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71 Coupe. Frame off restoration. ZZ6 EFI (Edelbrock ProFlo4 58PSI EFI). Tanks Inc. TM33D-T-Kit Fuel tank.
Tank to EFI rail feed
Earls Auto-Flex Braided Stainless Steel with -6AN fittings. 10Micron filter and fittings inline. EFI rail to regulator return to tank
Earls Auto-Flex Braided Stainless Steel to 3/8 stainless steel hardline using Earls tube adapters.
Before putting the body on the frame for the last time for this restoration, I want to test the fuel system for leaks. I don’t want to have to mess with leaking fittings after everything is cramped including the potential to have to pull the tank because of a bad fitting on the pickup.
Is there an alternative to gas for testing so as not to stink up the shop or leave the fuel in the system for a few months? Or could there be another ingenious way to do this testing?
Fragola and others sell a leak check kit for AN fittings. It’s a plug on one side and a schrader on the other. You can inflate the hoses a bit past your target PSI and put them in a bucket of water to see if the ends leak.
You could also mock the whole system up off the car and check for leaks once you’ve individually checked hoses. For me, the AN fittings were the primary point to check. Throttle body I checked on the motor.
2020 Corvette of the Year Finalist (performance mods)
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you can just use 2 gallons of gas and energize the pump. You'll see the leaks at 60 psi. then just disconnect it at the Sniper and pump it into a can or use fuel stabilizer in the 2 gallons and leave it in the tank. It wont help with the smell while testing but you shouldnt be able to smell it in a closed system
I connected the -6AN ptfe lines that I made together at each end and pressurized them with 100 psi of air and let it sit overnight. Perfect, not even a tiny hiss. This was on my C2, but same principle.
One quick disconnect, a 1/4 to 1/8 npt reducer and -6AN coupler with a 1/8 npt gauge fitting. I ran two 3/8” stainless lines (this was before the Holley fuel module was available) in the stock location, flared the ends, and fabbed up two braided ptfe hoses at the back that connect to the tank. Used the doohickey from the first picture to join the hoses at the front and compressor on!
Seeing that picture sure makes me appreciate the Holley OEM Fuel Tank Modules. I bought one and installed it in less than half an hour (has the Hole on the bottom of tank) from start to finish and it supplies 60 p.s.i. to my Holley Sniper Stealth EFI system The unit has the new fuel gauge sender and the Fuel pump and internal fuel pressure regulator all in one easy to install kit. It takes one hose to supply the fuel needed and that is all. No return to deal with, it makes for a very clean and simple installation.
The EFI system is installed on a 12.25-1 Compression ratio 427 and really makes life better as it starts easily and runs smoothly. It even handles my water/methanol injection system for me along other things and it still sounds like a ferocious engine even with the EFI system.
Great tool there Factoid! That might be something I have to put together as it could be handy testing the hoses I make.
Thanks boys! I never thought of compressed air to find leaks in the hoses nor that there were out of box test kits to do this. That’s why I belong to this forum!
The only fittings that I am really worried about leaking are the “braided to hardline tube adapters” which I can test ahead of time with compressed air (thank you Shark Racer and Factoid), and the “1/4 NPT to -6AN fittings” at the tank pickup which I might just have to run the pump with gas and stabilizer (thank you Rescue Rogers for reminding me of stabilizer that I use in all my motorcycles and boat every fall, doh!)
I’ll test everything I can with compressed air ahead of time so there is less potential mess when I run fuel through the system for the full test.
71 Coupe. Frame off restoration. ZZ6 EFI (Edelbrock ProFlo4 58PSI EFI). Tanks Inc. TM33D-T-Kit Fuel tank.
Tank to EFI rail feed
Earls Auto-Flex Braided Stainless Steel with -6AN fittings. 10Micron filter and fittings inline. EFI rail to regulator return to tank
Earls Auto-Flex Braided Stainless Steel to 3/8 stainless steel hardline using Earls tube adapters.
Before putting the body on the frame for the last time for this restoration, I want to test the fuel system for leaks. I don’t want to have to mess with leaking fittings after everything is cramped including the potential to have to pull the tank because of a bad fitting on the pickup.
Is there an alternative to gas for testing so as not to stink up the shop or leave the fuel in the system for a few months? Or could there be another ingenious way to do this testing?
Thank you,
Richard
When I installed my LS3 I installed new fuel lines down the driver side of the car. I tested both the supply and return lines using air , but I also installed a pressure gauge, and shutoff value to disconnect the air compressor.
Let it see if the pressure held for 7 days. This is showing me testing a brake line, but I used AN6 adapters to connect to fuel lines. I was thinking the same as you, didn't want to fix after the fact. This saved me a lot of time since I did find leaks using this method.
When I installed my LS3 I installed new fuel lines down the driver side of the car. I tested both the supply and return lines using air , but I also installed a pressure gauge, and shutoff value to disconnect the air compressor.
Let it see if the pressure held for 7 days. This is showing me testing a brake line, but I used AN6 adapters to connect to fuel lines. I was thinking the same as you, didn't want to fix after the fact. This saved me a lot of time since I did find leaks using this method.
Brilliant! I didn't even think about testing my brake lines as well, prior to body going back on frame.
I'm going to build a "cagotzmann multi-tool" and report back...
Brilliant! I didn't even think about testing my brake lines as well, prior to body going back on frame.
I'm going to build a "cagotzmann multi-tool" and report back...
Cheers,
Richard
I connected to the MC Line with brake calipers / pads / rotors installed, So the calipers would be activated. Left them for days to make sure no leaks at all. Only pressure drop was due to tempature changes. Colder = lower pressure or warmer = higher pressure.
I connected to the MC Line with brake calipers / pads / rotors installed, So the calipers would be activated. Left them for days to make sure no leaks at all. Only pressure drop was due to tempature changes. Colder = lower pressure or warmer = higher pressure.
I was going to ask if you had everything connected for the brake test…
How many PSI did you use on the brake system for the test?
And if no one has mentioned it yet, those aluminum AN-6 flare fittings can't take much torque. Proper torque is 12-15 ft/lbs IIRC. Steel can take a little more. I went too tight on the Mechanical Pump fitting and it started seeping. Natural thing to do is "tighten it up to stop it". WRONG!
Just keep torque in mind.
After installing some AN fittings, for my EFI pump, between the rear deck and the top of the gas tank, and wanting to eyeball then --- I bought one of those cheap endoscope cameras and hooked it up to my phone..... well, and my laptop also. Something to consider... handy or lots of other inspection things also.
I picked a easy number on the Gauge. Easy to see if it moved. I used for the GAS 100 psi and 120 for the brakes. My compressor maxed out @ 125.
Thank you!
Originally Posted by Cavu2u
And if no one has mentioned it yet, those aluminum AN-6 flare fittings can't take much torque. Proper torque is 12-15 ft/lbs IIRC. Steel can take a little more. I went too tight on the Mechanical Pump fitting and it started seeping. Natural thing to do is "tighten it up to stop it". WRONG!
Just keep torque in mind.
Steve
Originally Posted by carriljc
After installing some AN fittings, for my EFI pump, between the rear deck and the top of the gas tank, and wanting to eyeball then --- I bought one of those cheap endoscope cameras and hooked it up to my phone..... well, and my laptop also. Something to consider... handy or lots of other inspection things also.
Testing EFI Fuel System for Leaks
