TEA 20 Spontaneously Running Rough

Hi Everyone,

About a year ago my TEA-20 started spontaneously running rough. At that time I assumed it was temperature related since it was winter time (I live in Canada). When spring came around it seemed to run better. Later on I broke the timing chain and ended up having a professional partially rebuild the engine (machined head, new valve guides, new head gasket, new governor assembly, new camshaft sprocket, timing chain, timing cover). When I started it up it ran like a dream for about a week. Then it started sporadically running rough again... rougher than it was before. It almost seems like it's flooding itself. Gas flow seems to be constant out of the bowl. My mechanic mentioned some indications of arching on the points so I went ahead and changed out the points and condensor (gapped to 0.015") and installed a new coil. The wires on the distributor were changed out last year.

It's still running rough so I recorded it running https://drive.google.com/file/d/10D4GI668AYV5jiSSi9kZesVEPHxYVNjH/view?usp=sharing . I'm not sure where I should go from here. There is some slop in the distributor but I wasn't sure if this would cause my issue.

Any recommendations would be greatly appreaciated!

Thanks,
Julian

You say a constant flow of gas out of the bowl.

That is a sure sign of the carb flooding. Symptoms are black smoke, fouled plugs, gas in the oil, stinky exhaust, poor fuel economy.

Flooding can be caused by trash in the needle/seat, float out of adjustment, or sunk float.

One easy thing to do, turn the fuel valve off, start it up, see if the engine levels off as the fuel drops in the bowl. Go ahead and let it run until it quits, then turn the fuel back on, see if the flooding stops. Sometimes doing this will flush the trash out of the needle/seat.

If that doesn't work, take the carb off, take the cover off the bowl, take a look inside. The float should pass the "shake" test to check for fuel inside one of the pontoons. Pull the seat out, clean and inspect the seat surface and the needle. It can usually be reused. As for the float level, I don't have the spec, but good judgment will usually get it close enough. Look for a stain line where it has been floating for years. With the top inverted, that line should be parallel with the gasket surface.

After you put the carb back on, before connecting the fuel line, flush the line. Put the open line in a clean glass, open the fuel valve fully, see what you catch. If rust comes out, there is a problem in the tank, as in it's contaminated with rust, grit, whatever might be in there. It will need to be removed and cleaned out, or replaced if heavily rusted.

Be sure to check your oil for fuel contamination. The plugs may need to be cleaned if gas fouled. Also, has the mesh in the air cleaner been cleaned? Often overlooked, can be caked with dirt, also check for mouse nests, mud dobbers up stream.

And, play in the distributor is a problem. The points adjustment is critical, no way to properly keep them adjusted if the shaft bushing is worn. A rebuilt distributor, or point eliminator electronic conversion are the choices.

There is a hidden fuel filter inside the tank of a TEA20 tractor , made of bronze mesh , very fine and almost always corroded to the point of destruction .
This leaves a jagged outlet that will snag any fuel impurity , and lots of little bits of bronze mesh that find their way into anything .
The fix is easy , remove the fuel tap from the tank and discard any remaining part of the filter , flush the tank and blow out the tap with compressed air before replacing . While you are there look very carefully at the bronze mesh in the fuel bowl , this sometimes glazes over , it can look clean but could really be partiallysealed by transparent gum .

Thanks for your recommendations everyone!

I cleaned the carb but I'm having the same issues. this tractor has never run well so I ordered another carb to see if that will do the trick. In the meantime I will inspect the fuel and air.

I cleaned out the old oil in the oil bath but I did notice that there was some larger pieces of crud stuck in the mesh above the oil. Is there any way to remove the mesh and clean it?

If I installed a point eliminator electronic conversion kit, like the Ingitor sold on this site would this eliminate any electric issues, at least as far as the distributor is concerned? I was looking in to this and it seems it would make a difference.

Thanks again!

Julian

This shows the air filter top after the bowl has been removed . The mesh can be taken out once the spot welds of the retaining screen are drilled out . This is easier if the entire air cleaner is removed first . Carefully pull out the mesh and wash in Kerosene or petrol , no amount of washing with the mesh still in place will clean it as well .
Once clean , oil lightly and replace , the spot welds can be replaced with pop rivets or short self tappers.
Sometimes the mesh is very corroded , if it's too bad you can buy new replacements or use jumbo[u:cc1134785d] stainless steel [/u:cc1134785d]pot scourers , ones with no soap added , available from any supermarket .

Thanks Charles!

I pulled the oil bath off and cleaned it up and changed out the oil... I wasn't quite ready to go ahead and clean out the top of the filter. I took a step back and took another look at my electrical. I re-gapped my points just to make sure. Even though my spark plugs were about a year old they were fowled so I changed them out with new ones. One component that I overlooked was the rotor which was corroded. I cleaned it up and now it's back and running as smooth as it was running after the partial rebuild!

Thanks for the help!