"Well I dont really understand the "Do the math comment". What math? I'm simply speeking from experience."
I was referring to looking at the pressure needs of the system and then selecting a pump accordingly. You want 15 PSI at the VP. The carburetor pump struggles to put that out. Other pumps will make 60-80 PSI like nothing. Why not select a solution that give you a 50 PSI increase (that being a different pump) rather than a 2 PSI increase (a different line) ?
Yes, increasing the size of the fuel line will increase the flow to the injection pump. But if you selected a different pump it would push fuel through those lines without any problem at all.
Increasing the line size allows the barely adequate carburetor pump to get a few more PSI to the VP. Say 15 PSI. Replacing the carburetor pump with an EFI pump like a Walbro would increase the pressure to oh... 60 to 80 PSI without a bypass. It delivers so much fuel that you need to provide it with a relief system to limit the pressure, all with stock lines.
Replacing the line is a band aid. Replacing the pump fixes the problem.
"I guess if you want a mathmatical equation then maybe you didnt read the part about 1/8" fuel lines. I dont recall EVER seeing a fuel line that incredibly small on ANY vehicle before (not even a motorcycle), but I guess since you stated that Ford trucks and gassers (theres a general word) use the same size fuel line then OK you are the man of knowledge."
Fuel lines (being steel tubing) is measured in OD. I am not aware of any lines being 1/8" OD on the supply side.
"Oh yea, did I already say that what I said works, cause it does. The problem isnt pressure its volume. The VP actually likes the extra fuel for better cooling."
OK. Leave the stock lines alone, bolt on a Walbro, put on a bypass and see 70+ GPH right to the VP44 inlet. Now which was a better fix ? The bigger line or the right pump ? There is no way the stock pump will ever move 70 GPH to the VP, bigger lines or not.
"And by the way carburated fuel pumps usually dont exceed 7psi. If so then they need to be regulated with a return line at the FP or at the regulator before the pressure drops. Thats funny. Did I say cutting down the pressure before it gets to the carb? Wouldnt that ruin the FP? NO, because the FP wouldnt be running in the bypass mode since it has a return line to keep up the volume. Hey thats something our poor little LP doesnt have untill after the VP. Reason needed for the increased fuel line size to increase volume on the Cummins."
www.holley.com. Lots of their pumps exceed 7 PSI. Yes, they need to be regulated.
"So if in the future you dont speek from experience, not just opinion, then dont be so rude. Thanks"
You might want to read some of the posts on Walbro fuel pumps.