gas disappearing overnight from fuel bowl

289 - 351 cid Small Block Performance
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CAComet1965
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Joined: Mon Feb 13, 2017 2:36 am

gas disappearing overnight from fuel bowl

Post by CAComet1965 »

Ok.
My comet runs amazing once I get it started (all though its starting to make a washing machine noise)
Here's what I've done.
1. dropped my tank...not rusty nor dirty
2. replaced brass float and the nylon intake sleeve
3. New rubber line from gas tank to fuel line.
4. new rubber line from fuel line to pump
5. new fuel pump
6. rebuilt my carb.

When I park my car overnight, sometimes it's a struggle to get it started. I usually resort to starting fluid.
I've pulled the fuel line to the carb, turned it over, and it's pouring gas (into a glass bowl). I've taken the top of the carb off to confirm my bowl is empty.

Here's something to add to the mix. My driveway is on a steep angle. If I park with the gas tank higher, it is easy to start. If I park with the front higher, it's a $@^-#! to start.

It can't be vaporlock, it is winter in SO Cal (65 degrees).

Could it be possible that the gas from the bowl is leaking back into the fuel line..but isn't the fuel line primed?
Did I mess up on the carb rebuilt? I don't have another 2v laying around to test this theory.
Are my floats not adjusted correctly....
My chevy buddy thinks it might be my bowls leaking into the cylinder heads....maybe explaining the washing machine sound? (I've messed up my heads)
Or is my mind playing tricks on me.;

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poboyjo65
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Re: gas disappearing overnight from fuel bowl

Post by poboyjo65 »

Maybe your needle seat letting it get back thru but it may be leaking out the power valve on the bottom of the bowl.
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Johno

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Groover
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Re: gas disappearing overnight from fuel bowl

Post by Groover »

John, do you mean the needle seat at the top where the needle drops in? or do you mean where that brass cylinder screws into the bottom of the bowl? The needle seat is closer to the top of the bowl, isn't it, so it could leak some but wouldn't go bone dry. Power valve sounds more likely to me. Don't rule out heat soak/evaporation just because it's winter. Do you have any carb spacer? If the engine is hot when you park it, some may go via evap.

Have you let it sit overnight, then gone out in the morning and opened the bowl to take a look and see how much fuel is left in there? When I drive mine daily it usually starts with one pump of the pedal, but if it's sat for a few weeks, it takes five pumps and a little cranking. I've never added starting fluid.

And what's the washing machine sound? Your Comet getting Agitated ;)
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1964 Comet Caliente Convertible
30,000 miles on our rebuild

All Comets start out as dreams...

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poboyjo65
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Re: gas disappearing overnight from fuel bowl

Post by poboyjo65 »

Groover I was just thinking if on a lean & dirt on seat might get a siphon effect going & draw it back out. :roll: heat evap is probably more likely. where in the heck is that click clack gang? :lol:
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Johno

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Groover
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Re: gas disappearing overnight from fuel bowl

Post by Groover »

poboyjo65 wrote:Groover I was just thinking if on a lean & dirt on seat might get a siphon effect going & draw it back out. :roll: heat evap is probably more likely. where in the heck is that click clack gang? :lol:
This morning it looks like it's you and me. You wanna be click or clack?
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1964 Comet Caliente Convertible
30,000 miles on our rebuild

All Comets start out as dreams...

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poboyjo65
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Re: gas disappearing overnight from fuel bowl

Post by poboyjo65 »

Groove in my day it was Wally ,goober & gomer! :lol:

judy judy judy. aaaalright you guys lets go you guys come on you guys beat it you guys. :roll:
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Johno

CAComet1965
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Re: gas disappearing overnight from fuel bowl

Post by CAComet1965 »

You guys made my morning.
Yes, I've let it sit overnight and opened up the carb to find the bowl empty.
When I park on my sloped driveway with the gas tank higher, it tends to start up quicker.
I was thinking it's something with my carb needle.

How long does fuel vaporize from the heat of my motor? I've parked it and started it a couple of hours later with no problems. Starts without pumping gas on the first try.

Are the same gnomes that steal left socks poaching my gas?

