Carburetor float bowl emptying out overnight

[Redmond49]

My 46 sat for about a year and when I went to restart it, it started right up with just a bit of starter fluid. Then it sat a few weeks and when I came back to start it, it would not start and no amount of cranking or starter fluid would work. I replaced the fuel pump, but that didn't help. Then I somehow decided to open the carb, where I noted the float bowl was dry. So I filled it up and the car started right up and I ran it for 15 minutes with no problem. That was about a month ago; last night I got the car all back together (new brakes) and the car would not start with starter fluid, so I again popped the top on the carb, filled the bowl with gas, and started her up and went for a short test drive on my new brakes.

 

Today, I went to start it expecting it to start easily but it did not. The carb bowl was dry, and filling it did not help. The gasket between the top and bottom of the carb is thin brittle paper, I'm wondering if the opening and closing has disturbed it enough to cause this problem. Any thoughts? 

[pflaming]

I constantly check the top bolts on my carb. They tend to loosen. I would replace the gasket, but make certain the top of the bowl and the bottom of the lid are clean and square. JMHO 

Edited October 18, 2018 by pflaming

[Andydodge]

I'd be getting a carby kit and replacing all the gaskets, the accelerator pump plunger if its included and the needle and seat.........at least then you should in theory have a carby that shouldn't leak or loose fuel...........at least thats how I'd start the problem solving........also try and get new spring washers for the bolts on the carby top .........andyd 

[Plymouthy Adams]

as you did not open the top after the short drive you do not know for certain if the fuel bowl was truly filling up.....your constant priming the bowl would allow it to run long enough for a fuel pump that my have a small pin hole to suck a bit of air along with a little fuel when actually running.  This small hole could truly prevent it from sucking the heavy fuel from the tank and through the short upturn to the pump itself.  The little fuel you was getting may have been enough to sustain a run that did not include some heavy acceleration runs from stop to a continuous high speed run.  As you are always having to prime, I would investigate the very delivery of fuel to the carb from the pump.  Start with a fuel pump test to ensure there is gas being siphoned from the tank and that x strokes of the pump equals x amount of fuel.  The manual can assist you here, approx. 15 stokes of the pump should equal between 5 to 6 ounces of fuel.  If  you wish to check with pressure, should be 4.5 approx. lbs and when you stop pumping should slowly lose pressure.  Immediate loss of pressure says you have a leak either in the pump valve or diaphragm.   Modern gas evaporates much quicker these days.  Another test is to fill the bowl with cover off and visually check for seepage/leaks...if none immediately showing, fashion and place a flat cover over the bowl and let stand for a few hours and see if the fuel is there when you check it after that time.  I would suspect more of a low inadequate flow into the carb over the fast speedy evaporation or seepage.  

Edited October 18, 2018 by Plymouthy Adams

[pflaming]

1 hour ago, Andydodge said:

also try and get new spring washers for the bolts on the carby top .........andyd 

 

Andy, I'm going to get new spring washers tomorrow. The bolts should stay tight. TKS. Tims explanation was helpful also. TKS.

[Andydodge]

Paul............ yep Tims right re the fuel pump as well..........in a general sense both the fuel pumps state of health and the carbys various issues should probably be looked at as one or both affect each other and without playing with both you can sometimes end up chasing your tail...........lol.............believe me, we all have enjoyed this experience over the years...lol.......the only hiccup I've sometimes found with trying to get new spring washers for these small machine screws or bolts is that sometimes the old spring washers are a tight, difficult to remove fit around the threads and have to be cut off with a pair of sharp snips, also the "new" washers may be hard to get in the exact size , at least here in Oz due to the mongrel "metric" size that supposedly is the same size.............ah, the joys of old cars..........lol............andyd.  

[Dartgame]

Might be a sticky float valve...fuel pump is more likely a pin hole leak.. Be sure to check your oil. You may find its got a bunch of gas in it.

[Redmond49]

Thanks for the pointers!

[rhelm1953]

The only way the fuel can leak out of the bowl overnight would be if the bowl had a crack or a pinhole.  When running the fuel is sucked up and out by low pressure (vacuum) in the venturi or by the accelerator pump pushing it out.  The old carburetors do not have a sealed bowl so fuel can evaporate but that is not likely to happen overnight unless the engine is really hot and boils the fuel.  If you refilled the bowl and the car did not start then either your problem is not fuel related or the carb is dirty and fuel passages are plugged.  It is possible when removing the carb top you bent the float adjustment so the float is not letting the bowl fill or as Plymouthy said you should check the fuel pump delivery, one other possibility is the float needle is stuck or clogged with dirt.  I would verify there is good spark and check the engine vacuum when cranking, if that checks rebuild the carburetor.  The beauty of these old cars is the simplicity that makes troubleshooting fairly easy.

[Fernando Mendes]

On 10/18/2018 at 10:59 AM, Redmond49 said:

Thanks for the pointers!

Review your fuel pump.

[Redmond49]

I took the carburetor off. There was a quarter inch deep puddle of gasoline sitting in the bottom of the intake manifold (solid bottom, apparently not the original manifold).

[rhelm1953]

With the carburetor off the car have you tried filling the bowl with the carb sitting on the bench just to see what happens?

[Andydodge]

Have you got a carby kit?......thats what I'd be doing, throw a kit in it with new gaskets, needle & seat & accelerator pump and new spring washers & it in theory at least should be good to go.........lol..........in theory anyway.......lol.........also check the various linkages and their pivots, see whether there is too much "slop" and if so see what can be done to fix that, maybe an extra washer in the pivot to reduce the sideways movement.........other things to look at while your there include the fuel pump for any rubbish in the pump valves, install a filter if none there, check & clean the air filter etc.......all these things can affect how it runs, while your fiddling, check the lot................lol..............andyd