Hi guys ill see if you can help me out here, 1991 f250 300 six the fumes are so bad in the truck i can drive it, do these trucks have oxygen sensors? any idea on how to check the codes, any ideas good bad or even ugly are welcome

 

Yes the 91 has an O2 sesnsor. Check your AIR system check valves, EGR tube, and the exhaust pipes as they pass under the cab. The cab floor has several cutouts that are sealed with rubber plugs, make sure they are still there. You might have rust issues on the cab floor too.
regards
rikard

 

Stuff the tailpipe with rags & listen for hissing & huffing forward of the muffler while the engine idles.

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