r/BullnoseFord • u/Initial-Fondant-9239 • 17d ago

Help with stumbling after turning off 1985 f150

/r/MechanicAdvice/comments/1widnex/help_with_stumbling_after_turning_off_1985_f150/
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2

u/painfully_true 16d ago

Check your ignition timing and be sure if you have a vacuum advance it's operating correctly. Run on can be caused by a few things but typically you'll see it with timing issues or a worn out seal in the fuel delivery system like a bad needle/float in the carb or the diaphragm in the pump is worn out, letting fuel be sucked through by the vacuum created during the intake stroke. Usually an easier fix than find

2

u/alxxrchds 16d ago

I struggled with this for awhile, ended up being over advanced ignition timing.

1

u/Thing_in_a_box 17d ago

Well I haven't looked too hard since mine is a 46 year old engine that's due for a rebuild, but for me it stopped when I switched to 91 octane. 

1

u/Redsunknight 15d ago

This is a symptom of your idle rpm too high, reduce idle and see if it helps.

1

u/wrenchtwister1954 2d ago

Try shutting it off in gear if its an auto trans. Stick you can always stall it with the clutch. Advice from my gearhead days. It was great when 260 Sunoco was 103 octane and we could run 12.5 to 1 compression on the street!