Fuel leak question

[zimmy]

I have been fighting a problem for a while and need someone's help. I have 48 IDAs on a big block with the 10 deg canted intake. Whenever I stop the car after a drive, the heat seems to percolate the fuel and I get dripping out of the accelerator pump jet. It collects in the throat and eventually leaks out of the throttle shaft onto the manifold.

I have a return line on the fuel so it should be immediately dropping pressure when the car is turned off and I have the phenolic gaskets under the carbs.

Any suggestions? Has anyone else seen this problem and can you explain it to me and the solution???

Very frustrated!


Thanks.

[OCCOBRA]

I also have a BBFE and IDA's and had heat also percolating the sh$t out of them. problem... too much heat under the hood flowing through hood opening heating the bodies of the carbs. The heat is not coming up through intake its the air passing by the carb bodies. Carbs were so hot I could not hold my hand on them. I wrapped my headers, and added angled shroud to back side of rad to through heat down. Really helped out . I have a straight up (not canted) intake with a large opening in the hood, no scoope. So I really had air flow up and alongside carbs. I also plan on shrouding the top of the Rad because alot of air is still flowing up past carbs but fan angled down and wrapping headers really helped

[Eljaro]

Zimmy,

I have been fighting a problem for a while and need someone's help. I have 48 IDAs on a big block with the 10 deg canted intake. Whenever I stop the car after a drive, the heat seems to percolate the fuel and I get dripping out of the accelerator pump jet. It collects in the throat and eventually leaks out of the throttle shaft onto the manifold.

I have a return line on the fuel so it should be immediately dropping pressure when the car is turned off and I have the phenolic gaskets under the carbs.

I have exactly the same problem. The biggest problem is that the fuel also drips into the engine and will end up wearing your rings prematurely.
The fact is that the carbs are absolutely cool when I arrive at my garage, even after hard driving, but after about 10 minutes they are hot as hell and and I can hear a boiling noise and gasoline dripping out of the pump jets.
The phenolic spacers help, the return line also, the smallest pump bypass did not, but the problem seems to be the heat emanating from the engine after shutdown and rising around the carbs which heats them up. Also keeping the hood open does not help.
I did build myself a heatshield for one carb in order to see if it would help, but it did not. I am seriously thinking of installing a fan to get the heat out of the engine with a timing device so it will come on when I shut of the engine off and stay on for about 15 minutes. Where to install the fan is what I am thinking about now.
I read somewhere Rick Lake suggesting to install two fans, one behind each side vent. That could be an elegant solution and would also help during hot days and slow trafic to keep things cool.
I am thinking of some type of 5 inch computer fan with low consumption, because if necessary it could stay on longer without draining the battery.

This is right now my only problem with the webers.

[zimmy]

Eljaro:

I am at least glad to know that I am not alone. I know it isn't heat from running. When I saw this problem again this week after the engine was back in the car (long story) and I went for the first drive. It was 45 deg F outside and the trip was fairly short. I also think that it is heat sink after it is parked a few minutes. I'll keep looking for a solution and will let you know if I find anything.

Happy Holidays.

[cobrakiwi]

if you run an electric fuel pump only turn pump off before you turn your car off, hit the gas pedal a few times to empty some of the fuel out of the webbers.
This used to work for me on a 289 with IDA's I had a few years back.

[Eljaro]

The problem is the fuel trapped inside the pump conducts in the carb body. The carb heats up and the fuel inside the pump conduct has probably some air trapped along the way, which expands with the heat and pushes the gasoline out the pump jet. The pump draws the gasoline from the bottom of the bowl, so a lower bowl level should not be of much help.
I think only shielding or some type of evacuation of the hot air should help.
I am going to try a pair of Muffin type fans mounted behind each side vent and improve the heat-shields I have already made.

[priobe]

Any news to resolve this problem?

[Rick Parker]

I think that if you set the float levels with the carbs setting FLAT on a workbench and then install them on the engine (angle mount) that the fuel will be level but higher inside the float chamber towards the centerline of the engine because the float fulcrum is on the low side of the carb when it's mounted on the manifold. I don't have the answer but believe a lower float setting is the solution. I think also the fuel would drip from the auxiliary venturis before the accelerator pump jets.

