Interesting theory, and it could also apply to a poor/corroded connection as well that would simply heat and increase resistance until it was enough to stall the pump. Fuse would only blow if it was shorting to ground. Heat still means possible fire down the line.

...But, it would also be detectable when voltage is checked at/near the pump. Readings should be compared when there is no issue (cold start probably) and when the issue is exhibiting. A significant difference between the two would indicate electrical as the most likely culprit, assuming power is coming off the fuel pressure relay side properly. You just follow your wire, probing until you find your voltage drop.

If its not raining I may try the used pump, was told it was almost new, that came with the tank. I do not have to re install the tank to test it. Just dropped the tank and put some gas in a pail and put the sender/pump into the pail.

Wires were never messed with but rust deterioration could be possible. As I said it ran fine when parked a couple falls ago and last summer it did this right away when it was fired up. So That could be very possible that over the 6 months it rusted out even more and caused it.

I did let it run on a higher rev today to see if anything would happen. At the 18 min mark it started running poor and died. Would not start after that only fired and run for a sec or so. Volts were at 11.25 at the fuse before and after.

Now that you bring up corroded wires. I have a 98 lesabre that would do something somewhat similar. I would run fine and then just cut out. Not the more gradual way of this 1991 but instantly. And would not run for a hour so so depending on how cold it was outside. Turns out it was a bad ground inside the drivers door. Once that was fixed ran perfect every since. I do not know if this could be the same exact thing in the same exact place, but the drivers door is a mess.

Have you done these?

Those rumors seem to persist through the ages. Maybe it was done here or there, but I've personally only seen this on small engines like generators. Imagine if this were a thing on automobiles . . . every time that the PCM gets a false positive from an oil pressure sensor the car would quit . . . including power steering and the brake booster after more than a couple of brake applications. The first mass manufacturer to do this would learn a lesson really quickly.

Oil pressure, but yeah.

I agree as well, especially if the "new" pump came without a name. I often hear folks say things like "A fuel pump is a fuel pump. If it has a warranty then who cares." . . . until they have to (pay someone to) drop a tank again and again to replace it "for free" on warranty.

Yup . . .

Idling engine with vehicle stopped and in gear is the same regardless of direction selected. Accelerating from a stop is more difficult in reverse as reverse is geared taller than first.

I suggest getting a reputable manufacturer'* higher-end model.

I haven't seen the fuel pressure as "fine" yet.

I agree it would likely blow a fuse. Also the repeatable duration over many drive cycles would indicate something else to me. If it was a short and the fuse refused to blow for some reason, it would fairly quickly get worse and then change behavior.

Conversely, a bad fuel pump might change its geometry (Internally, like in the motor) as it warms up so maybe this is a factor. It could also be something related to cavitation if it has a bad impeller etc.

Is there a chance you checked fuel pressure right after it died before turning off the ignition?