Running with the choke out

Since the carb body is cast and the butterfly shaft is usually brass, the shaft will usually wear instead of the carb body.

Wouldn't hurt to doa visual and a wiggle first, to make sure the manifold is snugged up tight and hasn't developed a crack, and that the carb is snug up against the manifold.

For me, though, it"s all about TIME. I want to fix things as quickly as possible.

In order to do this, it is necessary to ISOLATE the source of the problem BEFORE adjusting, replacing, etc., etc., otherwise one is dependent on luck.

I also like to do the quickest checks first. Here, I think the fastest one is going to be squirting something suitable around and look for air leaks as described above.

After that, I would do a fuel flow check, especially if this tractor is kept outdoors when not in use. Pull the plug and look for a STEADY stream about the diameter of the plug. Let it flow for several minutes.

If the fuel flow checks out ok, I would run a spark test before going on.

(Yes, I KNOW it is counterintuitive. But weak spark CAN cause an engine to run much better with the choke applied.)

Make one of Dell"s calibrated spark testers. Get a good plug and bend the electrode out to 3/16"". Clamp it to ground. Remove ONE spark wire at a time and connect it to the test plug.

You want to see a nice, wide, bright blue spark. Weak or discolored spark is suspect.

Because rebuilding the carb is such a time consuming method FOR DIAGNOSES PURPOSES, it is last on my list. First I try to demonstrate to myself that the carb IS the problem.

The best way to isolate the problem to the carb is to substitute the one you have with a known good one. Not always practical, but I always like to mention it in case you are lucky enough (as an I) and there are still several Cs in use in your neighborhood.

Barring that, I have had good luck over the years on a wide variety of vehicles with the following approach, which will isolate a bad carb almost every time:

I try to tune the carb in accordance with the instructions in the shop manual. If the carb fails to respond to any of the adjustments, be suspicious of it. I"m not saying all the adjustments need to be able to make the tractor run perfectly; remember, we are still diagnosing at this point and the carb MAY NOT be the problem!

But you should generally see SOME KIND of response to each adjustment when performing the carb adjustment procedure in the shop manual.

Good luck. It will be greatly appreciated if you keep us posted so that we may learn from your experiences.