Why Does My 34 PICT 3 Flood After Shutdown?

Carbs & F.I.

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vwlover77
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Post by vwlover77 » Mon Mar 30, 2009 9:12 am

Latest post of the previous page:

I replaced the original fuel pump a couple of years ago as it was leaking fuel out of the base. The current pump is the Mexican Bocar variety (angled for alternator-equipped vehicles).

I currently have the typical clear plastic fuel filter installed between the pump and carb.

The current needle valve has Solex stamped on it, and appears to be 100% brass. It's built such that I can actually see the needle fill the hole when it's in the closed position and viewed from the inlet side.

I'll certainly try the fuel line clamp the next time I get the car out. Not today! Brrr... It's only 35 degrees!
Don

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78 Westy
71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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hambone
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Post by hambone » Mon Mar 30, 2009 9:47 am

You might want to check the pressure again, I had the same problem but shims fixed it.
Maybe you just need to get that tired ol' carb rebuilt by Keith.
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vwlover77
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Post by vwlover77 » Fri Apr 24, 2009 6:25 pm

It was 80 degrees here today so I got the Beetle out for a top-down ride. Got it good and warm and when I got home and shut it off, I immediately clamped the fuel line between the pump and carb.

No difference. After half an hour or so, I pulled off the air cleaner and looked down the throat to see the throttle plate soaking wet with gas. The end of the throttle shaft had drops on them too.

Maybe a carb rebuild with a new top gasket is the best place to start?
Don

---------------------------
78 Westy
71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Amskeptic
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Post by Amskeptic » Fri Apr 24, 2009 7:06 pm

vwlover77 wrote:It was 80 degrees here today so I got the Beetle out for a top-down ride. Got it good and warm and when I got home and shut it off, I immediately clamped the fuel line between the pump and carb.

No difference. After half an hour or so, I pulled off the air cleaner and looked down the throat to see the throttle plate soaking wet with gas. The end of the throttle shaft had drops on them too.

Maybe a carb rebuild with a new top gasket is the best place to start?
Take the fuel line off to verify that you have stopped the fuel flow. . . . carefully with a hot engine. Free the fuel line from the carb then stick it back on in the morning while the engine is cool so you have a better time of it when it is warm. Clamping it may not be sufficient.
Colin
BobD - 1978 Bus . . . . . . . . . . .111,130 miles
Chloe - 1970 bus . . . . . . . . . . . 206,787 miles
Naranja - 1977 Westfalia . . . . . 93,996 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 72,113 miles

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spiffy
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Post by spiffy » Fri Apr 24, 2009 10:11 pm

I would take the carb off (two bolts and two screws) empty it out and check the thang (sorry, don' t know the technical term) at the bottom of the bowl....that thing can leak. Either way get a quality rebuild kit for $40 and get all the carb internals to YOUR standard. If you "rebuild" it and you still run into problems despite due diligence then look at the TS bushings. A single carb is THE simplest form of induction, figuring out the "voodoo" is fairly simple as the problem can only exist in an object smaller then a pint of beer.
78 Riviera "Spiffy"
67 Riviera "Bill"

vdubyah73
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Post by vdubyah73 » Sat Apr 25, 2009 4:45 am

On the top of the carb body, under the top that is removable to get at the float bowl, are a couple of holes where the gasket sits. They may be plugged up or the wrong gasket may have been used and is covering them. I believe they are vents for the carb. when you shut it off the gas expands from the heat rising off the engine and has nowhere to go. So it pushes out through the accelerator pump and down the throat.

This is a guess but worth popping the top off and looking.
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Amskeptic
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Post by Amskeptic » Sat Apr 25, 2009 7:09 pm

vdubyah73 wrote:On the top of the carb body, under the top that is removable to get at the float bowl, are a couple of holes where the gasket sits. They may be plugged up or the wrong gasket may have been used and is covering them. I believe they are vents for the carb. when you shut it off the gas expands from the heat rising off the engine and has nowhere to go. So it pushes out through the accelerator pump and down the throat.

This is a guess but worth popping the top off and looking.
There is a diagonal tube right next to the choke plate that goes to the ceiling of the float chamber. That that tube is the "vent."

Bentley is pretty stubborn about difficult hot starts, "it's the needle valve" they say. They are silent about the benefits of the anti-percolation valve on the fuel pumps of the later carbureted Volkswagens.
Colin
BobD - 1978 Bus . . . . . . . . . . .111,130 miles
Chloe - 1970 bus . . . . . . . . . . . 206,787 miles
Naranja - 1977 Westfalia . . . . . 93,996 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 72,113 miles

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Amskeptic
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Post by Amskeptic » Mon Jul 06, 2009 10:18 am

This punky summer so far has not given me an opportunity to really test the fuel pressure regulator as a hot-start improvement device, but so far it has done just that. 93* in Portland over the past couple of days and the bus started just fine. I will let you y'all know how it does if I can get down into the deserts over the next couple of weeks before they cool too much below 115*
Colin
BobD - 1978 Bus . . . . . . . . . . .111,130 miles
Chloe - 1970 bus . . . . . . . . . . . 206,787 miles
Naranja - 1977 Westfalia . . . . . 93,996 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 72,113 miles

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vwlover77
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Post by vwlover77 » Sat Jul 31, 2010 6:24 pm

Well, it's been a while, but here's an update. I had the carb bushings replaced by Krusty Karb Keith, cleaned all carb passages and jets, cleaned and checked the needle valve (it's fine), and installed an adjustable fuel pressure regulator in the fuel line between the pump and the carb (as close to the carb inlet as I could get it.)

