mikechip
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- Joined
- Sep 27, 2020
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I have a Poulan Pro with a B&S 1 cylinder OHC 18hp B&S model 31D707 0458E1 that ran fine, until it started surging mid-summer. It always was a "rough start" - meaning, I'd turn the key, it would pause, then crank, then pause, then crank and then eventually start. I replaced the battery and replaced the carb because it was so nasty it couldn't be adjusted, replaced the air filter and after I bolted it all on, it started and ran like a champ. Although - it still wouldn't turn over very easily - it did the whole pause, turn, pause, turn thing, but ultimately it always started.
Now I'm just going to go on ahead and admit that I ride this tractor like I stole it - it's less of a lawn mower, and more of a mule that drags stuff over less than smooth terrain. About 2 months after the carb swap, I'm dragging a de-thatcher over some turf and BOOM, it starts idling like a Harley and ultimately stops running within 60 seconds.
I try to start it and it doesn't even want to crank. If I shoot carb cleaner into to the carb it would turn and chug a bit, then poop out. I pulled the plug - it was fouled like a sailor's mouth. All carbon - no oil in the fouling. Put a brand new spark plug in, it starts and fouls it out in 45 seconds. Same thing - all carbon, no oil.
So I pull the valve cover and the rockers are flapping around like an 80 year old prostitute's boobies. I pull the rockers, replace the push rods (the aluminum rod was bend at about 15°) and I properly gap the valves at .004 inches. Put it all back together - and bang, there is no longer a pause when I turn the key - that motor just turns and turns and turns - but no ignition. I pull the fuel line (gravity fed) and the fuel is flowing like Niagara falls. I check the solenoid on the carb bowl and she's clicking like a champ. I pull the plug wire, jam a screwdriver into the boot and rest it on the motor and when I turn the key, I see spark. Then I pull the plug, put the boot over the plug, rest it on the motor and it is throwing spark in the gap when I crank it. I spray carb cleaner into the carb - no difference, it just turns and turns and turns. I pulled all the crap off the flywheel and ensured that the key was still in place, and it was. I checked the gap on the magneto (coil) and it was fine. If I shoot carb cleaner into the cylinder, it still won't kick when I turn it. However, on two occasions there was a "POP" from the valve cover area.
My thoughts at this time are - the magneto is junk and is throwing irregular voltage/ or has a crack somewhere that is double grounding and maybe the spark at the double-ground cooked off the carb cleaner near the valve cover. I ordered a new coil/magneto and will replace it when it comes in.
But, what else might it be? And am I missing anything? (I do not have the ability at this time to measure the compression.)
Now I'm just going to go on ahead and admit that I ride this tractor like I stole it - it's less of a lawn mower, and more of a mule that drags stuff over less than smooth terrain. About 2 months after the carb swap, I'm dragging a de-thatcher over some turf and BOOM, it starts idling like a Harley and ultimately stops running within 60 seconds.
I try to start it and it doesn't even want to crank. If I shoot carb cleaner into to the carb it would turn and chug a bit, then poop out. I pulled the plug - it was fouled like a sailor's mouth. All carbon - no oil in the fouling. Put a brand new spark plug in, it starts and fouls it out in 45 seconds. Same thing - all carbon, no oil.
So I pull the valve cover and the rockers are flapping around like an 80 year old prostitute's boobies. I pull the rockers, replace the push rods (the aluminum rod was bend at about 15°) and I properly gap the valves at .004 inches. Put it all back together - and bang, there is no longer a pause when I turn the key - that motor just turns and turns and turns - but no ignition. I pull the fuel line (gravity fed) and the fuel is flowing like Niagara falls. I check the solenoid on the carb bowl and she's clicking like a champ. I pull the plug wire, jam a screwdriver into the boot and rest it on the motor and when I turn the key, I see spark. Then I pull the plug, put the boot over the plug, rest it on the motor and it is throwing spark in the gap when I crank it. I spray carb cleaner into the carb - no difference, it just turns and turns and turns. I pulled all the crap off the flywheel and ensured that the key was still in place, and it was. I checked the gap on the magneto (coil) and it was fine. If I shoot carb cleaner into the cylinder, it still won't kick when I turn it. However, on two occasions there was a "POP" from the valve cover area.
My thoughts at this time are - the magneto is junk and is throwing irregular voltage/ or has a crack somewhere that is double grounding and maybe the spark at the double-ground cooked off the carb cleaner near the valve cover. I ordered a new coil/magneto and will replace it when it comes in.
But, what else might it be? And am I missing anything? (I do not have the ability at this time to measure the compression.)
