I assume you are talking about the Suzuki 47P engine used on both Commercial Proline and Consumer Toro mowers from the early 1980's to about 2003. Great engine with few weaknesses but parts have always been expensive and are getting harder to source. Given your symptoms, I would follow the earlier advice, and also consider the coil and the crankshaft seals. Coil can be a weak area, and they are expensive. Earliest ones (to 1986) used breaker points and 81-1990 coil; later with electronic ignition used 81-2820 ($140.00 to $160.00 online). If crankshaft seals are leaking because of wear, this can cause hard starting and low power as crankcase pumping is affected. Parts are fairly cheap ($6.00 for 81-0720 Upper and $8.00 for 81-0740 Lower), but a major amount of labor to split the cases and replace the seals. When the mower dies and won't start, try burping it with some ether starting fluid. If it lights up and then dies again, you have a fuel related problem. If it won't run even on starting fluid, probably not carburetor or fuel supply, but ignition, compression, or elsewhere. Before you get too deep, is this a Commercial mower, or is it a Consumer? Also look at overall condition. A lot of Commercial Prolines were rode hard and put away wet. Although the owner and crew boss were usually pretty careful, the laborers just ran them until they quit. By now, even the latest Prolines are near 10 years old and have had a lot of hard use. Consumer mowers had fewer hours, but were often neglected. You said yours is 25 years old!!! A Commercial in very good condition is worth $500 or more. At the same time a Consumer machine might only be worth $200 or so. You need to make a hard eyed judgement whether restoring the machine makes economic and operational sense. Call me silly, but I can't see sinking $200 in parts, plus several hours professional labor in a machine that is only worth $200 or $225 at the end of the day.

I posted this in another thread, but it applies here too since the coils on the Suzuki 47P are in discussion; http://gardentractorpullingtips.com/images/novainst.gif ..."The big problem with many of todays small engine coils is they have their electronic spark triggering diodes (vs. yesteryear's spark triggering mechanical points) epoxied directly into the surface of the coils themselves. This is that little 1 inch square "bump" visible on the outside of the otherwise cylindrically shaped coil consisting of copper windings. This little "integrated" diode takes a lot of abuse by constant engine heat and vibration and eventually gives out ..at which time the owner finds out he must replace the entire coil assembly (even though technically the coil itself is just fine), to the tune of $200+ in some cases. The coil on the famously popular Suzuki 2 stroke 47P engine on the older Toro commercials is notorious for crapping out like this and folks get a few more miles out of those coils by cooking them in their kitchen oven for 20 minutes at 220*f. Its not exactly clear how this works to temporarily "fix" the coil internals, but its often successful. If someone were to open up the epoxy & paper covering from one of these coils and replace just the bad OEM diode by wiring in one of these aftermarket diodes, there would be many grateful Suzuki 47P owners. Alternatively, bypassing the diode and going back to mechanical points trigger (such as found only in the 47P's first year of production 1983) would also be a solution."..

I decided that since I removed this coil from the engine I put on the reconstructed 10525, that I would put it right back on that machine, since it has been my primary mowing machine this year. Its been a great mower and I know what to expect from it. So I installed it, removing the new coil I put on previously and adjusted the gap. Put it all together and she fired off on the first pull. :) Now I mowed the front and both side yards this evening, about an hours worth. I saved the back yard for tommorrow evening when I get home. It will be in the garage all day and out of the sunshine. So that will be a good test for a cold start. Ill let you know what happens and Ill keep you updated on how long it lasts. If she holds up that will be a nice plus and I can put the newer coil up for spare. These are 99-2911 coils from what I can tell or 2916. They both look exactly alike and work in all Duraforce engines.

Just to update this thread with a little info useful to some Lawn Boy users in this depressed economy. The older F engine coil module 683215 /683080 can be used to replace the Duraforce engine 684048, 684049, 92-1152, 99-2911, 99-2916 coil. It takes just a few minutes of grinding and filing modifications to the coil legs and one of the mounting bosses on the block. The engine starts and runs perfect with them so the timing must be very close to the same if not dead on. I have never compared the 2 with marks and a timing light but suspect there is no difference. I have recycled numerous modules from old dead F troop soldiers to newer Duraforce units. They are open to run modules as well so there are no wiring issues to work around.