I have a 1986 Gran Fury with 5.2L/2BBL and "Lean Burn" feedback carb. Occasionally, when cruising at higher speed, (typically around 75 MPH, but can happen as low as 45) when throttle goes from just above idle to a little farther open, does several seconds of severe "bucking" or surging. Troubleshooting has been: replacing carb with non-feedback type didn't help. Blocking off EGA vacuum didn't help. Swapping out computer unit reduced frequency of occurrence, but didn't stop problem entirely. Disconnecting and plugging vacuum to computer stops problem, but causes loss of power and open-loop, gas wasting carburetor operation. Vehicle needs to keep lean-burn stuff on to pass MD emission inspection. Engine otherwise runs well, passes inspection with 1/10 allowable emissions. Alldata doesn't show any TBs for this. Has anyone else seen this sort of problem, or have any suggestion?
"Bucking" with '86 318 lean-burn
Jun 07, 2005
2 Replies
Wow. No one else runs lean burn anymore! Secretly plugging the vacuum line and reworking the carb to run conventionally might fix problem. Or perhaps you could fit EFI and a catalyst in your state, since there is no more leaded gas anyway. Finally, you could convert to LPG...
And leaded gas has exactly what to do with an '86 *anything*, pray tell?
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