99' fuel pump issue?

[the shadow]

my son's '99 4.0 4x4 has developed a sporatic no start issue (maybe every other time he tries to start it) cranks fine and has spark we here the relay but swapped it out anyway. the truck wont start till you crank it the 3rd or 4th time then it seems to run fine. I did some searching on the site and decided to get a loaner fuel pump pressure tester at he auto store to check the fuel pump. well after hooking it up I turned the key to the run position 3 times, checking the gauge each time to see if the fuel psi stayed the same or bumped up. well after 3 times the gauge was at 0. I started the truck and ran it for 10-15 sec then shut it off, the gauge then read 5 psi. there is definitely fuel at the connection for the test gauge and everything was tight. I believe the fuel psi should be well over 55? so I figured I'd be replacing the fuel pump and ordered one on-line. the only recent work to the truck was an oil change and a fuel filter change last month by a local shop.
my question is how can the truck run on 5 psi, or is it barely running on 5 psi. I have the new pump but before I un-box it and remove the bed to fix it I figured I better see if any of you guys suggest anything else to check or can answer my question on the low psi/running etc.
Paul

[the shadow]

I've been doing more searching on the net on this problem and decided it could be the fuel pressure regulator stuck open and bypassing back into the tank internally? I decided to order the new regulator and replace it while doing a new fuel pump. doing the work myself and trying to get my son back on the road is my priority. Maybe its not the best way to go about it but I have to take out the sending unit either way and I dont want to do it twice. the truck has 145K on it but the engine which was replaced only has 13K on it and the trans was just rebuilt 600miles ago, so its worth keeping going at least until the cab falls off as all the cab mounts are rusting to death and there is no good place to weld new ones in? its a shame because the outside of the truck looks awesome. great paint no dents or dings, the underneith is all rust and rot. it will make a great parts truck to someone when the cab mounts finally go.

[e.fisher26]

I had a 05 ford 500 and had the same issue with the gas going back into the tank, but not the stalling, once it started it didn’t stall. U might have both issues as u suspect


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2004 ranger 4.0L edge