OldIHC

4 pages later,,,,,,,does your truck run now?

https://www.summitracing.com/int/parts/ ... /overview/
This is the lift pump that Ram/Cummins chose for their truck and engine combination. Some last for decades and hundreds of thousands of miles. This is very similar to the fuel pump we used on our hot rods in the 1960s. The last one of these I bought came with a pig-tail wire to adapt the pump to a Cummins.
My last electric lift pump on our Ram 2500 came from https://www.bcdiesel.ca/en/fass-ddrp-li ... aqu-8p8haq This pump was very expensive and it works.
I have two of these HOLLEY pumps in my parts drawers. https://www.holley.com/products/fuel_sy ... s/12-812-1 They were on our R120 Diesel. I liked the reliability and instant prime after a filter change. I had one of these pumps on each of two tanks.
While I would not rather walk than use an old technology diaphragm pump, given the choice, well, you know ......................................

The Holley or Carter rotary vane pumps are good pumps, I have no beef with them. Well built and good for moveing a lot of fuel. On an old inline 6 you would really need a return with them as they move a lot of fuel and if you throttle the outlet it will get hot.
You would likely need a fuel pressure regulator and return system if feeding a 1bbl on an old IHC, add all that up plus the cost of electrical safety switches and you are looking at a fair chunk of change. If that's is what floats your boat, than have at it.
For a little more than $100 you can have the stock pump cleaned, rebuilt with newer material and have a running truck if the fuel pump is the problem, if it isn't the problem, electric or mechanical makes no difference, it isn't the problem.
Very small pin holes in the fuel line can be hard to spot, often the rust wick's the fuel and it evaporates and doesn't leave a tell tail stain. If the pin hole is on the suction leg of the fuel line it can cause the problems the OP had.
No matter what type pump (mechanical or electric) it would be worth replaceing the line from the tank to the carb. steel line is cheaper than pulling your hair out wonding why it looses prime or can't deliver under load. Check all fittings esp 90 deg ones for blockage. run a wire thru to the tank to be sure there is no blockage. The biggest electric can't pull thru a blocked line, and starving any pump on the suction side is bad for it.

Remember it is atmospheric pressure that pushes the fuel. A pump moves the fuel along and leaves a low pressure behind. The outside air pressure pushes the fuel into the lowered pressure area.
A very powerful pump is not able to perform any better than the ability of the 14.7 psi at sea-level atmospheric can supply fuel to that pump. Pumps move volume, restrictions make pressure.
This truck hobby can take a ton of time and lots of cash. Isn't that what a hobby supposed to do?

Bedrock, We have decided to rebuild the pump. Will take a week or so to get parts, etc. Will post updates later.
Thanks everyone,
-Snowman.

Read through this entire thread with great interest, enjoying the exchange about mechanical vs electric fuel pumps. I have no strong feelings either way, except to say that I drove a '53 R-110 with a mechanical pump for almost 12 years without a single issue.

I am assuming Snowman got the truck running, but I am curious, did the pump rebuild do the trick, or have you gone to electric?

I was driving my D-2 yesterday and it has started stumbling when going up hills, and stalling. Going to start simple and clean the fuel filter first (not even sure whether the old Durex filter on my truck is original, but appears to be easy to clean the brass porous element within).

John

Pump was rebuilt and is working fine again.

Ah - so it was your pump. Glad to hear you figured it out and are running! I believe I am having different issues - starting a new thread.