VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Temporary fuel line plug

Years ago I put an in line filter ahead of the pump on the 38. I cut the hard line and used short rubber hose to splice in the filter. Now that I have a new tank and an in line filter just ahead of the carb I'm planning to remove the filter ahead of the pump and patch the hard line. I'll need to temporarily plug the end of the line from the tank while I replace the rubber hose with the metal. I'm trying to decide what would work best to staunch the flow of fuel will still allowing a compression nut & ferrule to slide over it. I'm thinking about maybe cutting the head off of an old wooden golf tee. Ideas?

Hi Tiny,

Maybe a ‘38 coupe fuel tank set-up is not like my ‘37. Mine had a right angle shut-off valve on the outlet port of the tank.

The golf tee will work except you need a way to remove it. If you cut it to a small diameter so you can slide the ferrule over it I am not sure you can remove it.

What if you take a short piece of 5/16” dowel and cut a long taper on it?

Another idea would be to figure out how to pull a light vacuum on the tank. Or at least seal the filler so only so much gas will run out.

Or you could shove a golf tee into s short piece of 5/16” hose. Have it ready to slip over the end of the hard line after you make the cut. Get everything else ready and then pull the hose while you slip the nut and ferrule over the line to make the last connection.

The shutoff valve would be handy but I had to remove mine because the jam nut was split and I couldn't find a replacement. Until I solve that issue it's a simple nipple & ell arrangement. I just measured the ID of the line and it's .23 so I can probably take a short piece of .25 dowel and taper the end. I'd just hate to get in the middle of the operation and have my plug method prove to not be adequate.

Interesting that I had a similar failure on the shut-off valve on mine. The packing nut split. I replaced it with a quarter turn valve.

A suggestion - why not empty the fuel tank after parking the car on a slight uphill slope, then remove the fuel filter. The amount of fuel spilled will be negligible as the fuel in the line from the tank won't flow uphill and there'll be no pressure on it from fuel in the tank to push it uphill.

Good tip, thank you. While it's pretty flat around here I do have a floor jack and can raise the front a bit. One possible downside is I may have to stand on a box to get to the line if I raise the front very much. I currently have a half a tank so I'll need to burn some off before trying that.

Must have been a common issue. That particular synapse refused to fire so all I could come up with is Jam Nut. Of course it was the Packing Nut that split.

Got it done today. I took a short length of 1/4" dowel, ran one end through our pencil sharpener and tapped it into the end of the line when I removed the old filter and hose. It worked great. Below shows the patch while drip checking and the piece of dowel. I had one slow drip on the far aft connection that required a tad more tightening.

It seems the aft connection drip is being difficult to stop. I'm almost as tight as I dare to go. I may be forced to try again.

Yes, those compression fittings can sometimes be a challenge. It seems like there can be problems with the sizing and shape of the ferrule as well as the seat in the male fitting. Despite what people say you sometimes need to use a little bit of sealant.

I used a slightly different approach with my ‘37. I needed to replace the line from the tank when I was getting the car back on the road. The limitation I had to deal with was that the longest 5/16” fuel line I could find was 60”. That was not long enough to reach from the outlet at the tank to the fuel pump.

So I had to bridge a gap similar to what you have. I simply used a length of 5/16” fuel hose and 2 spring clamps. There were no problems with leaks and it allowed for engine movement without flexing the steel line and connectors.

I was wondering if loosening the nut and packing around the ferrule with pipe dope then resetting the nut would be effective. It isn't much of a leak, just an occasional drip.

If you can, twist the old ferrule loose and remove it.
Then just install a new one.

If you can't, then hopefully you can find an "S" in the line somewhere that can be straightened a bit to lengthen the line enough that you can cut the end with the old ferrule off.
Then just install a new one. 🙂

I've had to do this before.
A new ferrule will be softer and larger and should do the job.

PS
If the old ferrule has compressed the line to a smaller diameter as sometimes happens,
you will likely have to cut that area off as per the second option above.

PPS
And yes... I've used a little Permatex Aviation on occasion as well. 🙂

I've been fighting this for weeks and I can not get it to stop dripping gas. As much as I hate rubber hose I'm going back to it. I'm done fiddling with it.

I would replace the front two line pieces with one piece. The less fittings the less chance of trouble. With a new line and fittings you will have a better chance of success.