Late '80's vintage 18HP, 44" rider. Been running like a champ until recently. Started running very rough a couple of weeks ago. Had to choke all the way to keep in running. Decided to start with new spark plugs to rectify. Now I don't get any spark. Turns over just fine. Amp meter on dash reads 0 however when ignition engaged (seems like it used to read higher?? ). Reads minus when turning over. Checked fuse, OK. Ran test on Diode assy. w/my multi meter (a little out of my element here). Got a reading with probe in either end. Not sure if that is okay or not.

Thoughts?

The amp meter should go down when it has a drain on it, like when starting... be above the middle mark when charging. (diode keeps things from frying)

80's? What's the exact year on the engine... could have points.

The actual purchase date from the receipt I have is August 1989. The model number on the B&S engine is 422437, Type number 1256-01. Model number on the tractor is 917.255919.
Does that help?
Thanks, Rick

Can't tell the year of the engine without the code.

Where on the engine would I find it?

It should say model, type, and code... all three sets of numbers in the same location.

Any ideas on where I can find the code number? Is it usually stamped on the case or a label? I've got the front hood off and I've removed some of the sheet metal around the cyclinders but I can't find the code at this point.
Thanks,
Rick

Kind of weird not to find it right in-line, side by side with the model (then the numbers under it) type (then the numbers under it) and code (with the numbers under it).
Either stamped right into the shroud or a aluminum tab riveted on with them.

'94 chevy silerado