funky running when on reserve

[Triumpy boy]

Ive been lurking on this site for years however Im baffled by a fuel delivery issue. My 82 hearitage runs just fine until the fuel level gets very low then the left cylinder cuts in and out. Opening the throttle will improve this situation but only until let off. If I stop and fill up things are grand again.

 

[arcticXS]

Partially blocked strainer (mesh filter) on the reserve bore of the petcock (s)?

 

[grizld1]

Common problem, crud settles to the bottom of the tank and blocks fuel feed when you switch to reserve. Remove the petcocks and flush the tank with water at the car wash or with a pressure washer, then rinse with a bit of alcohol to pick up any remaining moisture, or blow dry with the outlet of a shop vac, or borrow the wife's hair drier.