'61 stumbling/stalling after acceleration

[James Landi]

"Almost textbook for a fuel filter.  When you stop for a little while the crud restricting the filter migrates away from it, but then comes back soon when the engine is restarted.  Could be the electric pump has enough extra "push" to get sufficient gas through the restricted filter and make the engine run normally.  An idling engine requires little fuel."  Geoff


David,

If your car has the original fuel tank, there's likely all kinds of crud that your fuel supply pipe and filter are attempting to vacuum clean one tablespoon at a time. Once your Cadillac is on the road, normal driving agitates the gasoline and crud, partially blocks the filter and your engine stumbles under load  I've experienced fouled fuel tanks on several occasions and the problem is NOT easy to fix.   For diagnosis purposes, a fuel vacuum gauge would be helpful as it would eliminate whether the issue is crud fouling the filter or a bad fitting or pin hole leak in the fuel line or a weak fuel pump.  Geoff is absolutely on target that when the engine is under load, any lack of fuel pressure (i.e. fuel volume) will cause the engine to stumble.   Replacing an ancient fuel tank, all of the fuel hoses and filters is expensive; however, this may be the only way to make your car reliable. 

[David Greenburg]

I doubt it's a filter problem, as I replaced the filters back when I was wrestling with this issue in the Fall. And the tank was replaced under prior ownership when the car was recommissioned about 15 years ago, after its 30+ year nap.

I am on some temporary physical restrictions following eye surgery, so I can't go underneath to poke around, and getting a rebuild is going to be cheaper than paying a pro to poke around. I do have a couple of used Airtex pumps that have been sitting in my "parts department" that I could
try as a test. No sure if they're still any good, but with the electric available as a backup I could do a road test without getting stranded.