Saturday, November 20, 2010

Craftsman riding lawn mower ignition coil/timing problem?

I have a 2005 craftsman 18 hp riding mower with a briggs and stratton motor (model 31H777). The mower would start and run great for 20 minutes then start sputtering like it was out of gas but never turn off. I was told the ignition coil was going bad so I changed it and gapped it correctly to manufactures specs. Now it will not even crank. Did I mess up the timing when I turned the flywheel 3 or 4 times when I was trying to set the ignition coil gap? If so, how can this be fixed? Thank youCraftsman riding lawn mower ignition coil/timing problem?
I doubt that the timing is off. Check to see that it is firing with the new coil. Its possible you missed something. These engines are switched off by grounding the coil, check that the small wire coming from the coil is not pinched between anything. It could be a problem with a safety switch. If it is firing make sure it is getting fuel, try putting a few drops of gas in the carb or use a starting fluid. If it tries to start then the problem is in the fuel system. Carb could be clogged or if it is a twin cylinder it could be a bad fuel pump.

There is no adjustment for timing on lawnmower engines. It is possible the gap is too large or the flywheel could have sheared a key which is rare on a riding mower.

Even if the timing is off (sheared key) you should still have a spark. If you have a spark and it will not try to start and run when you put a few drops of gas in the carb or use starting fluid then you need to pull the flywheel and check key.Craftsman riding lawn mower ignition coil/timing problem?
Thanks to all. Problem was not anything to do with coil. ( I have 2 coils now) Fuel solenoid attached to bottom of carburator bowl going bad. Changed air filter also, something I should have done first. Runs much smoother. I could bypass solenoid but think I should buy new one.

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Craftsman riding lawn mower ignition coil/timing problem?
the flywheel should have a key way on the shaft, so you can,t get it out of time, what gap did you set it at ? try 10 - 12 thousands

points at 15 thousands

you say it wont crank, is that turning over ? or not starting ?

set the plug at 35 T use a hot plug , like a B-17 are you getting spark?Craftsman riding lawn mower ignition coil/timing problem?
Not even crank? or not even fire. Timing really shouldn't be an issue. Unless you removed the flywheel, you shouldn't have done anything to compromise the timing. More than likely the air gap is wrong. The way we did it in the field was to tear open the box that the module came in and use that to gap the module. It never failed. Metal feeler gages and magnets don't seem to work well together. Did you gap it on the magnets or off, you need to gap it on the magnets. If you can't get it to run with the new one, put the old one back on and see if it runs again. Then post an update. I check back once a day at least until resolution.Craftsman riding lawn mower ignition coil/timing problem?
The air gap is not a critical measurement so long as there is a gap. With the magnets adjacent to the coil the gap should be set. I don't think that you can install the coil upside down or at least you can't on my Kohler engine. You did not mess up the timing. You would have to remove the flywheel to effect the timing. I would check the spark with the new coil. If you are not getting spark, disconnect the ground wire from the coil and try it again. Most often when a coil is bad they quit completly when they get hot not just make the engine run bad. You could be working on the wrong problem. The first thing to do is determine if you have spark with the new coil.Craftsman riding lawn mower ignition coil/timing problem?
Well for the original problem, I just went through the same thing. It turned out to be a dirty fuel filter and my fuel cap was clogged and not venting the tank. That combination would let my mower run about 30 minutes and then start sputtering and coughing.If I loosened the fuel cap it would run another 30 minutes. If the engine will not even crank , that has nothing to do with the timing. I would start by putting the old coil back on and gaping it with card board and thoroughly check for loose wires especially around the starter solenoid and the starter.

Make sure the battery is fully charged. Unless you put the new coil on wrong somehow, it will have nothing to do with keeping the engine from at least cranking.Craftsman riding lawn mower ignition coil/timing problem?
william is on the right track,, there probably wasn't anything wrong with the coil!! the key was probab;y sheared but just holding on then it fell apart when you worked on the coil,,, hitting something hard can cause the key to shear,,!! and if you pulled the flywheel when you worked on it the pin may have fallen out and you didn't notice!! so it is way out of time now,,Craftsman riding lawn mower ignition coil/timing problem?
the term cranking is just the mechanical process of connecting the battery to the starter motor and the starter motor engaging the flywheel and spining the cam, thus causing the engine to turn and allowing all components to move in the manner expected at start up.

To fire means for a charge to reach the spark plug and for it to ignite the compressed air/fuel mixture at the proper time that allows for it to explode and drive the piston down in the cylinder. If everything is set correctly, this will continue after you release the key. It sounds like in your case, the engine used to do this, but now no longer even fires.

i agree that one possible cause is changing the timing. If you can find the shop manual for your engine or one very similar to it, you can probably get the sequence for adjusting timing. In the old days you needed a timing light for that, but maybe its no longer necessary on a modern B%26amp;S.

Sorry I can't be more helpful.Craftsman riding lawn mower ignition coil/timing problem?
first replace the sheer pin that aligns the flywheel and to space the coil I always just placed a business card between the coil and the steel part of the flywheel with the screws loose. when the magnet sucks it up tight then tighten the screws and pull out the card. make sure the wire isn't,t grounding out or broken.Craftsman riding lawn mower ignition coil/timing problem?
Your original problem was fuel related me thinks, probably fuel cap or filter as the other chap mentioned. If the motor spins over and gives you a spark and your plug comes out wet then you have either dislodged the key in the keyway on the flywheel or you have sheared it off somehow, these are very soft and I once had one shear through a backfire.