[priobe]

Now that I think of it.. I never had this problem before until I had the carbs off the motor. At that time I readjust the floats. I usually adjust the floats on the motor and never had that problem.

Rick, I do believe you might be right

[Rick Parker]

Acknowleging the above, it is also possible that by lowering the fuel level to eliminate the drip issue that the emulsion tube selection may be effected a minor amount. As John Passini the author of 2 great Weber Tuning Guides from the 60's once said about jetting choices... "Suck it and see".

Good luck

[priobe]

has anyone any update to resolve this problem?

[priobe]

Did those of you experiencing this problem alway have the problem of fuel pouring from the pump jets?

What changed?

Please respond.

[priobe]

bump......

[carmine]

Yes always dripped after shut down.
Only way i could see it not dripping is if you are running to cold of a thermostat eg) 160 deg.
Maybe thats what changed. Where you running a 160 and then changed to a 180 or 190.
Webers love heat.

[Rick Parker]

The carbs are ment to sit level! If they are on an incline with the pump squirter (now lower) towards the inside of the engine the fuel level will be further up in the pump well and may be leaking as you describe. Lower the fuel level.

[priobe]

I dont recall my pump jets ever leaking. I have tried shutting down my pump to lower the level a block before shutdown. It still leaks

The only thing in my situation that changed was new pump jets( which I replaced back to the old) and float level (which I lowered before shutdown.

The carb bodies themself are cool to the touch.

Zimmy,

Has your system always leaked?

Eljaro,

Has your system always leaked?

I dont recall other complaining about the leaking from the pump jets.

Rick,
I am not saying you are not correct but it seems something changed to cause the pump jets to start leaking. Or I never noticed it.

One thing, if you block the by pass all hell breaks loose through the pump jets.

Maybe its the fuel?

Just when I think I am moving forwad with these carbs I go 1 step back.

[carmine]

A zero bypass valve will most defanetly biuld up fuel pressure in the pump chamber caused buy heating up of the carb body and expanding the fuel which has no place to escape except out the pump jets.

The larger the bypass valve # the more of the pressure biuld up will divert back to the main float chamber, Thus allowing less fuel out the pump jets during pressure build up from shut down heat sink of carb body.

Yes your carb body will be cool to the touch after shut down.
Check how hot they are 10 minutes later.

The pump Jets are not affected by the angle the carbs are on because they are fed by an inlet located at the bottom of the main float chamber.

[priobe]

Originally Posted by carmine

The pump Jets are not affected by the angle the carbs are on because they are fed by an inlet located at the bottom of the main float chamber.

Is there anyone that has a 10 degree intake that does not leak.

"This thing is driving me nuts!!! I dont ever remember mine leaking"

[carmine]

I think they always leaked and you never noticed it.
More so now that you have a #0 bypass valve.

[Eljaro]

My Webers have always leaked and are one of my main concerns right now.
The pump bypass does not help, I tried that out with the smallest one possible (0.35) and only got a bog when accelerating. The phenolic spacers helped some but did not totally do away with the problem.
When I stop the car the Webers are cool. After a while they get really hot from the engine heat. They get so hot that the fuel trapped in the conduit between the pump plunger and the pump jet starts boiling (you can hear it !) and drips out of the pump jet. And it can be quite an amount.
The float level has no effect on this because the pump circuit gets the gasoline from the bottom of the bowl as has been said here, and if you lower it too much you can get fuel starvation when taking fast and tight turns. This problem has nothing to do with the fuel level and fuel supply by means of a bypass, lowering fuel pressure or letting the fuel bowls empty some before shutdown.
The only way to get around this problem is to get the hot air out of the upper engine bay.
Maybe a flexible duct drawing air between the Webers and with an exhaust fan infront of the engine or behind it or a 12 Volt computer fan behind each side vent in the engine compartment and have them come on when you shut down the engine. This way you remove the hot air that is trapped under the hood.
The aluminum Webers heat up fast with the hot air trapped under the hood and slowly exiting through the scoop.
This can be done elegantly with a relay and a timing circuit so the fans come on automatically and shut off after 10 minutes.
What I do now and what really helps is to open the hood when I stop and the heat gets out fast and does not soak up the Webers. No dripping this way.