With the pressure set to 1/2 PSI (as low as it will go), the engine runs fine, but the carb still floods during the heat-soak after shutdown. The only good news is that fuel no longer drips from the ends of the throttle shaft thanks to the new bushings.

I'm thinking of installing an electric fuel cutoff valve in the inlet line to the carb. Here's my reasoning: The fuel that is emptied out of the bowl during the heat-soak will cause the float to drop, allowing more fuel under residual pressure to refill the bowl, providing more fuel to "boil over" into the carb throat. With a cutoff valve, at least the flood will be limited to only the fuel in the bowl at shut down.

I'm thinking of one like this:
http://www.dan-marcrvparts.com/12vomufushof.html
Don

---------------------------
78 Westy
71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Amskeptic
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Post by Amskeptic » Sat Jul 31, 2010 10:19 pm

vwlover77 wrote:With the pressure set to 1/2 PSI (as low as it will go), the engine runs fine, but the carb still floods during the heat-soak after shutdown.
With a cutoff valve, at least the flood will be limited to only the fuel in the bowl at shut down.
My chromy deal on the Road Warrior actually helped prevent heat-induced percolation. Your float level was good?

I will be interested to know how the shut off works. Sounds good in theory.
Colin
BobD - 1978 Bus . . . . . . . . . . .111,130 miles
Chloe - 1970 bus . . . . . . . . . . . 206,787 miles
Naranja - 1977 Westfalia . . . . . 93,996 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 72,113 miles

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Hippie
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Post by Hippie » Sun Aug 01, 2010 1:56 pm

FWIW, I used to have a '50 DeSoto that did this no matter what I did to it.
I put some wooden clothes pins on the steel fuel line leading to the carb. That finally fixed her. I don't know if it was flooding or just vaporlocked, but the result was the same in hot weather.

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vwlover77
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Post by vwlover77 » Tue Aug 03, 2010 9:45 am

You lost me with the wooden clothespins.

Did you get 100mpg afterward? :geek:
Don

---------------------------
78 Westy
71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

vdubyah73
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Post by vdubyah73 » Tue Aug 03, 2010 4:55 pm

clothes pins are an old skool jury rig for vapor lock, as well as tin foil wrapped around the fuel line. Helps dissipate the heat.
Vapor lock is when the fuel boils in the line before the pump. The pump can't pump vapor very well and the bowl runs dry. If you have a dirty filter BEFORE the pump you will be more prone to vapor lock, as the pump is sucking harder to overcome the blockage creating lower pressure in the supply line. Lower pressure makes the gas boil at a lower temp.
1/20/2013 end of an error
never owned a gun. have fired a few.

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Gypsie
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Post by Gypsie » Tue Aug 03, 2010 9:36 pm

always a pleasure to read yer 'splanations, Dubya.
So it all started when I wanted to get better gas mileage....

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themarshotel7
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Re: Why Does My 34 PICT 3 Flood After Shutdown?

Post by themarshotel7 » Sat May 07, 2011 9:01 pm

Ok, I'm having the exact same problem with my 71 stock westy. Mine does not have to be hot to do it though, i can drive around the block when it's stone cold and after i shut it off, it slowly begins to drip. after several hours, it stops dripping. I even removed the top of the carb and it still drips from the throttle shaft. It's beginning to drive me crazy! It did not start doing this until after sitting for the winter. Please give me some idea's.

Ok, big update. I pulled the carb again cleaned it up and set it on the bench with the top off. I then put fuel in the carb and here's what I found.
Fuel slowly begins to seep out of the little pinholes (not sure what thier called) in the carb throat. Then running along the throttle plate and eventually out of the throttle shaft. Im guessing those are fed from the jet in the bowl through the emulsion tube?? Any thoughts?
1971 westfalia
1972 super beetle
1991 Fox
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Amskeptic
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Re: Why Does My 34 PICT 3 Flood After Shutdown?

Post by Amskeptic » Sun May 08, 2011 4:39 pm

themarshotel7 wrote:Ok, I'm having the exact same problem with my 71 stock westy. Mine does not have to be hot to do it though, i can drive around the block when it's stone cold and after i shut it off, it slowly begins to drip. after several hours, it stops dripping. I even removed the top of the carb and it still drips from the throttle shaft. It's beginning to drive me crazy! It did not start doing this until after sitting for the winter. Please give me some idea's.

Ok, big update. I pulled the carb again cleaned it up and set it on the bench with the top off. I then put fuel in the carb and here's what I found.
Fuel slowly begins to seep out of the little pinholes (not sure what thier called) in the carb throat. Then running along the throttle plate and eventually out of the throttle shaft. Im guessing those are fed from the jet in the bowl through the emulsion tube?? Any thoughts?
High float level or inadequate needle valve. Those are my thoughts.
Colin
BobD - 1978 Bus . . . . . . . . . . .111,130 miles
Chloe - 1970 bus . . . . . . . . . . . 206,787 miles
Naranja - 1977 Westfalia . . . . . 93,996 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 72,113 miles

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