Carburetor runs fuel after engine turned off

[MonsterMovie]

Hi There. 1972 Type 3 fastback with dual PDSIT 32 carbs. Rebuilt carbs, fixing a concave pump cover in the process.

Now, both carbs are leaking fuel after the engine is stopped. I discovered the leak is coming from the throttle plate linkage - which is a bit old and loose. Turns out when I run the engine for a while (one minute) and stop the car, the two injectors (accelerator pump and power fuel system) at the top of the carb throat continue to drip/flow fuel (left-side pic below). This fuel gathers on top of the throttle plate and then leaks out around the loose linkage.

So, now I know what's happening but I don't know why it's happening.

I was told in a different post that my fuel pump may be a higher PSI than recommended (right side pic below). Would that be an issue-releasing pressure from the bowl via that injector?

[modok]

Based on the tone of what you wrote.... I am assuming you think this behavior is a malfunction. It isn't.

This is something that happens when carburetors get hot.

It's the same way a mr. coffee machine works
Also how a steam tube toy boats work
https://en.wikipedia.org/wiki/Pop_pop_boat


You can add features to the carburetor to prevent it doing that.
You can use insulators to lessen how hot the carbs get
You can add a vapor recovery system to absorb the fuel vapors.
Or just realize that back in the day people didn't park thier cars indoors on clean concrete....sorry this isn't that kind of vehicle

But, thing is I don't know if you have a problem of if you just alarmed at the reality. Why does my clear fuel filter has a bubble inside? or, why does it idle on two cylinders.... Just messin with you.

Maybe the carbs are too hot, or, maybe they aren't. You can check the fuel pressure. You can check how hot the carbs are. Maybe it needs some improvement but maybe not.

[MonsterMovie]

[busdaddy]

If the throttle shafts were perfectly sealed that gas would just end up in the engine, either way it's a bad deal.

You mention "rebuilt" carbs, did you do it?, or someone else?, did you (or they) install the needle and seat that came in the "kit"?, or re use the originals?
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[MonsterMovie]

[modok]

I see. In that case the float bowl must be overfilled. So, look for why

[MonsterMovie]

[Zed999]

There's a plastic piece that fits over the float hinge. It kind of looks right when it's the wrong way up but when it's upside down it stops the floats floating high enough to cut off the fuel. Worth a look as both carbs were apart and both now over filling.

[FreeBug]

If you can givea precise id of the carbs/engine, I can tell you exactly what thickness of washer(s) to put on the needle valves, ifit's a stock setup.

Type 3s had a weird thingy in the fuel T. I never really understood what it does, but it probably does sometning.

[Ohio Tom]

[MonsterMovie]

[Frank Bassman]

Add a fuel t before and after the fuel pump. Connect a fuel hose that goes from inlet to outlet of pump with a very tiny restrictor inside. (AmI think I used the smallest weber ict jet I could find.)

When engine is hot fuel pressure builds in the lines. This floods engines. Adding this small restricted "bypass" allows the pressure that builds from pump to carb/s to escape to the line just before the pump.

Cured my flooding while parked issues. Yes bad needle seats do this but when 4 of them do it you start finding alternatives


The fuel pressure loss is almost non existent while running with the restrictor.

Worked for my brazil PDSITs and now with my 34 pict too.


-Frank

[Slow 1200]

carb gaskets these days are way thicker than the originals, so you have to compensate for that with thicker washers under the needle and seat,which by the way are pretty bad in most rebuild kits too

[FreeBug]

[MonsterMovie]

[modok]

no washers? Oops.
The solexes do not have an easy way to set the float level, but it still needs to be set right.... as is true with any carburetor.
If there was an easy trick to do it I'd tell you, but I don't know of one.

May have HOLD the float against the lid, balanced on top if the silly plastic spacer thing, and figure out the right thickness of washer to use to get the relationship right.

tho one thing kinda odd about the whole thing is......IF the fuel level is too high.....why is the fuel coming out the acc pump and high speed enrichment nozzle? I would think it would just come out of the main nozzle.

[FreeBug]

Are you talking about a red fiber washer? That's for the float bowl drain/main jet access plug.

[MonsterMovie]

Updates:

Right Carb ID: VW41-2 6780644
Left Carb ID: VW 98-1 B 6 334

See a video of the carbs leaking here: https://youtu.be/oYbMzHxFn5U

Fuel pressure = 6psi when idling typically.

What's a good pressure regulator for these cars? I see the EMPI is a POS.

[chrisflstf]

I would start at 3

[modok]

The fuel pump IS the regulator.
It should be 3-4psi.
If the pressure is too high check the pushrod height.
If that is Ok take it apart and shorten the spring.
https://carterengineered.com/mechanical-fuel-pump-m60175