Hi All,

During the past few days, my 87 Westy has developed an over-rich problem. It runs fine for the first 20 minutes of driving after a cold start (like over night, or sitting for 3 or 4 hours). Then, especially at low rpms (<2500 rpm) it starts misfiring and running so rich I can smell the exhaust up front in the cab. At what should be idle, the engine dies. It starts right up, but I have to keep the revs up to 2000 so it will "idle". 

Even at 2000 rpm, it misfires. I rev it up to 3500 or so, and the richness problem seems to clear up. But, after a few minutes, it starts ru8nning rough again below 2500 rpm. Eventually, it clears up somewhat, and idles between 400 to 800 rpm.

Any ideas? Next week (after I return from a conference) I will be replacing the engine (Boston Bob unit) and transaxle (AA Transaxle rebuilt), so it would be good to know if I need to replace any sensors (will be replacing O2 sensor w/engine).

Thanks in advance.

Ric

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