[zeke67]

I would like to check for leaks before starting the engine. The Chevelle has been sitting for over a year. During that time, I replaced the fuel lines between the mechanical fuel pump, regulator, filter and carburetor. These are all double flare aluminum, so I really want to sort out leaks and makes sure the flares are good. I could rig up an electric pump as a "puller", but can I pull fuel from the tank though the mechanical fuel pump?

 

[Johnny O]

I dont think that will work very well, if at all...Electric pumps are 'pushers', not pullers...that's why you always mount them back at the tank and not up front. If you have any leaks at all, how big could they be? Why not just wad up a rag under each joint that you're worried about, and get a friend over there when you start it up. Just see how it looks while it's running. I dont think I would go thru all the trouble of hooking up a different pump and all.

 

[webfoot]

Is the carb dry? If it is just going to idle I would think the fuel in the bowls would last you until the fuel from the tank makes it to the carb.

 

[zeke67]

Good point on "pulling" fuel. I'll have to re-think this.

Potentials for leaks: 11. Sounds like a lot, but each flare nut is a spot and each flare-to-pipe fitting is a spot. Between the fuel pump and the carb is a regulator and fuel filter. Picture of the set-up is here: http://web.mac.com/zemke2/iWeb/Site/The Shop.html.

It IS a lot of trouble, but I didn't want fuel leaks on a running motor and I already have an electric fuel pump set up for transfer fuel between gas cans. (scroll down on the above link to see it).

From the car sitting, I'm sure the fuel bowl is bone dry, but my bigger concern is leaks, not getting fuel to the carb.

 

[Tom Mobley]

if you're careful you can do what I do: I use a an air nozzle, wrap a rag around it, stick it in the filler neck, GENTLY pressurize the tank. this will push fuel to the front, fill the carb and even give a pound or two of pressure in the entire line. That will help check for leaks between the tank and pump.

Obviously, this would not be a good time to do something unfortunate like blow up the tank or something. You can start with a couple small tests, you can feel the air pressure coming out as you pull the rag/air nozzle away, get an idea where you're at.

 

[novaderrik]

with new flare fittings, i always tighten and loosen them a few times to get them to "seat". i've never dealt with aluminum flare lines, tho.
all you can really do is get them tight, fire it up, and fix any leaks as they pop up.

 

[zeke67]

Tom, I may try that, it's easy enough. Anything special you do to plug the vent line? That will push fuel past the mechanical pump? The leak testing I want to do is past the pump.

Novaderrik, I tightened / loosened the flares three times each in a fitting clamped in a vise. I wanted the flares to take set with the line unfastened because I've done this before with the line mounted and it's twisted the tubing. I also grease the nut where it contacts the back side of the flare.

 

[Tom Mobley]

if there's a vent it'll need to be pinched off. I have some small needle-nose Vise-Grips that work well for this.

Yes, it'll push right through the pump. the pump is just two sets of check valves.

 

[1954bigblocktruck]

What I have used when running new fuel lines or priming a new engine for the first fire-up is an outboard motor fuel line with the squeeze bulb on it- like you use for outboards with portable fuel tanks. I just slip the hose over the fuel line back near the tank, and then squeeze away until the float bowl of the carb is filled. This also checks for leaks because you can get several pounds of pressure, depending on how hard you squeeze. Those things are cheap and last forever if stored inside.

On Edit: I forgot to say that I pull fuel out of a 5-gallon can when doin this, but I suppose you could also hook the hose to the tank and pull from there...

Mike

 

[bubba68ss]

i just pulled the fuel line off the carb and kind of 'syphoned' it until i started smelling vapors.
if you fill the bowls up with fuel it will run long enough to get all the fuel up to the carb

 

[zeke67]

Thanks for the advice. I ended up using my electric pump between the fuel line from the tank and mechanical fuel pump. This was I could turn the watch for leaks in real time and toggle the pump on/off easily.

I ended up with one leak -- and it wasn't one of my flares, it was the -AN fitting on the carb inlet line.