Will the Gas Drain Out

[Larry M.]

The gas tank in a midyear looks to be mounted fairly high. If you disconnect the gas line at the input to the fuel pump will the gas drain from the tank....do you have to plug the line?

It seems to me that if you want to replace the flex hose there is no good way to plug the line while you work.....but I'm guessing that there is a simple trick here that you guys know.

[Joe L.]

Re: Will the Gas Drain Out

The gas tank in a midyear looks to be mounted fairly high. If you disconnect the gas line at the input to the fuel pump will the gas drain from the tank....do you have to plug the line?

It seems to me that if you want to replace the flex hose there is no good way to plug the line while you work.....but I'm guessing that there is a simple trick here that you guys know.

Larry-------


YES, it will DEFINITELY drain out when the flex line is disconnected at the fuel pump. There are several ways to prevent this. First, you can use a pinch clamp on the flex fuel line prior to removing it from the pump. If you want to replace the flex line at the same time as the fuel pump (which you always should), then install the pinch clamp on the new line, remove the old line and quickly install the new line with pinch clamp pre-installed.

You can also install a pinch clamp at the flex line from the fuel sender and pick-up. This will stop the flow of fuel from the tank into the frame line. However, when you remove the flex line at the fuel pump, some of the fuel in the line will drain out, so be prepared to catch it.

If you wish to replace the flex line from the fuel sender and pick-up (which should also be done periodically), then you must drain the fuel tank first.

By the way, I use only modern, fuel injection 3/8" rubber fuel line to replace the the flex fuel lines. This has a material formulation that is compatible with modern-day gasolines and is very high quality.

[Michael J.]

[Terry M.]

Re: Will the Gas Drain Out

In my foolish youth a used spark plug worked just fine to plug the fuel line.

[Larry M.]

Re: Will the Gas Drain Out

So, for a 64 model is that a top-tank outlet which siphons? If it is then the post above makes a lot of sense to me.

[Joe L.]

Re: Will the Gas Drain Out

So, for a 64 model is that a top-tank outlet which siphons? If it is then the post above makes a lot of sense to me.

Larry------


All 1963-74 Corvettes are BOTTOM outlet. The fuel will flow by GRAVITY and not siphon. A siphon would be applicable to 1975 and later Corvettes, definitely NOT 1963-74.

[Terry M.]

Re: Will the Gas Drain Out

Larry------


All 1963-74 Corvettes are BOTTOM outlet. The fuel will flow by GRAVITY and not siphon. A siphon would be applicable to 1975 and later Corvettes, definitely NOT 1963-74.

Damn, and I was just about to throw out all my used spark plugs.

[Larry M.]

Re: Will the Gas Drain Out

Thanks a lot Joe. I thought I knew that the pick up went in from the bottom but I wasn't sure it was gravity. Sounds like you are sure and I'm going to go with that.

[Timothy B.]

Re: Will the Gas Drain Out

Another thing I have done if the fuel level is low enough in the tank is to jack the passenger side of the car up high. The fuel will run to the drivers side and allow you to change the hoses.

[Kent S.]

Re: Will the Gas Drain Out

Another thing I have done if the fuel level is low enough in the tank is to jack the passenger side of the car up high. The fuel will run to the drivers side and allow you to change the hoses.

That's the way I just did it when changing the fuel sending unit on my '63.

[Duke W.]

Re: Will the Gas Drain Out

Larry-------



By the way, I use only modern, fuel injection 3/8" rubber fuel line to replace the the flex fuel lines. This has a material formulation that is compatible with modern-day gasolines and is very high quality.

Conventional low pressure fuel hose (SAE 30R7) is perfectly fine. It is formulated (since the eighties) to resist degradation from modern ethanol laced gasoline formulations. "Fuel injection" hose (SAE 30R9) is thicker and less flexible because it is designed for EFI systems that typically operate at about 40 psi. Conventional fuel hose is designed for the lower feed pressure of carburetor fuel systems. The hose from the frame pipe to the fuel pump inlet doesn't really see any pressure, but deteriorates from engine heat, which is why it should be checked regularly and changed if it shows any evidence of deterioration.

Clamping the old and new fuel hose is a good idea, but put a bucket under the area to catch any spilled fuel and have a helper standing by with a fire extinguisher.

Here's a war story about this hose.

From late 1971 to early 1975 I stored my SWC in my parents Seattle garage while the Air Force had me at Grand Forks AFB. I drained the fuel tank, so one thing I had to do when I picked up the car in March 1975 after moving to California was add gasoline. After adding about three gallons I noticed fuel dripping from around the fuel pump area and found that the hose (which was original (12 years old and about 110K miles) had a split and was seeping fuel.

I removed the hose and plugged the frame pipe with my finger while my dad took the old hose down to a local gas station (that happened to be owned by a high school classmate). So for about the next 15 minutes I played Little Dutch Boy plugging the dyke with my finger to hold back the flood.

When my dad returned with the new hose cut to original length and a couple of new clamps loosely over the hose, I shoved one end onto the fuel pipe with my free hand, then slid my finger off the frame pipe as I shoved the new hose on. Very little fuel was spilled.

Everything went fine from there. Even the battery that had been sitting in the basement for the entire time accepted a full charge. I added some fuel to the bowls through the bowl vents and the engine fired right up as if it had only been sitting overnight.

A design like this would never pass muster, today, but one advantage is that if you need to drain the fuel tank, attaching a 3/8" drain hose to the front fuel pipe is a quick and easy way.

So everyone should ask: How old is that fuel hose? At least you can give it a good inspection, and if you don't know how old it is, maybe you should buy a new length and install it the next time the fuel tank is near empty. It's only a five minute job and a good ounce of prevention because if that hose starts to leak, the entire contents of the tank will eventually drain out!

After you replace that front hose, think about removing the spare tire carrier and checking out the tank to frame pipe hose. It will last longer than the front hose because it doesn't see heat, but a break will also allow the entire fuel tank to drain.

Duke

[Timothy B.]

Re: Will the Gas Drain Out

Just last summer I replaced the tank hose on my 67, the hose did not leak but was so hard I could not squeeze it together.

It's the best maintenance you can do on these old cars.

[Paul J.]

Re: Will the Gas Drain Out

If you slip your thumb over the end as you're working the cork in you'll have very little leakage. I use old plugs and caps that come with rebuilt parts. These work quite well.

[Joe L.]

Re: Will the Gas Drain Out

Just last summer I replaced the tank hose on my 67, the hose did not leak but was so hard I could not squeeze it together.

It's the best maintenance you can do on these old cars.

Timothy-----

Yes, when the hose gets like this it's way past time for replacement. And, as you found, when the hose gets like this there's no way you can use a pinch clamp on it. It will break. When the hose is supple and new, the pinch clamp won't hurt it.

[Paul H.]

Re: Will the Gas Drain Out

In my foolish youth a used spark plug worked just fine to plug the fuel line.

It's always worked for me as well Terry I guess I must have a little "Bubba" in me. Narrow end in first until it seats at the thickest point.