Briggs Stratton 243431

I am not an expert on small engine repair so any hints would be appreciated.

The tractor has set in a shed uncranked for about 20 years. I cleaned it off, put some marvel mystery oil in the cylinder and hooked up a fresh battery. It has the combination starter/generator which seems to be working fine and the engine turns freely.

I have cleaned the exterior of the carb, removed and cleaned the mixture valve, and sprayed a couple of cans of starter fluid though it while trying to get it to start. It has never given any indication of life during all this.

Several times, I have dumped a small quantity of gas in through the sparkplug hole and then tried to start it. Two times, this has resulted in the engine starting and running for a few seconds. I cannot come up with an explanation as to why it started this way but did absolutely nothing while trying to start it with starter fluid.

There are a couple of mysteries that I would like to resolve. I have tried pouring gas down the air filter hole, the gas then runs out of carb through a hole under the choke. Is this hole supposed to be open? The second mystery is a wire dangling in the vicinity of the points mechanism. The wire is attached to another wire via a terminal attached to a piece of bakelite material. This appears to have broken off something but I cannot find where.

I am becomming obsessed with getting this thing running. The long story is that this is my father-in-law's. He is 80 and has not been able to use any of his power equipment for at least 15 years. My in-laws health has declined to the point where my wife is having to stay with them and I am staying there on weekends. I have made it a project to get all of the gasoline engines on the place back into running order. There is this tractor, a Massey Ferguson MF135, a Toro Wheelhorse mower, a Lowes mower, and a couple of extremely antique hit and miss engines. So far the Massey Ferguson and the Toro are running.

During my search on the web I have found a great site for parts. They have PDFs of the illustrated parts guides for many engines including this 243431. Here is the URL.

Link

I have been to the simple tractor site and found some useful information. I had not noticed that there was a members section. I'll go back and check it out. Thanks

Here is a link to the best online picture I have been able to find Link

In>Link this picture and on the actual unit, the carb bowl and the air intake pipe with air cleaner all appear to come off in one piece. I am concerned that if I take this apart, the gasket will disintergrate and I will be worse off. Also it doesn't seem to jive with the descriptions of how to take it apart.

When I have removed the plug between starting attempts, it has always been wet. Removing the plug wire and holding it close to a head bolt while attempting to start results in a weak looking yellow spark. I suspect that the condensor may be weak from setting all of those years but I have not yet located a source for a replacement. When attempting to start it while spraying starter fluid, it appears as if the starter fluid is being exhausted through the muffler.

It does not appear that there is anything left in the hole under the choke mechanism, should I plug it?

One the subject of the dangling wire. How does the ignition work on this thing? I am accustomed to working on old auto engines with points and on lawnmowers with magnetos but this engine appears to be somewhere in between. Does the dangling wire serve only to kill the system when the key is switched off or does it provide power to something when the key is switched on?

The terminal block with the two wires attached, is mounted to the upper screw holding the breaker-points cover. ...A wire from a key switch or grounding switch is connected to the terminal to shut the engine "off." .....The fiber insulating block prevents the ignition from grounding to the mounting screw.

Some other things to check:

1 - Verify that the choke is closing completely when the choke cable is pulled.

2 - Starting when primed, but stopping very quickly, is often an indication of clogged carb passages. ....You may have to disassemble and clean the carb.

3 - You did not mention if the ignition produces a strong spark from the spark plug wire. ....A good spark is blue in color, and should jump a 1/8" gap with no problem. ....A weak spark will appear yellow in color, and may be erratic.

Clean the breaker points with VERY FINE sandpaper, or a piece of paper. ....A slight bit of corrosion will affect the spark quality on these engines.

4 - With the air filter removed, cover the air intake with your hand, while cranking the engine. .....You should feel a strong suction on your hand during the intake stroke.

If there is no suction, or it is very weak, this usually indicates a valve that is sticking or not seating properly, a blown head gasket, or worn piston rings.

If you feel a strong suction against your hand, the engine should draw fuel from the carb, assuming the carb, fuel filter, or fuel line is not clogged. ....Crank the engine (with the spark plug installed) for 10-15 seconds. Remove the spark plug, and check for wetness. ....If the plug is dry, you are not drawing fuel in, so there is a clog in your fuel system. .....If the plug is wet, you need to check the ignition, and make sure you do not have water in the fuel system.

5 - If you can get the engine to run briefly after pouring gas in the spark plug hole, try to keep the engine running by spraying starting fluid into the air intake (choke OPEN). .....If you are VERY lucky, you may be able to get the engine to stay running on its own fuel supply. Sometimes, as fresh fuel is drawn in, the carb will clean itself.

6 - As a starting point, close the main (high-speed) carb adjustment (at the bottom of the carb) by screwing it all the way in BY HAND. Back it out 2-1/2 turns. .....Turn the idle mixture screw (the small horizontal screw) all the way in, and back it out 1 turn.

These settings will allow the engine to start if everythng is OK. ..When the engine is running, final adjustments can be made. .....The main adjustment will probably have to be turned in until the engine runs smoothly at higher speeds. If the engine hesitates when accelerated quickly, back the adjustment out slightly.

The idle mixture is adjusted after the main mixture is adjusted. ....With the engine idling, turn the idle mixture in slightly until a smooth idle is obtained.