On my 1970 144s with twin Strombergs on a B 20B engine, the front carb is pouring out fuel from what the Volvo Service Manual calls the "Drilling for air supply under diaphragm".

It flows out the 90-degree curved pipe through a hose to the Hot Start Valve at the rear of the air cleaner box, and from there pumps fuel through that valve and back into the air box, filling it.

What's going on here?

It depends on whether the center bottom plug is plastic or brass. The brass one SHOULD unscrew.
You may have to use force.
I'd guess the O-ring is stuck to the bottom cover.
Maybe a bit of carb cleaner around the bottom plug will loosen it.
In any case you HAVE to get the bottom cover off.
You are experienced enough that this should not be too big a deal.
Missed you at Carlisle in May. Daughter now lives in Mechanicsburg so we stayed with her.
Don't give up!
Fresh out of Tulsa hospital after a painful lung biopsy. I'm at the end of a 50 ft plastic tube...
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George Downs Bartlesville, Oklahoma

I'm having the same problem with my Stromberg carbs. In my case, it is due to fine rust from the tank getting into the float needle valve and holding it open, causing flooding. The hot start valve was removed (and the hole where it was plugged)from my air cleaner box by a previous owner, and the float bowl vent holes on the front of the carbs no longer have the tubes connected that would have gone to the hot start valve, so now the fuel just overflows directly into the air box until the engine stalls. Fortunately the air box hasn't let the fuel drop onto the exhaust manifold to cause a fire. From what I hear, the Stromberg float needle valves are very prone to sticking open, even from the smallest particles of rust or dirt in your fuel, or from too much fuel pressure. I had just installed a new fuel pump, so I suspected the pressure might be too high, and I knew I was getting some rust from my fuel tank, so I tried the following: I removed my fuel tank and cleaned it thoroughly, installed a fine inline fuel filter, a fuel pressure regulator and gauge so I could cut the pressure down to around 1.5 psi (the new pump was putting out close to 5 psi), but I'm still having the problem. What I am finding when I take the carbs apart is extremely fine rust (fine enough to pass through the fuel filter)in the form of sludge in the bottom of my flat bowls. By the way, when I remove the float bowls, I do remove the big center plug from the bottom so that when I whack them with a wood block they can break loose more easily. I just ordered some "grose-jets"---a type of needle valve I'm told is less sensitive to pressure and debris, and I'm hoping they will allow me to drive out the remaining small amount of rust in my fuel tank. If not, then I will likely need a new fuel tank. Just a word of caution regarding the hot start valves---if the external hose leading to the charcoal cannister leaks or has been removed, it can drop gasolne directly on top of your hot exhaust manifold and potentially start a fire.

Did it just do this out of the blue, or have you made any changes? Did you remove the charcoal canister and/or cap the float bowl vent? That'll cause fuel to come spewing out everywhere.

If you haven't done anything, then check the float.

Happened suddenly. This is a car that sits in the yard because it is a parts car or restoration project with about 133K Miles and was parked in 1991.

I run the engine occasionally and this issue just showed up. I put on a spare carb which came with my purchase of the car, ans this was enough to let me drive the car closer to my garage and take the leaking carb to my workbench.

But I can't get the cover off the fuel bowl.

DO NOT PRY. The gasket surface will be destroyed in an instant.

A guy who taught me some of the greatest stuff I ever learned about cars, taught me this important lesson: Don't bang harder; get a bigger hammer.

This seems like crazy advice but it turns out that you will do more good with less damage, by hitting more gently with a bigger hammer. Banging away with a small hammer will nick the thing again and again, slowly deforming it; one heavy thud with a 3-6 lb sledgehammer will get it done without damage.

Find a way to get the carb held firm in a vice (wood is your friend) and put a 2x4 against the float bowl, and give it one good controlled knock thru the 2x4 onto the float bowl.

Not a fast out-of-control swing of your little peening hammer, no sir -- use a huge hammer (way bigger than you think you need) and swing it slowly. It's counterintuitive, but the big hammer will require a much smaller swing and thus will be both more effective and less destructive. My first choice here would be about a five pound sledge.

I have not done this before, but you can try as an idea to dunk the lower part of the carb into boiling water. Only the cover, nothing more. The idea being that the cover will expand but not the body, breaking the seal between the halves.

The heaver hammer results in more force transferred with a slower impact in less blows, assuming the body is gripped in a vice.

Agree with the others, especially after reading it's been sitting for over 20 years, probably gunked up. Try carb cleaner inside, or something stronger. Just know that you will destroy the diaphragm as it cannot handle carb cleaner.

Most likely the float sprung a leak and is filling up with fuel. It is just a plastic bubble, and you can make the hole larger to get the fuel out and then reseal it. Or else the float valve is sticking from deposits/dirt/gunk, which again is easy to clean once you have it open.

It is very easy to remove the fuel chamber cover, but you probably will want to get a new gasket as a minimum. Don't remove the temperature compensator on the side, or anything you don't have to. The rubber seals will be brittle and you will create a major leak if you remove it and don't have replacements.

How does the feul valve cover come off? I removed all six bolts but nodice.

I can't unscrew that large bolt in the center, so...?

No, the centre bolt stays in as it does not hold anything together. It is only the screws around the bowl that needs to come out (from memory, it's been a few years). Very likely the cover is stuck on from gunk that seeped into the gasket, just give it a few gentle taps. Don't have to be too gentle.

That's what I thought, but I've hammered on the cover all that I dare to and it only twists just a little -- not even enough to pry with a small screwdriver.

If it turns out you need some parts for those Strombergs, send me an email.
I have a box of Stromberg parts that I have no use for and can send you some for the cost of shipping.
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"Differences of opinions should be tolerated, but not if they're too different' - Sharon Craig

Sounds like the float valve is sticking open or otherwise not sealing.

Don't know stromberg float setup, so I can't help beyond that, but if you've got a manual, I'm sure you'll figure it out...

find and clean said valve, and check operation. And make sure the float didn't get a leak and fill up with gas, turning it into a sinker...

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-Matt I ♥ my ♂