine and confirmed that the fuel pump was pumping. I'm well aware of the dangers of dumping fuel down the carb while it is running. I was using a small squeeze bulb with some gas in it. After pulling the carb, the float bowl had fuel in it. There was some grit in the fuel bowl, the main jet needle and passages were corroded, and some of the passages appeared partially blocked. Gave the carb a thorough cleaning with carb cleaner and made sure all the passage ways are clean. Picked up a carb kit and main jet needle today and hopefully I'll put it back together tommorrow. Who knows, this tractor might even run again. I really dislike buying used equipment, because I'm not satisfied until I totally go through all the systems to make certain that they are in tip-top condition.
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