Engine Performance problem
1987 Mazda b2200 4 cyl Two Wheel Drive Automatic 142000 miles
Hi, My truck runs great generally, but the mpg has dropped to about 18. As well, it won't pass the emissions test because the fuel mix is too rich and is generating too high levels of the bad gases. I have not rebuilt the carburetor, but I have had several things adjusted and looked at on it. Everything appears to be in order. Another clue is that when the fuel filter becomes dirty and needs to be replaced (which happens about every 3000 miles), I start getting better mileage as the truck stops getting enough fuel to run (when the filter gets dirty, the truck will lose power, want to die. Let it sit for a few minutes and then it'll start again and go for another 10 minutes or so before dying again). Replace the fuel filter and the truck runs great again, but mpg goes back down. I've been told that there is a sensor or something in the carburetor that controls the fuel richness, and I need to replace that. However, I don't know what it is called, or if it is included in a rebuild kit or sold separately. Any help?