Engine Loses Power on Hills - UPDATE in this Post

[Pilotdave]

I'm working with a Model A friend whose engine is losing power when the car is climbing hills. Runs well on level roads.

I haven't yet touched the car, but I'm trying to think of possible causes. Here are three that perhaps could make the list:

1. Something floating in the gas tank that obstructs fuel flow on uphills.
2. Partial gas line obstruction that restricts fuel flow enough so that the engine can't get enough gas in high demand situations.
3. Float level issue.

Do any of these make sense? Are there other possibles that I should put on the list?

Here's the update:

The car is a '29 Tudor converted to a 12v system; engine rebuilt several years ago. Here's what we found and did:

1. Worn/misaligned points; replaced and set gap.
2. Yellow spark; replaced condenser.
3. Spark plug gaps and condition fine.
4. Timed engine.
5. Weak fuel flow; car has an ancient shutoff valve and no pencil filter - deferred replacement as parts were not on hand.
6. Discovered advance/retard arm not able to fully retard; it was half-way between full retard and advance with the driver lever fully up. Straightening linkage rod helped but didn't fully cure this issue as the arm doesn't quite reach fully retarded position.
7. Re-timed engine with advance/retard linkage disconnected and arm in fully retarded position.

We test drove the car after steps 2, 4 and 7 and noted improvement after 2 and 4. But the car still performed poorly in our view. It wasn't until we realized that there was an issue with the advance/retard arm, addressed most of that, and re-timed the engine that the car came back to life. It now gets up hills in 3rd gear that it had trouble negotiating in 2nd at the start of the process.

Here's our theory/guess about this car: With restricted fuel flow and timing effectively retarded, the engine was working from a real deficit. This is the only A that the owner has driven, so the report that it was "running okay" likely wouldn't have felt okay to a more experienced driver. So what happened on the way home from the tour when the car suddenly started having trouble climbing hills? Something pushed that poor engine over the edge - we're guessing that it was the points, perhaps in combination with the condenser, that did the job on an under-fed, poorly timed engine.

The fuel flow issue still needs to be addressed; doing so should further improve things.

Thanks to all of you who offered suggestions - much appreciated.
Dave