Stopping fuel drowning my Webers

[Eljaro]

I have tried all sort of things to keep the heat off my 48IDA. The carbs usually stay cool during driving, but rapidly absorb heat when the engine is stopped. After a while the fuel inside the acceleration pump circuit start boiling and pours fuel into the throats, making starting difficult and washing my cylinders off oil.

The phenolic spacers did help some, but still are not the solution, besides that the air horns are too close to the bonnet and I have experienced the horns being knocked off its position by the rocking engine.
So I have decided to go a different route. Since I have a mechanical fuel pump and want to stay that way, I have purchased a solenoid valve, 12 Volt, normally open, with Viton seals, which I am going to plumb between the fuel pump and the pressure regulator.
One simple push switch in the dash and a relay behind it will do the trick.
Before turning off the engine, maybe 5 seconds before (I have to test the time it takes for the bowls to become empty), I push the switch which activates a relay, wired to hold itself activated until the ignition is turned off.
So the fuel supply is interrupted for a while, the fuel level inside the bowl and the acceleration pump circuit will sink and when the engine is turned off fuel will be low enough to prevent it from boiling over into the throats when the carbs get hot with engine heat.
I will take the phenolic spacers off and hope to get done with the fuel issue.

[Rick Parker]

It is entirely possible that when you release the switch that the springs that create the pressure within the pump (Mechanical Pump) will force some volume of fuel into the fuel lines, how much remains to be seen and taken into consideration.

[digginfool]

As a routine, when I get about a half-mile from my house, I turn off the fuel pump. By the time I get in the garage, the car is sputtering as it uses up the last bit of fuel in my carbs. Basically the same thing you are trying to accomplish, just without the solenoid.

[gsharapa]

Couple things you might want to consider; Put a return line back to the tank off the regulator as it will keep the cooler fuel coming up vs just letting the fuel dead head and heat up. The other is what kind of fuel are you using ie; in the U.S. there are a lot of stations that have methanol blend and methanol blend fuels boil at a much lower rate. I had the problem at a Cobra meet in Austin, Texas (late March) as it was lower 90s and the fuel was boiling in my carb. I ended up putting 5 gallons of 107 in it and that fixed it but clearly staying away from methanol.....

[Gaz64]

Two of my cars have Webers and both have electric pumps and return regulators.
I never have hot fuel handling issues.

I would be removing the mechanical pump and your dead head regulator, installing a return line and running a bypass fuel system similar to EFI.

Fuel delivery is much smoother, the carbs are happier receiving the cooler fuel flowing without pulsations.

Wondering on why you wish to keep the mechanical pump?

[vector1]

fuel probably starts collecting heat off the mechanical fuel pump.... isolated electric as above could be better in that respect.

[lemans24]

i turn my fuel pump off and run the gas out till the engine starts to stumble. that does help some. my take on it is the fuel in the bowls is boiling and the pressure from the boiling gas is forcing it out the top of the carbs. i put on phenolic adapters to try to isolate the bottom of the carbs from the manifold.
alot of people are having th same problem. must be the fuel. i'm going to run only non ethanol gas and maybe try some seafoam.

[Eljaro]

After having driven the car hard and stopping, the Webers are real cool at the touch.
So it not a problem of the fuel pump or anything else heating up the carburetors. They stay cool just by the air which flow through them.
They only start warming up when I stop the car because of the engine heat accumulating under the bonnet. Stopping the engine still releases a lot of heat inside the engine compartment
Most of the time I open the bonnet and it helps a lot. The phenolic spacers are not of any help in this case. The hot air transmits teh heat to the aluminum,( which conducts heat very easy and fast) of the carburetor body and starts to cook the gasoline inside, which then boils over.
The only way around it is to reduce the fuel level inside the carbs before stopping the engine. Fuel will still boil, but it stay inside the bowl.
This can be done only by turning the electric fuel pump off shortly before stopping or by closing off the fuel supply to or from the mechanical fuel pump.
I removed the intake manifold yesterday in order to get rid of an oil leak at the rear rail seal, and saw all intake valves sitting in a puddle of a mix of gasoline and oil. That is no good, so I am taking this route.Since I want to stick to the mechanical pump, a valve to close the fuel supply is the only way to do it.
I am installing the valve and will report my experiences with this modification.

[digginfool]

To clarify, that is the issue with the Webers. The fuel doesn't boil while the engine is running. It boils from heat-soak after the engine is turned off. In addition to turning off the fuel pump on my way home, I also open the bonnet (hood to us Yanks) to let the heat out of the engine compartment.

[priobe]

Every year around this time, this topic comes up. I believe what we are experience is the summer blend of the fuel.

What I have done is readjusted my floats to 24mm x 5.5 mm and so far that cleared up my problem. I dont want to speak too soon but hopefully this does it. I am finding that I may need to change the e-tube for compensation.

I use to run my floats slightly higher than recommended because of the canted intake but I dont think it make that much of a difference.

I too have used higher octane or fuels without methanol but it is difficult to find.

You may want to check you float levels and see if this helps.

If it does continue, my next solution is like what one member said sea foam.

I use an electric pump and sometimes forget to turn the pump off before shutdown. I will not start the car just to run the bowls dry. It actually holds alot of fuel

Please those trying different methods post your results. I am curious to see the out come.

I am runn the spaces too.

[Snakebit]

I had a problem of fuel leaking out the throttle shafts on to the intake manifold. I would run the car and the next day smell gas fumes in the garage. When I opened the hood, there was a puddle of gas on the intake manifold. I thought it was a stuck needle valve, so I removed the covers and cleaned them. The problem re-occured so when I loosened one of the fuel line block conector bolts, gas sprayed out. But the car was not running, so where was the pressure comming from? I opened the gas cap and there was a hiss of air escaping. I opened the fuel line again and no more pressure. So pressure was building up in the gas tank, going back through the return line, and forcing gas out the needle valves.

Vented gas caps only vent in, not out. I drilled a 1/16 hole in the vent of the gas cap and my problem is solved.

[Rick Parker]

Remember the 70's Chevys that had the fuel filler behind the license plate? Every once in a while you would see one pull away from a stop sign and half a gallon of 60 cent gas would pour out the back, those were the days.

If the vented caps get plugged it could cause your fuel tank to collapse from the vacuum created by a mechanical pump, that used to happen occasionally.

[Jac Mac]

Put the Webers in a plenum...

[Caprimaniac]

Eljaro; Me too has some belief in a return line.

The problem have almost vanished since this system was installed.

I am also lucky since I have an electric water pump which I keep running some 5 minutes after shutdown. Helps cooling down faster.

RS

[*13*]

I thought I was the only one... I just re checked & adjusted my float levels last night. I set them closer to 6.0mm. We'll see what the result is.

[priobe]

Hello all,

I live in Miami FL where temp reach 95 F this particular day. I use to run into the very same problem and it use to be very bad. I would have to hold the throttle plates open to start the car after a drive and letting it cool for about an hour.

What I did was adjust the floats using the weber adjustment too that I made to 5.5 mmfloat height and 24.2 mm tang height.

I have driven the car and each time car starts right up. I would even keep the fuel pump going to lower fuel level, and I have no need to do this anymore.

I would check your floats adjust them to default setting and if the car runs bad use a correct emulsion tube to tune your driving experience.

So far its working for me.

I am also using the spacers

[*13*]

I purchased my float adjustment tool from Gene Berg. It's a quality part, if anyone is wondering where to get one.