Need help soldering (not electical)

[Crazcnuk]

Fuel injection rails are usually considered to be 'high pressure', which is why I suspect it's designed for an ORB (o-ring boss) fitting.

[81xsproject]

Again; It originally had no threads. It had a brass/copper plug that was probably pressed in. I drilled this out. The only threads are ones I put there. The elbow I bought at the hardware store. I am going to try the fuel tape a couple more times and then go to the fuel tank epoxy.

[vincer]

What about just using some pipe dope. I dont know that much about it as far as if the gas will break it down, but I know the plumbers use if for natural gas and propane lines on black pipe.

[JMF]

You said it only has a few threads when it goes on. That means you have mismatched threads. go to a hydraulic place and they will be able to correctly ID what you have and tell you what you need. If it's strait thread you will have a washer or an O-ring. If it's a tapered thread then all you need is Teflon tape or Loctite thread paste. It comes in a white tube and this stuff seals very well. Use this paste sparingly . Too much and it can get into the fuel system and clog something up. If you use the teflon tape, all you need is the plain ol white tape.
I'm retired from the petrochemical industry as a machinist and we used the plain white tape for everything. The most I worked with was about 900 PSI and with all grades of gasoline, acids, caustics, oils, acetone, mek, mibk,ipa,toluein etc..
Find out what you have and you'll be O.K.

[JMF]

What tap did you use? Was it a straight tap or a pipe tap? and what size?

[fredintoon]

Drop the other shoe?

It originally had no threads. It had a brass/copper plug that was probably pressed in. I drilled this out. The only threads are ones I put there. The elbow I bought at the hardware store

Hi XS,
what thread did you cut into the end wall?
(Tapered pipe/parallel pipe/other?)
How thick is the end wall that you tapped into?
(If the end wall is thinner than ~3/4 of the thread diameter a tapered pipe thread will not seal.)
What thread is on the hardware store elbow fitting?
(Tapered pipe/parallel pipe/other?)
Those hardware store fittings come with several lookalike thread forms.
Tapered pipe to tapered pipe will only seal with thread tape if the depth of engagement is sufficient.
Other thread combinations may screw together but thread tape can't make them seal.
Or, as you say, "Buggrit, epoxy rules here!"

[renegade_xs11g]

The elbow only lightly threads in. I was very surprised that the yellow fuel tape didn't work.

Well, I think that's the issue....lightly seated....
that elbow is more than likely NPT, 1/2" maybe? size really doesn't matter
but you may have tapped the wrong size? or maybe too deep?
NPT threads are kinda picky like that
Brass fitting into aluminum, calls for teflon tape, the white stuff, but the yellow tape you used should be ok......it's all we used, worked as a pipe fitters apprentice for a while,
(well it was one of many things I did while working for an Automation Machinery Manufacturer)
Hydraulics, Water, Sand, Air, name the application, that's what we used
BUT, NPT requires torque

should be easy enuf' to fix....grab the tap you used, Find a 'Parker' store...yellow pages, Hydraulic Fittings & Hoses, or maybe the local hardware

or JBWELD,
Good Luck