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ringram

b10 stalling - fuel problem

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ringram
I have a b-10. Not sure if it's a big 10, bit does have the 10hp B&S motor. I've bypassed the original coil (weak) and installed a 12 volt coil that I had. lots of spark now. Here's the problem. The engine will run great, for about 15 minutes or so. Then it will stall like it's out of fuel. I've removed the fual tank, clean it out, cleaned out the fuel line and installed a new fuel filter. When it stalls I can see fuel in the fuel filter (transparent). The fuel line is rubber and runs down below the carb, filter is at the bottom of the loop. And then the line comes up to the front of the carb. Is it possible that the heat of the muffler and pipe is heating up the carb and/or fuel line and causing a vapour lock? What other problems should I be looking for?

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ringram
I believe so. I'll check it tonight when it stalls again. If the spark is weak, than it could be the coil going bad. If it's strong, than it's definitely fuel. If the spark is good, I'll splash a bit of fuel down the intake of the carb and see if it fires up.

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Scott Salmons
I feel your pain, my B-112 does the exact same thing. I have changed it to coil ignition and went through the carb several times. When it dies you can let it set for a while and it starts right up and will run again for a while then quit!!

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ringram
Believe it or not, I think I've tracked the problem down to the starter/generator and the regulator. First of all, I had an intermittent starting problem. This was due to a shorted starter coil in the starter. I disconnected the wires from the starter/generator, re-charged the battery, and rope started the unit. (takes a few pulls, but it works). I was able to run the unit until the gas ran out. Filled it up, and ran it again. Now the problem is, it will cost me almost $200 to rebuild the starter/generator. Plus, I'll have to re-calibrate the regulator to make sure it's working right. Not sure if I want to continue putting money into this unit.

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debshirl
had smae trouble with my landlord kept thinking it was a fuel problem after i rebuilt engine even installed new carb after talking to a buddy of mine finally found for some reason my points had closed up reset points and regapped plug started up and ran good no problems so far

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MrSteele
I don't think your starter/generator is the problem. Your tractor is not like an automobile, in that the generator does not affect the ignition system in any way. Once the engine is running, the regulator allows the battery to recharge, nothing more. Do you have gas flow when the engine stalls? Having fuel in the filter is not a guarantee that you have flow at that time. Check the flow from the tank. If the filter in the tank is nearly clogged, it will allow gas to pass through, just not enough to run the engine. Clean that first, then try again. And, be certain that the vent in the gas cap is really venting. The engine will pull a vacuum in the tank if it is not, and you will have a no flow situation, again. As for vapor locking because the line is too close to the exhaust. Even that is unlikely, if you have a rubber fuel line. If you think that is happening, try putting a wooden clothespin on the line close to the exhaust. If the clothespin fixes it, it was a vapor lock. Solution..reroute the line.

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HubbardRA
Check the valve clearance. I have seen more than one stop after a few minutes running because of insufficient valve clearance. Valve stems get longer as engine warms up. This is why there is a specified valve clearance. Without sufficient clearance the valve will stop sealing when it heats up.

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ringram
All good stuff, thanks for the replies. Fuel isn't the problem. Gas cap is venting, cleaned tank, new fuel, new fuel filter, cleaned carb and rebuilt. The problem is that the starter coil in the starter unit was shorting out. It was ok when the engine was cold, but as it ran, the coil windings warmed up, and as the windings expanded with the heat, they shorted. Since the generator and starter windings are connected, this caused a short to ground, reducing the voltage. And since I was using a 12V coil for ignition, the spark reduced as the voltage went down. Once the voltage dropped enough, there wasn't enough spark to run the engine. The engine would only run about 20-30 minutes. Once the engine cooled, the coil windings shrunk enough to eliminate the short (or at least reduce it so that there was minimal power loss). This continued until the windings were shot, which is the case now. The starter will not turn over. Now that I have the starter/generator removed, and I charged up the battery, I can pull start the unit, and it will run fine for hours.. I'm sure that once I rebuild/replace the starter generator, all will be fine. I can't say that this is the problem that some other people are experiencing, but it is the problem on this unit.

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