Well there you go. Sounds like you got a new fuel pump with a bad pressure regulator in it. AKA Defective. Take it back and warranty it. You shouldn't have to put a restrictor in line permanently. The regulator in the pump ( as seen in Rich's video) is supposed to do that. Rich mentioned it just as a test.
So the air test showed the needle and seat sealing under lung pressure. Which would mimic fuel "under normal pressure". And your float is adjusted correctly. That leads to my 3rd possibility. And Mike's Carburetors warned of it also. Defective fuel pump.

 

Most old vacuum gauges double as a fuel pressure test gauge.

But got a have all the small attachments to be able to do it.

Those old regulators dial in adjustable fuel regulators that came out in the 70's worked pretty good for a cheapo fix about 3 bucks then.

I know I've still have one or two in an 1lb coffee container that were easy to install
I'd set it at 4 lbs on a el cameo 396, tow vehicle, I had. It did seem like, I notice it was a little lead on power set at 4 lbs

Orich

 

Sounds kind of like fuel pressure is erratic and all over the place, so trying to set the correct float height is a moving target. At some point it floods.

Sent from a pay phone

 

I'm thinking the fuel pump's internal pressure regulator isn't having a hard time sending gas to the carb. But it is having a hard time keeping the pressure where the needle and seat can cut off fuel flow when the bowl is at the correct fill height. Driving down the road when the carb is using more gas the problem isn't so bad it sounds like. But then at idle afterwards when the carb doesn't need that much fuel flow the pump is still pumping closer to what it was when the truck was at speed. I say take the pump back to where you bought it and have them replace it under warranty. They like to spout out "lifetime warranty". I'd have them use it.

 

Also while still pushing junk into the carb, this can happen if not real carful or caked into the fuel line if this truck has been sitting for a couple yrs.

I think we've all kind of been through this problem at lease once when we were in are teens being young dumb.
Like chasing a mouse with old rubber gas line leaking to sucking air mess up needle seat.
Orich

 

After reading thru this post I keep wondering about the float height. If we adjust the float arm by bending or moving the float down doesn't this raise the gas level in the bowl and vise versa? Or am I on crack?

 

If you push the float down with the float/needle/seat/carb lid assembly up side down (closer to the under side of the lid) then, yes, you raise the fuel level. You see. the float is suspended from the carb's lid. Opposite of a Autolite 2100 2V. The Autolite 2100 is the only carb I know of that the float,needle, and seat are attached to the carb's main body. Which is why it's the only carb that you can take the lid completely off of it when the engine is idling.

 

Ok guys, I got it, finally figured out what was going on and as a result, I haven't been back until now to tell you about it because i've actually been out driving the truck

I did replace the fuel pump with a new unit because I liked the theory of it overpowering the needle and seat, however, that did nothing for me.

The problem was little chunks of rubber hose coming through the fuel lines. I had ruled that out both because I already replaced all the rubber lines and because I have a clear filter before the fuel pump and, of course, the fuel pump has a canister filter in it.

But rubber chunks were still getting through both of those filters! In fact, in between the fuel pump and carb I switched to a new rubber line so I could run yet another (now 3rd) fuel filter, this one is a 100 micron filter. But even with three filters I placed the fuel line in a clear cup and turned the engine over to reveal rubber chunks in the fuel. They were smaller but still in there.

I took the top of the carb off one night and found a big chunk of rubber on the seat, cleaned it off and drove it maybe 10 miles. Gas spilled over the carb again, so I took the top back off and there were tons of little chunks of rubber on the seat again!

The only way i've been able to drive the truck these last two days is by replacing the cheap $2 clear filter before the pump when it collects about a tablespoon of rubber chunks. Every time I replace it the truck runs longer in between replacements and I may be on my last or next to last one now as the rubber is disappearing.

I can't possibly understand how rubber chunks get through three filters, especially a 100 micron one. I could understand if filters were getting plugged but they weren't, they were just not working. My closest guess is that the bunch of rubber in the pre filter was getting churned up in there while fuel was flowing making those chunks smaller, then they did the same in the canister filter and again in the 100 micron and they passed through. Still seems like filters are just junky though...

Anyway, thanks for all your help, very excited to be racking up miles instead of disassembling the carb every day

Orich was right, little pieces of rubber can make you crazy!

 

But you're getting so proficient!

*ducks*

 

100 Micron is too large! Try going to a 5 or 10 micron filter. Raycor makes double filter set, used on boats, you could use a 10 for the primary and 5 for the secondary. But glad you found the problem.

 

2x Graykip 100 should be like the first then down to a 10 micron filtration.

I know many people get this back~*** words way of thinking that 100 microns is smaller.

Any way good to hear you've found what was not right, but where is the rubber chunks coming from???

I've seen where the rubber gas line sheds little bits of rubber that made it's way into the carb was every time any you remove an re install old rubber gas lines it can sheds little bits that find it way up into carb needle seat.

If a guy makes a rough cut with like a hack-saw and don't file down the barbs good even a new rubber gas line with a cut steel gas line can rips the inside a rubber gas line that can send bits of rubber into the carb. So this gets repeated with the carb being flooded if a steel gas line has a badly rough cut end when installing a extra filters.

Just sayin:

Orich

 

Glad you found the problem. And warrantying the pump didn't cost you anything. 2X Orich. Where's it coming from? Are you sure you replaced "All" the rubber lines? You might follow the path of the fuel all the way from the nipple on the gas tank sender all the way forward. The PO might have installed a piece of rubber hose somewhere that Henry didn't. All kinds of weird things get and got done to these ol' rigs. Or it's in the tank.

 

Man, i'm good now. I can remove the top of the carb, clean the needle and seat and have it installed and the truck running in five minutes! But I have a bruise on my chest from leaning over the radiator so many times, lol

That is a good tip, I actually had no idea how the micron rating goes. Not a clue. Now I know.

I think the rubber must just have been stuck to the inside of the metal lines. I can't think of anywhere else it could have come from. I didn't cut any metal lines and the rubber lines I cut with shears that were very sharp so the ends were smooth.

 

A possibly that the 4'' short rubber connecting hose cab filler pipe an the tank has started to crack an shed bits of that hose from the E85 stuff we now have to use.

If the inner sock on the in-tank fuel pickup filter tube has started to crack or break apart letting stuff pass through it an passing it on to the carb..

Just satin!
Orich

 

Just crazy man, glad you are getting it back in gear, thought only weird stuff happened to me......