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Discussion Starter #1 (Edited)
Hi,

I am looking for some help on a sudden loss of power in my lawn tractor.

I have a 1997 Mastercraft/Canadian Tire tractor made by MTD. It has a 14.5HP Briggs&Stratton engine. I used it three or four times this year, but each time had trouble getting it going. It had a dead battery, which I had to put on the charger each time to get it going. It felt like the engine was having trouble turning over, and the batter was not putting out enough. I had better luck starting it by removing the air filter first. It was clear that it needed a new air filter, as the old one was quite clogged. But, it basically cut the grass just fine once it was going. I made a mental note to replace the air filter, battery, etc....

This past Sunday I went through the routine of getting it going and began cutting the grass. After about three minutes the revs dropped noticably and the enging lost most of its power. It did not stall, but it was clear that something was wrong.

I have now since replaced the battery, the air filter, the fuel filter, the spark plug, and changed the oil. It is now easier to start, but the engine still does not want to turn over easily, even with the new battery. However, I am not getting the power (or the revs) out of the engine that I was -- even last week.

I had a look at the carb. On the bottom of the carb is a solenoid with two lead wires connected. With the tractor running on "full" (which seems like about half the revs it should have), if I remove the lead wires from the solenoid, the revs jump up to what seems like almost normal. This lasts for about 5 seconds, and then the engine stalls. If I play with the wires while the unit is running, but disconnecting and connecting again, I can get the revs to go up when temporarily disconnecting them, but the revs always go down again when I connect the wires to the solenoid.

SO... Do I clean the carb (probably couldn't hurt), or go out an buy a replacement solenoid? How difficult is it to replace the solenoid? Is this a do-it-yourself job, or do I need to take it in to the shop? I already have the carb removed from the engine block.

Thanks!!

Erik
 

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Sounds like you need a new Anti Fire Solenoid (the one on the bottom of the carb). I would also clean all the holes in the bottom of the carb while you have the bowl off and also clean or replace the main needle valve. It is not hard to get the bowl off, I used a pair of channel locks and rotated the bowl to the left to loosen it, then finished by hand. The solenoid is not hard to replace. I have a B&S 14.5hp OHV also, on an MTD "Yard Machines" mower.
 

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if you remove the wires from that solenoid, it should shut off, when that gets power it pulls the solenoid back into the housing so fuel can go through your main jet, with no power, main jet blocked. Shut everything off, put your hand on the solenoid and turn the key on and off, can you feel it clicking?

Might just be dirty, I'd try cleaning it first, seems like you might have more dirt issues than solenoid problems, I think if you drop the bowl on the carb you'll find some garbage in there.
 

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"if I remove the lead wires from the solenoid, the revs jump up to what seems like almost normal. This lasts for about 5 seconds, and then the engine stalls."

This sounds to me like you are running very, very rich and when you disconnect the solenoid shutting off the gas, it leans out for a few seconds. I doubt the solenoid is at fault. I would remove the carb float bowl and see if the float is working, leaking perhaps.

"It felt like the engine was having trouble turning over, and the batter was not putting out enough. "

Typically this is caused by the valves needing adjusted. I have detailed instructions for adjustment at address below, put in proper format, will be off line for several days after tomorrow evening.

Walt Conner
wconner5 at verizon dot net
 
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