Mechanical fuel pump failure

Have a 200 inline in the 63 E100 truck. Just had the third mechanical pump failure.

First was the original with the integrated filter, looked new, but had been siting for years.

Second was a Precision brand from Oreilly, lasted about 50 miles. Then went with a Carter. lasted maybe twice that.

Looking for suggestions on a reliable brand. I would like to stay mechanical.

The tank has been cleaned, the lines are clear and I have a filter before the pump. The sending unit is new as well.

So what kind of failure,,,,no gas to engine,,,,maybe float stuck or rubber hose to pump collapsing,,,,worn cam lobe,,,,,was there no gas flow when removing line from carb and cranking engine or did the pump arm look damaged.....just looking for clues .....I guess you could hide an electric pump before the mechanical as a last resort .

Float , needle/seat are good. No visible gas in filter before pump. New rubber line everywhere its needed.
No pump arm damage, cam lobe good, you can feel resistance when installing new pump. Runs great with new pump until it fails.
No flow of gas when cranking with fuel line off. No suction from pump.
Steel line from tank to pump is clear.

Im sure if I put another pump on, it would fire right up.

I guess it is possible that the new pumps have been sitting on the shelf for 40 years and the diaphragms gave out,,,,,,

I'm no proponent of parts quality now-a-days, but 3 in a row is a bit suspicious. I bought a small,( 1 gallon) plastic fuel tank years ago that I use for diagnosing. You can pick one up on Amazon, search for small engine fuel tanks. find a nice place to sit it, and run a fuel line to the pump. And see what happens. If the problem is before the pump, this will eliminate the pump being the issue. Over the years I've had many tank and line issues, the worst one was caused by an idiot that thought using clear silicone to seal the sending unit on an F100 was a good idea, a long snake like piece was swimming around in the tank and would eventually get sucked up the hose and kill the engine, when it died the owner would have it towed home and by the time he got to look at it, the snake would slip back out of the tube and show no problems, after it happened about 3 times over a few month period he gave the truck to me. Cheapest fix I have ever done.

My typical diagnosis is to check fuel line from tank for flow, and if it doesnt, I will use compressed air to blow both directions. I do have a clear filter before the pump, so I am able to see if fuel is being pulled. My carb needle/seat/float is good.

I will also use a separate fuel tank and see if the pump will pick up from that, along with priming it.

I will remove the sending unit and check the sock.

I will remove the pump itself and bench test it.

I will let it sit after the initial failure and make sure its not vapor lock.

The pumps were three different brands, but each one failed. It now has an electric pump.

Worked on a 1981 Jeep recently and had three pump failures, finally went to a Omix-Ada brand and it seems to be lasting. The failure pumps were Precision brand.

Also worked on a 65 Chevy G10, its problem was a worn camshaft pump lobe.

How full was the tank when each pump failed?....
The downspout in the tank is metal and can rust through and when that spot on the tube is above the fuel level in the tank, the suction is lost....
Also, any leaks along the line may not be apparent because the line is under suction rather than pressure.....
For filtering, I always install a mercruiser style aftermarket spin-on filter housing as close to the tank as possible and mounted low.... These filters are very small micron rated, but have enough capacity that I've never had one clog and they have eliminated any crap from getting past....I even use them with TBI....

Another mistake I see often that probably doesn't apply to your situation.....
An inline filter does not belong between the pump and the carb......BECAUSE....when they clog, the fuel coming from the pump gets backed up, causing it's check valves or diaphragm to eventually fail....
The small filter in the carb inlet is spring loaded to allow bypass, when clogged, to prevent the pumped fuel from backing up against the pump.....These filters should be cleaned (if sintered bronze) or replaced (if pleated paper) regularly to keep small particles out of the carb...

Tank was either full or half full. Tank was removed before any of the failures and cleaned and prepped. New sending unit, rubber lines etc. Steel lines are intact with integrity.

I did use a separate fuel tank to test the pump, so tank was eliminated as a variable.

I still suspect the lines leaking suction somewhere because "even if" the pump stopped pumping, I would expect the line leading up to it to retain fuel....Maybe re-inspect the draw-pipe for cracks or possible perforations anywhere it's spot welded......
A Holley electric red pump is a bit noisy, but mounted low near the tank, should give you years of trouble-free service and pressurizing the fuel line ahead of it (instead of suction) prevents vapor lock and makes leaks obvious.... They do need a good filter before the inlet, though....

I use Carter pumps, much less noise.

If I use a separate fuel tank, eliminating the truck tank and the pumps fails to pull fuel, then it cant be a leaking draw pipe.