i have a '66 F100, stock 352 with stock carb. a while ago i replaced the mechanical fuel pump with an electric pump. no problems with it at all. but, after i had idling issues (which got remedied) i noticed that the truck would start and run for maybe 30 seconds. i kept starting it, it would idle nicely for 30 seconds or so and then shut down. i got curious and removed the top of the carb. sure enough, i was emptying the fuel bowl without it being filled. i noticed that the fuel gauge was not reading, either. i tapped the adjustable fuel pressure regulator and it started to fill the bowl.
this leads me to believe the regulator (a cheapie, chinese made) no longer works. hey - it lasted a year, which is about right.
here's where i'm going with all of this: i bought a holley adjustable regulator. it is sized for a 3/8" fuel line. i know our stock fuel lines are 5/16".
does anyone have an idea of the fitting adapters i would need for this setup to work? the 3 inlets on the regulator are all 3/8" female. i guess i would need a 3/8" plug with a 5/16" adapter of some kind.
i am totally lost when it comes to hard line sizes and fitting sizes.
can someone please point me in the right direction?

 

a quick search on Amazon for “5/16 to 3/8 fuel line adapters” yielded a lot of results.

Could also buy a 10ft Evil Energy -6AN (3/8”) kit and replace the hard line.

or, just before the regulator go from hard line to 3/8” hose then into the regulator with a barbed 3/8” fitting. (3/8” hose will fit over and seal against the 5/6” hard line no problem. Hose clamp it.

 

o.k.....i feel like an idiot. i've typed in everything except that phrase on amazon. i did that search on a vendor's site (can't remember who's it was) and came up with nothing.
i'm gonna go back to amazon and search that.
i'll shut up now

edit......i did see some of those adapters at some point. what i was asking for was adapters for hard lines. a 5/16 steel line going to, say, a 3/8 plug screwed into the regulator. part of my problem is that i'm not up on the terminology to know exactly what to ask for.

 

You should be able to get a simple adapter between the two.
Looks like holleys are 3/8 npt.
Is your line 5/16 flare?
Do a broader search. Something like this?
You can possibly find this adapter type at a local auto parts store.
​​​​​​​I would not suggest adding hose to bridge the gap. Metal is much safer for fuel delivery.

 

Inverted flare reducer.

https://www.summitracing.com/search/part-type/fittings-and-adapters/fitting-category/inverted-flare-to-inverted-flare

 

yes, the stock line is 5/16" flare. i do have hose right now. i used it as a band aid to "get me by" but now, i want to install all hard line.

i need to go back to school to learn the proper search phrases. you guys are awesome with these suggestions. i did consider 8lines suggestion about the evil energy kit, but as i said, i want to go back to steel line.

 

[QUOTE=ramrod66;21230781i need to go back to school to learn the proper search phrases[/QUOTE]

I’ve always thought it would be great if some member, one who has a foot in both worlds, could publish a Southerner to Yankee Translator. I’d buy that.

 

Y'all gonna need onea them.

Ramrod
Unless you bought a super dupper drag race fuel pump it likely won't need a pressure regulator. But if you think you need one get a Holley 12-803. You don't need to know any search terms. You can get everything you need including the regulator at NAPA or O'Reilly's. They all keep inverted flare hard line in different lengths with fittings on it and they have any adaptors you might need. You might have to buy yourself a tube bender to plumb everything up.
There is a reason the factory didn't use anything but hard line on the pressure side of the pump. There is a thread that I can't find where another member's truck burned because of a failed rubber line.

 

Found it! The reason to not have rubber fuel line on the pressure side of the pump. Disaster strikes! - Ford Truck Enthusiasts Forums (ford-trucks.com)

 

that rubber line was between regulator and carb. so reduced pressure.
sounds like owner was just a little off with alignment.

 

thank you for the input, cropduster. i do need a regulator with my fuel pump. it's regulated down to 2.5 psi with the cheap adjustable regulator that just failed. i had it up to 4 psi and fuel was geysering out of the bowl vents. i couldn't believe it.
i should have checked one or more of the auto parts stores to see if they had anything that worked for me. i do have a tubing bender and flaring tool to install the hard lines.
the rubber lines make me a bit uneasy.

 

I’m curious why you went with an electric fuel pump. 🤔

 

When I bought the truck, the PO said "this truck eats fuel pumps". The mechanical pump that was on the truck at the time was not working. When I got it home, I bought a new mechanical pump and installed it. It.didnt work. I assumed that the eccentric on the cam was bad, broken or whatever. It takes very little motion of that eccentric to make the pump work. Considering that the truck had a history of mechanical pumps either not working, or working sporadically, I simply bypassed the problem with an electric pump.
the truck had seen, I believe he told me, 3 mechanical pumps in the 73,000 miles of its life. Kind of unusual.

 

👍🏻 thanks for the explanation.

 

Either the pressure gauge is way off, or you have a problem with your carb. The carb should handle fuel pressures up to 7 psi. I could be wrong about some carb brands, but 4 psi shouldn’t cause the carb to leak.