4 HP Tecumseh H40 Won't Start, No obvious Spark

[RoyzMG]

I've been trying to start an older H40, but there is no spark. I replaced the spark plug and the solid state ignition but still no luck. Triple checked the magnet to coil gap at about 0.012". I've removed the engine kill lead from the coil and still no spark. It appears to be a very simple ignition system with the solid state coil. What am I missing?

Thanks in advance,
Roy

 

[BlazNT]

To start it should be .010. Try that and let us know what happens.

 

[Rivets]

If changing the air gap doesn't work, please post the Spec number.

 

[RoyzMG]

I changed the coil-to-magnet gap to 0.010" and still no spark. The Tecumseh Tech Manual specifies a gag of 0.0125" (0.317 mm) and says I should use a special tool #670297 to set the gap. I've been using a feeler gage since I don't have this tool. I've seen some posts on this forum that say to use a business card to set the gap but the Tecumseh manual says don't use a business card. It is a bit difficult to use a feeler gage.

The solid state coil is new and the spark plug is new. What other problem could there be?

Also the spec for the engine is H40 55805A (A) if that is what you were asking for.

 

[RoyzMG]

I also performed the "rough" magnet test recommended in the shop manual of using the screw driver to test the strength of the permanent magnets and they have plenty of strength.

 

[Rivets]

I'm assuming the coil you installed is part number 34443D. .010" is the gap I use on all Tecumseh engines, and I set them with a long (8") steel feeler gage. Many on this site use a business card, which I have used away from my tool box. Have you checked that the coil is installed properly. The ground wire tab should be up, away from the block, not down. Many have done this which will result in a NO SPARK condition.

 

[RoyzMG]

Thanks for the comments. The coil is mounted correctly. I pulled a compression check on the engine. With the throttle wide open and the cylinder dry I got a 50 psi reading after several pulls of the rope. Squirting some oil into the cylinder, the pressure came up to about 60 psi. I believe the normal reading should be around 80 psi. Sounds like maybe the rings are worn.

Any comments?
Roy

 

[Rivets]

At this time I wouldn't be concerned about those readings, they don't contribute to no spark. Remove the kill wire from the coil and check for spark. No spark means bad coil, spark means kill wire shorted to ground.