I've seen guys on more advance diagnostics YT videos hook up a scope to the fuel pump and look at the electrical waveform. You can look at the condition of the motor brushes or commutator(?).
A basic scope is on my things to buy sometime. They are pretty expensive even for the a basic model.
ABSOLUTELY.
You'll need a digital 'scope that can "freeze" the image, and a low-current (amperage) probe.
Set up the 'scope so that it's reading the signal from the low-amps probe, with the probe connected to the power-supply wire of the fuel pump. Adjust the settings as needed to get a clear view.
You'll get a series of pulses on the 'scope screen that relate to the amperage draw of each individual fuel pump motor armature bar. Each one is like a fingerprint--they look exactly alike until you look close enough, and then each one is distinguishable from the others. Freeze the image, pick one of the pulses to study, then count the number of pulses until the pattern repeats. That gives you the number of armature bars in the fuel pump electric motor (usually 8, sometimes 12, but any number is possible depending on the design of the motor.)
Once you see the pattern repeat, you can use the cursor functions of the 'scope to determine the milliseconds between repeating patterns. And then mathematics can reduce that to the RPM of the electric motor. If there are gross differences in the amount of current pulled by one or more bars, the pump motor is probably junk. If the whole motor draws excess current, the motor is probably junk (or the fuel filter is plugged.) If the motor doesn't draw enough current, there may be an internal leak, or low fuel pressure due to a failed pressure regulator.
The secret to all this is to test multiple GOOD pumps, so when you suspect a bad one, you'll recognize something out-of-the-ordinary. The same principles apply when testing HVAC blower motors, power antenna motors, power seat motors...
Not a video, but I posted a batch of photos of all this on another site.
(Ad blockers will disable the photos. Once I switched-off my ad blockers, the photos reappeared.)
TBI - TBI--Fuel Pump Upgrade w/Photos - This seems to be the finest web site in existence for TBI information. While I recognize that this is primarily a Camaro/Firebird site, much of the information applies to GM TBI vehicles in general. In my case, I have an '88 Chevy K1500 work truck with the...
www.thirdgen.org