Try the gasket under the carb first. Do you feel resistance when you pull the cord?

It seems like you covered your bases.

"and also there is occasional smoke that comes out from the crack where the top of the engine that the spark plug sits in and the bottom of the engine are bolted together so that gasket might be bad too. "

That's the head gasket which NEEDS to be sealed.

When you had the diaphragm off, you should have used the spray tube of your can of carb cleaner and blast through the 2 holes underneath it.
One goes to the pick up tube and the other to the venturi.
Carb cleaner should flow through both.

The engine will be 39 years old next Feb!

This post was edited by bill_kapaun on Thu, Nov 14, 13 at 22:03

I didn't have the carb cleaner when I replaced the diaphragm so I'll give that a shot when I get home tonight. Do I need to worry about the diaphragm being destroyed by the carb cleaner though if it gets on it?

What I'm wondering about is why the thing won't even start for a few seconds even with gas in the spark plug hole...it's definitely sparking!

The head gasket appears to be metal and in good shape, although I'll still replace it. I went to the hardware store last night to get a gasket set but they were out of the one that I needed, so I'll try elsewhere tonight.

Also, I do get good resistance and good compression when I pull the rope.

My suspicion is that the head gasket is not your primary problem. You indicate you have compression. The plug is new, but we don't know if you gas fouled it. It only take a little spray of fluid to make and engine kick. Since it's 40 years old, you have an adjustable main jet. That's where you need to check.

Mark it's current position by turning it in until it lightly seats and record the number of turns. Remove the jet. Spray carb cleaner into the jet hole. Put the main jet back in. Turn it back in until it lightly seats and back it out 1 1/2 turns and start there.

If it doesn't start, remove the carb and diaphragm and any other removable adjusting screw and spray carb cleaner into every orifice and blow with compressed air.

I did end up getting it working again last night after I replaced the head gasket actually and tilled a few rows of the garden but it's not entirely fixed yet. The fuel tank gasket is beyond shot, so when it runs it's leaking fuel out from between the carb and the tank (or at least I'm assuming the reason fuel is leaking is because half of that gasket is missing). I didn't replace it last night because it was getting dark and I didn't feel like screwing with the carb at that point so I'll do it today.

Second problem now is that it runs on pretty low power now, which I'm assuming is an issue with the carb jet being out of whack. I'll adjust it today and see if that makes a difference now that it's running.

Third, and this was totally unexpected, but I can live with it, is that it won't shut off now with the throttle lever! The wire is hanging out below the fuel tank, so I thought if I grounded it, it would shut off, but that didn't do anything, so I just disconnected the spark plug. Not 100% sure where that wire is supposed to go, but I'll figure it out...

Regardless, it's miles ahead of where I've been for a couple of weeks now because it actually runs!

There's a very good carb tutorial at the link-

According to the IPL, that engine had the metal tab that was "flipped" to ground out the spark plug.
Apparently, this has had the magnetron "upgrade"??
There's "probably" a tab on the coil that the wire attaches to.

Here is a link that might be useful: Carb

That's a great link there, thanks. For the time being, I hooked the wire around a spring on the throttle cable so that when I push it all the way to "stop" it grounds itself on a bolt.

I tilled my whole garden under this afternoon and I'm letting it run out of gas right now so I don't have to deal with this (hopefully) in the spring again.

The mission for this winter is to get the two nuts missing off of the governor control rod. Right now I have to open the choke manually which isn't a big deal, but it's just two small nuts that are missing. The diagrams I have say #5-44 thread but I got some of those the other day and they're way too big. I have a #3 that fits the diameter of the rod but the threads are off and I can't thread it on past a turn or two.

Thanks for the help!