I am working on an old Tecumseh AH 817 MB engine. When I talked to the guy who owned it before me, he said it had no spark. He said he had tried putting in a different condenser but still had the same problem. I noticed when I took it apart that he had pinched the wire and I thought that may be the problem. So I purchased a new set of points and condenser, I used the numbers from his condenser to order mine, what I didnt know (he told me later) was that he used a different condenser than the original. I have a very weak spark, the only way I could tell was to hold on to the plug wire and turn it over by hand. (Now dont tell me nobody else has done that) I do feel a spark, however not enough to show when you put a spark plug in. So..... after that long explanation my question is... is there a difference between 2 cycle condensers and 4 cycle condensers, or does my problem lie in the coil? I know that this vintage engine is hard to find parts for, but if anyone has any or could cross reference what will work I would love to hear from you. Thanks
Tecumseh AH 817 MB spark problem
I like the old Tecumseh 2 strokes. (Edited: reading old posts I see several mentions of the AH 817 MB... always learning something new, never have seen one). Previously I thought there was only the AH 81...
One thing to check is the strength of the flywheel magnets. If a flywheel has been hammered, struck, dropped or heated it can lose magnetism. This could easily happen if the flywheel was stuck on the crankshaft. The later Tecumseh manual illustrates holding a large flat head screwdriver tip within 3/4" of the magnets... and if the strength is good it will pull the screwdriver tip onto the magnet. Weak magnets will not fire a spark plug.
The AH81 has a "3 pole" magneto ignition coil. The pole I am referring to is the machined edge of the metal laminations that mates to the flywheel magnets. The ignition coil has a pole in its center, with an exposed pole on either side of it. There is a small, adjustable gap between the flywheel magnets and the ignition coil's metal poles.
Tecumseh's small engines with magneto ignition, both 2 and 4 stroke varieties, fire the spark plug on every stroke. This is important for condenser acquisition, because the electrical value of the condenser for Tecumseh engines is the same (Edited: for the 3 pole magneto coil). As long as you ground the condenser case and wire it to the ignition coil primary (the small wire) and the points, you are free to use a Tecumseh magneto ignition condenser from another engine size or type.
This one would be great if you can fit it on there and wire it in.
If the points are grounded, or if that small coil wire is grounded, you get no spark. The kill switch circuit grounds that small wire to kill spark.
The coil might be burned out, though fairly rare it can happen. Get the correct condenser first. An AC magneto condenser is just not the same as any old condenser, even though it looks similar.
Good luck with it!
Jon
One thing to check is the strength of the flywheel magnets. If a flywheel has been hammered, struck, dropped or heated it can lose magnetism. This could easily happen if the flywheel was stuck on the crankshaft. The later Tecumseh manual illustrates holding a large flat head screwdriver tip within 3/4" of the magnets... and if the strength is good it will pull the screwdriver tip onto the magnet. Weak magnets will not fire a spark plug.
The AH81 has a "3 pole" magneto ignition coil. The pole I am referring to is the machined edge of the metal laminations that mates to the flywheel magnets. The ignition coil has a pole in its center, with an exposed pole on either side of it. There is a small, adjustable gap between the flywheel magnets and the ignition coil's metal poles.
Tecumseh's small engines with magneto ignition, both 2 and 4 stroke varieties, fire the spark plug on every stroke. This is important for condenser acquisition, because the electrical value of the condenser for Tecumseh engines is the same (Edited: for the 3 pole magneto coil). As long as you ground the condenser case and wire it to the ignition coil primary (the small wire) and the points, you are free to use a Tecumseh magneto ignition condenser from another engine size or type.
This one would be great if you can fit it on there and wire it in.
If the points are grounded, or if that small coil wire is grounded, you get no spark. The kill switch circuit grounds that small wire to kill spark.
The coil might be burned out, though fairly rare it can happen. Get the correct condenser first. An AC magneto condenser is just not the same as any old condenser, even though it looks similar.
Good luck with it!
Jon
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Thanks Jon,
Heres what I know so far. The magnets are strong, the gap between the coil and flywheel look good, the condenser that I put in is the exact same one that you recommended. I have added a few photos to see if anything jumps out that I am overlooking. I do not know why there is a terminal connector mounted with the other wires on the point block. I removed it and it is shown in my hand. Does a wire go there? Also as I stated earlier, I do feel a weak spark when I spin it by hand, also I hooked up a tester to both wires exiting the block and they do give me a weak light. I am open for any and all suggestions. Thank you
Heres what I know so far. The magnets are strong, the gap between the coil and flywheel look good, the condenser that I put in is the exact same one that you recommended. I have added a few photos to see if anything jumps out that I am overlooking. I do not know why there is a terminal connector mounted with the other wires on the point block. I removed it and it is shown in my hand. Does a wire go there? Also as I stated earlier, I do feel a weak spark when I spin it by hand, also I hooked up a tester to both wires exiting the block and they do give me a weak light. I am open for any and all suggestions. Thank you
Guys, I think you can still order some parts for this motor.
It is the same as sears 5.5hp outboard motor, Ted Williams / ESKA sold in the early 70s.
Tech made the power head for the outboard sold under sears/Eska/Ted Williams.
I think this condenser should work.
go to searspartsdirect:
Condenser
PART NUMBER: 30548A
Substitution: 33-008
This is a manufacturer substitution. Part may differ in appearance but is a functional equivalent to prior parts including 30548A.
Craftsman Sears Ted Williams 5.5 Hp Outboard Motor model #21759432
It is the same as sears 5.5hp outboard motor, Ted Williams / ESKA sold in the early 70s.
Tech made the power head for the outboard sold under sears/Eska/Ted Williams.
I think this condenser should work.
go to searspartsdirect:
Condenser
PART NUMBER: 30548A
Substitution: 33-008
This is a manufacturer substitution. Part may differ in appearance but is a functional equivalent to prior parts including 30548A.
Craftsman Sears Ted Williams 5.5 Hp Outboard Motor model #21759432
Glad to try and help.
Two connections to the points make sparks, and both are under the flywheel:
One wire is low Voltage AC power from the coils, generated by the rotating flywheel magnets.
The second wire is the condenser.
Any other wire connected to the points is a kill switch wire.
Grounding such a wire shorts the low Voltage AC power to ground, killing the spark.
Test for spark without any outside wire connected.
Safety note: if the engine is fueled and could possibly run during this test, be able to stop it using the carburetor, or pulling the spark plug wire.
If you have a multimeter that measures resistance, you can further test the points, wiring, and ignition coils to help locate the problem.
Jon
Two connections to the points make sparks, and both are under the flywheel:
One wire is low Voltage AC power from the coils, generated by the rotating flywheel magnets.
The second wire is the condenser.
Any other wire connected to the points is a kill switch wire.
Grounding such a wire shorts the low Voltage AC power to ground, killing the spark.
Test for spark without any outside wire connected.
Safety note: if the engine is fueled and could possibly run during this test, be able to stop it using the carburetor, or pulling the spark plug wire.
If you have a multimeter that measures resistance, you can further test the points, wiring, and ignition coils to help locate the problem.
Jon