After years of on and off symptoms of an empty fuel bowl under load, I’ve finally found the source.
I’ve struggled with limited range and what I thought was boiling of modern fuel or vapor lock issues.
I finally dove head first into this and changed everything. Pump, lines, return to OEM rigid lines, etc etc. Same problem but worse. Bucking, sputtering, and inability to climb/drive reliably.
I broke down my pride and took it to a mechanic. Through isolation techniques with electric fuel pumps, pressure gauges and fuel cans, the problem isolated to the carb.
We were getting fuel pressure to the carb with pressure but an empty bowl under load. Inspection of the carb diagram let to the AAAH HA moment
The banjo bolt fuel restrictor was the key.
The center console was removed and pinching the fuel return line solved every fuel starvation/delivery symptom. Immediately. Until the return line was uncrimped and all the problems immediately returned.
Turns out I happen to have a “spare parts” carb that was the actual original to the truck. The prior owner put a later year carb on the rig due to a vac leak at the butterfly shaft bushings. That carb worked (sort of) but had a banjo bolt with no restriction. 100% of fuel was flowing to the tank via the return with no restrictor. The path of least resistance was to the return of the tank and there was not enough resistance to force fuel through the needle valve under load.
Later banjo bolt
correct banjo bolt with bushing and restrictor.
Immediately we had correction of the symptoms and the mustard is flying.
Downhill with the wind of course.
It’s been a frustrating road but I think I can leave town now without fear and worry of bucking and sputtering
hOOter
