If he just clamped the new line on the old fitting I bet it's sucking air there.
Don't bother with a draw straw. Save your money, run the tank low on fuel and put in a sump. The straw will suck air under a 1/4 tank, everybody says so, and they are right! I could watch my fuel pressure drop from 14 to 2 or 3 sometimes when I got on it, it was scary to watch.
I filled a 5 gallon can with fuel, ran the tank down to an 1/8 or so, then siphoned out all I could. I got about 8 gallons from it. I then jacked up the back of the truck as high as I could and put it on stands. (safety 1st!
)I located a spot behind the sender module where it was mostly flat, drilled the hole and filed the edges. I got a Sinister Diesel sump, and it came with a gasket. Throw the gasket away, tell you why later. I figured which direction I wanted the line to go, the drilled for the mounting bolts. I drilled 2 across from each other, then put the bolts in, and drilled the rest while holding the sump in place so all the holes would line up when I was done. I then installed the sump with the gasket.
Now here is where it went bad......
A year or 2 later, I knew the gasket had been swelling because I could see it pushing out around the sump. The truck had been sitting out back for a month because I was driving the truck with AC. I jumped in, started it up, and the gauge showed empty! I pulled up by the house, pulled the line and drained the tank. (still got about 5 gallons from it) I jacked it up and pulled the sump, cleaned off the gasket goo, which must have been made of rubber. I went and bought a tube of Permatex Black RV, closest to fuel resistant I could find. I then reinstalled the sump with a nice film of RTV. (notice I didn't say fat bead!)I left the line off over night and close to 24 hours before I put fuel back in, and it's been fine since. I check it regularly too.
Some sumps have an o-ring, I think I would still put a film of RTV on it.
Sorry it was so long, but I wanted you to know what can and does happen.