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poboyjo65
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Re: gas disappearing overnight from fuel bowl

Post by poboyjo65 »

You might try laying a piece of paper towel or toilet paper under the power valve over night to rule it out. I dont know if cameras could catch them little gnomes. :x
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Groover
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Re: gas disappearing overnight from fuel bowl

Post by Groover »

From what I recollect of the innards of the 2100 -- that is what we're talking about, right? Otherwise forget nearly everything I've said ;)

Clack, you check me...

1. The fuel inlet needle is nearly at the top of the bowl.
2. The fuel inlet needle seat screws into a raised area that's above the bottom of the bowl.
3. The only holes on the bottom of the bowl are the power valve and the jets.

If you had a leak at the inlet needle or the needle seat, then the bowl would flood as there wouldn't be enough back pressure to stop the fuel from coming in. In that case I think it spills over into the main fuel well. It would also run rich and you'd probably have a hard time starting after running and you'd probably smell gas and have gas coming out vent tube on the top of the carb. Even if fuel could leak back down the fuel line (or was sucked back down as temp dropped and vacuum in the line occurred), the point of entry is higher than the bottom of the bowl so it wouldn't be bone dry.

If you look in the bowl the next morning and the bowl is near bone dry, then it would likely be the power valve leaking it down into the manifold via the vacuum port that normally pulls the power valve closed during regular operation. This would also create a run rich condition and horrible gas mileage. I don't know if you'd see this leak on a piece of paper underneath the carb unless the gasket to the power valve cover was also bad or soaked with gas.

If you check and your low in the bowl, but not bone dry, then it may be evaporation (or a combination of the two). If the manifold is 200 degrees and the carb spacer is not effective (or you don't have one) then the carb is 200 degrees. I think today's gasoline boils (or evaporates) at something like 180 degrees. Engine temp rises after you shut off the car so that's prime time for evaporating gas from the bowl (out the vent or into the main well and down into the intake). Ask me how I know :oops: I have this problem even with an aluminum carb spacer.

I'm betting on power valve and that's a cheap fix (although I don't think you can do it without taking the carb off).

Let us know.
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1964 Comet Caliente Convertible
30,000 miles on our rebuild

All Comets start out as dreams...

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poboyjo65
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Re: gas disappearing overnight from fuel bowl

Post by poboyjo65 »

Well click that all sounds logical , but remember the old coffee percolators? had the clear deal way up top? Throw that in your hat! shake it around , & see what falls out :lol: :lol: :wink: & your momma's pressure cooker, had all those knobs for a reason, plus it had a safety valve. needle /seat could be acting as the safety valve, other wise it may spew all over the motor out the bowl vent, but I'm just guessing here. but I suspect the bubbles would let the float bounce letting off steam & gas. That's whats up in my hat ,,,take it away click!!!! :lol: :lol:
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CAComet1965
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Re: gas disappearing overnight from fuel bowl

Post by CAComet1965 »

the carb is a holley 2v if that makes a difference

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poboyjo65
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Re: gas disappearing overnight from fuel bowl

Post by poboyjo65 »

we might have to get wally on that holley! :lol: :lol:
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Jims65cyclone
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Re: gas disappearing overnight from fuel bowl

Post by Jims65cyclone »

Dear Click and Clack,
Since you're rattling ideas around in your hats, try this. The gas cap isn't venting, creating a suction. When the car is parked with the tank downhill, the gas is sucked back into the tank until the bowl empties and breaks the vacuum. When the car is parked with he tank uphill, it does the same thing, but when the vacuum is broken, it refills the bowl by gravity. It would probably suck dry if parked on level ground, too, if left that way long enough, like overnight. How about it, CA? Have you ever parked it on level ground long enough to have the bowl run dry? Just a wild guess, but, then again, I don't have a radio show. :roll:
Jim
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poboyjo65
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Re: gas disappearing overnight from fuel bowl

Post by poboyjo65 »

you do now! you're hired!! :D we need a fill in guy . I think Pops internet is out from the storms today. he sends all his left over storms to me & it got pretty ruff here.then there are vacations, holidays ect, bottom line we need ya ''clunk''! :lol:
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popscomet
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Re: gas disappearing overnight from fuel bowl

Post by popscomet »

DO YOU HAVE THE CARB bolted right on top of the intake...{other then a paper thin gasket }
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