Hi, I inherited an '89' Toyota base 4-spd manual, carbureted, California emissions, pickup. (It does have factory air but otherwise only has the standard features, doesn't even have pwr steering.) The MIL light came on a couple of days ago and flashes the ODB1 code, 26.
This truck has 203000 miles and was maintained through the "if it isn't broke" philosophy of auto care. It wasn't running when I got it but after I rebuilt the carb it passed smog and ran great. The past several weeks it has been acting strange meaning it runs good one time and then, on the next start, barely idles, backfires when coasting, and diesels when I shut it off. I figured the carb is worn out (it was really dirty when I rebuilt it) so I ordered a rebuilt carb which hasn't arrived yet. (This all took place before the check engine light came on.)
Everything I've found on line in terms of diagnoses and repair pertains pickups equipped with EFI systems, i.e. cold start injector, etc. Anyone know how to diagnose a carbureted version?

 

Don't buy this, see if the local library can get this

Lots of easy step by step diagnosis
Has stuff about the carb and rebuild and adjust