Solution for fuel line draining?

[nymustang]

I feel like I've read about this somewhere before but can't find an answer right now. When my stang sits more than a day (which it does um... all the time) the fuel drains out of the line going up to the carb from the pump. I'm guessing its fairly normal for this to happen but I'm wondering if this is preventable. Mostly because it makes the car a real bitch to start. If I come back a week or two later I need to throw a little fuel into the venturis from a gas can in order to get it to start. Otherwise it just cranks till the battery is dead. Part of my starting problem I suspect is that I need a new carb, the fuel is really old and I need a new gas tank. So I'm not so much worried about starting issues at this point but I am wondering what if anything can be done to prevent fuel backslide. Thoughts?

[gotstang]

There's no way it should be doing this. If the car sat for couple of weeks/months, I could understand it if all of the fuel evaporated out of the carb, but this ain't kosher.

Old fuel is some seriously bad mojo. It will goop up the inside of the carb and can damage the engine if it's bad enough....if your tank has a drain plug, use it. Might do you good to run it off of a gas can full of fresh gas and see how it behaves.

You don't need a new carb. At worst, this one is gooped up inside....even paying to have it gone over is much cheaper than a new one. Seems like a lot of people that don't understand carbs just say "I need a new carb". Drives me up the wall...if it's not warped/cracked/seized, I'd keep the carb you've got.

The only carbs that deserve to be summarily file-13'ed are Holleys that have been monkeyed with and 99.9% of all QuadraJunks. :lol

Edited: Now that I got that out of the way...I'd guess the floats are set too low. Only fuel related thing I can think of off the top of my head :lol

[nymustang]

Hmmm, interesting. I need to pay attention to how long it takes to drain. Just started it today, I'll take a look at it tomorrow. The car does tend to sit for LONG periods so I guess I should figure out just how long it does take, usually seems like a day or so and the clear fuel filter is empty. The pump functions fine and pushes gas up into the carb so unless there is a leak somewhere i don't know where the gas is going. There are no leaks by the way, solid clean connections with new hoses and clamps. No drips or smell of fuel.

On the old gas note... yeah its bad. I know. I had to pull the carb apart maybe 3 months ago and clean it out because it was getting gummed up. I need to do this again for sure I think but my needing a new carb is sort of unrelated. Its a 750 CFM sitting on a 302. Way too much carb and I've discussed with others on this board the fact that the 750 Edelbrock is not really a great piece of machinery anyway. I'd like to live with it as long as I can so maybe another good cleaning and some fresh gas will do me good for now. To help me along, I just ordered a new tank and sending unit. The fuel line is only about 2 years old so I'm not worried about that. Lets hope NPD is quick.

[AzPete]

My '66 with a 289/edlebrock 600/elec. fuel pump drains back within a day. If I pump the pedal without letting the furl pump fill the bowls, I get a hard start. If I let the elec. pump run a second before starting, it starts and runs great.

I am told by several that this is normal......I still do not agree with it being normal but have no idea as to why at this point.

Car has no other real issues.

[nymustang]

So you have a similar problem but an electric pump. I'm running mechanical. I was thinking an electric might help me out a little.

[AzPete]

The only way it helps is I can pump fuel without the engine having to turn over.

[Kats66Pny]

If I let the elec. pump run a second before starting, it starts and runs great.

Same here. If I flip the pump on, let it run a few seconds, starts up no problems.

[silverblueBP]

I have a mechanical pump in my 289 and when the engine is not BROKEN, I don't have a drain back issue.

[AzPete]

You don't really want us to start talking about our engines that run do you....?

[silverblueBP]

No cause it might derail this thread 

[AzPete]

At least you cannot derail much now....sorry, the devil made me say that......

[silverblueBP]

 :nk  that hurt Pete.

[AzPete]

I said sorry.....

[sigtauenus]

I just pulled the carb to change out some parts, and it was drained in the process.  When I put it back on, I spun the engine over a couple times, maybe 10-20 seconds, then pumped the pedal and it fired right up. 

Even if your fuel is draining back down, it shouldn't take that long to refill the line, and certainly not so much that it drains the battery. 

Could this be a battery related issue that your low power and not spinning the engine over as fast as it should thus not pumping as much as normal?

[Opentracker]

Could be a weak fuel pump. Those things pump a lot of fuel with the line unhooked from the carb. When I put a new carb. on the car, it only takes a few spins to fill the bowl and it fires right up.

Take the line of the carb. and put it in a clear bottle so you can see what goes on and spin the motor. It should pump in large squirts with every revolution of the cam. If you want, put a length of fuel line on at the carb. and put the bottle on the ground.

[buening]

The mechanical pump does have an anti-drainback valve but it will not hold that pressure more than a day. You will notice that the fuel will stay in the lines after sitting a few hours, which proves that the valve is there and working.  However after a day or two it has slowly leaked the fuel back down. Regardless, you'll have fuel evaporation in the fuel bowls (through the carb vents), and the pump has to replace this fuel in order to have a quick start. 

[blue65coupe]

Take the line of the carb. and put it in a clear bottle so you can see what goes on and spin the motor. It should pump in large squirts with every revolution of the cam. If you want, put a length of fuel line on at the carb. and put the bottle on the ground.

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