B&S 19.5 hp Lawn tractor?

[John(videodoc)]

I got a lawn mower from an uncle when he died a couple of years ago, well with my cubs, i never had to use it. thought i would get Teya on it thtis year to start mowing. Well it ran good for about 15 minutes and then nothing. So in following the three rules, 1.fire, 2, fuel, 3. air this is what i have done. basically took it down to the flywheel. looking for the points still aint found them. traced the plug wires back to a magnetic coil by the flywheel, cleaned that up. i replaced the fuel line and filter and made sure there is fuel. air cleaner is disassembled currently so that cant be it. it will crank all day long but not turn over. has fuel, has air, plugs are clean. cant find points. any ideas?

[junkman1946]

Briggs has been using Breakerless ignition for about 25 yrs now. So unless its very old it probably does not have points. I am assuming the 19.5 h.p. is a "thumper" that is, a horizontally opposed 2 cylinder. I have never seen one with points. To simplify it greatly, the spark originates from the rotating flywheel to the coil mounted on the block close to the flywheel. Crocus-cloth the side of the flywheel to insure magnetic flow. The coil and flywheel should NOT touch. Also check for a broken flywheel "key". A key that looks even slightly distorted will throw the timing off enough so it wont start. Finally; if you find a wire leading to the bottom of the float bowl of the carb. That is a fuel shutoof solenoid, very prone to failure in Briggs.

[John(videodoc)]

Briggs has been using Breakerless ignition for about 25 yrs now. So unless its very old it probably does not have points. I am assuming the 19.5 h.p. is a "thumper" that is, a horizontally opposed 2 cylinder. I have never seen one with points. To simplify it greatly, the spark originates from the rotating flywheel to the coil mounted on the block close to the flywheel. Crocus-cloth the side of the flywheel to insure magnetic flow. The coil and flywheel should NOT touch. Also check for a broken flywheel "key". A key that looks even slightly distorted will throw the timing off enough so it wont start. Finally; if you find a wire leading to the bottom of the float bowl of the carb. That is a fuel shutoof solenoid, very prone to failure in Briggs.

i see the magnet. cleaned the flywheel and magnet. will readjust so they no touch. where would this key be? i think i know about the wire you are talking about. does that shut off solenoid replacable. how do you tell if its bad?

[John *.?-!.* cub owner]

The key is in the crankshaft where it passes through the flywheel. The solenoid is on the bottom of the carburetor, and is replaceable.

[John(videodoc)]

by "key" are we talking about them half moon metal bits, sometimes just a rectangle within a shaft to keep things lined up. ? (Just making sure we are talking about the same thing)

[Bill E Bob]

by "key" are we talking about them half moon metal bits, sometimes just a rectangle within a shaft to keep things lined up. ? (Just making sure we are talking about the same thing)

Yuppers! The key is usually a soft metal (read aluminum) that hopefully will shear if the engine is
suddenly stopped. You especially find them in the push mowers with the blade attached directly to the crankshaft (attempt to keep the crankshaft from bending) AND yes, they can distort and drive you batty trying to figure out why the engine won't fire (Don't ask me how I know )

[junkman1946]

Heres a real stupid question. But Did you actually verify that you have a "No spark" condition? You can purchase a cheap spark tester at a parts store(less than $!0.) you put it right in line on the plug wire- crank the engine.Briggs ignition systems were among the most trouble- free on the market. To access the flywheel key- remove the nut in the center of the flywheel. You should see sevral threaded holes where you can attach a wheel puller. the key is right under the center of the flywheel. It stops the flywheel from turning independant of the crankshaft. Quick tip to determine spark or fuel problem; Take off the air cleaner, crank the engine over, give a quick shot of starting fluid, into the carb intake. If it fires, you r ignition is probably OK.

[Eugene]

Safety switches. Did you check all of the safety switches to see if one malfunctioned or is not in the "start engine" position or has been disconnected. Some lawn tractors have as many as 7 safety switches that have to be in the correct position before the engine's ignition will fire. 8 are listed below.

Try checking seat switch - someone has to be in the tractor seat.
Clutch out of gear.
PTO out of gear.
Tractor in neutral.
Brake locked.
Engine oil pressure sensor switch.
Carburetor inlet switch.
Mower deck.

On some engines - the engine will crank but the ignition is grounded unless the safety switches are in the correct position and functioning properly.

[John(videodoc)]

1. Readjusted the magnet next to flywheel to insure they were not touching, after i cleaned it up yesterday. stuck a thin piece of cardboard in between.

2. Sprayed with starting fluid, it started right up.
3. checked fuel line again, since i just replaced it, no fuel at carb. it was kinked under the main body assembly of the fuel tank, gravity flow. re-ran the line so it wouldn'g get a kink, fuel at the carb.
4. started right up.
5. Since the orginal problem was it died after 15 minutes or so of use, i am going to assume, that the pressure from the gravity fed fuel tank, was no longer strong enough to over come the kink in the bottom of the hose. Thus it was starved for fuel. Thus it wouldn't start
6. Thanks for you help.
7. I wonder how many times i will have to send this to get it to post. (I got problems with my home computers and ability to see and post on the board, usually takes an hour to do so, so i just avoid, unless i really need something, or want to post. Maybe when i get a new computer it will be different.)

John.

[junkman1946]

Sometimes they just have to "shake ,rattle, and roll" a while to stir things up and the problem dissappears. 15 min. run time, Check the needle valve for sticking. I too have problems posting with this site. I have Verizon FIOS. I also get"kicked off" a lot.