Itinerant Air-Cooled

I got the '71 Beetle out of winter storage today. I've been having the problem of the carb flooding after the engine is shut off warm. So much so that drops of gas appear at the ends of the throttle shaft.

First, I shimmed the fuel pump with almost 1/4" more gasket thickness to reduce its pressure. Drove the car, shut it off, and pulled the air cleaner off after about 15 minutes. The throttle plate was soaked in gas. So, I pulled the fuel hose off the carb inlet. No pressure relief squirt when I did that. I don't know if that's a good or bad thing.

Next, I carefully removed the top of the carb. The fuel level in the bowl was nowhere near the top, but I added another washer under the needle valve (which seemed to be working fine) for good measure.

No improvement. It seems like the fuel is leaking down into the throat from the air correction jet on the top of emulsion tube, or one of the two drillings with brass inserts that are just clockwise from the emulsion tube (when looking at the carb from the rear of the car).

Any suggestions?

Thanks!

Run some fuel system cleaner with your gas for a tank or 2. Easy and cheap first, before you go tearing things apart. Your beetle still has sleep in its eyes.

Hiya Don,

Not that this would have any effect on your current situation, but I was curious, do you have an AutoStick specific 34PICT3?

Bookwus wrote:Not that this would have any effect on your current situation, but I was curious, do you have an AutoStick specific 34PICT3?

Well, I guess I do. It is the original factory Solex carb. As far as I can tell, the only difference between it and a "regular" 34 PICT 3 is the small hose connection (right next to the vacuum retard connection) that runs to the AutoStick control valve on the left side of the engine compartment.

Hiya Don,

Sounds like an AutoStick carburetor.

If it is AS and original to 1971 it should have 281-1 stamped into the base flange.

And if it is original to the car, I'm wondering if the throttle shaft might need rebushing. Possible?

Actually, it is stamped with "VW 281_2". It is the original carb, as far as I know, but the car has only 88,000 original miles. The bushings could be worn, but in any case I don't think all the fuel I'm seeing pooling up on the throttle plate is normal.

Hiya Don,

281-2 would have been a 1972 production carb for a federal AutoStick.

ps......it would have been identical to the 281-1 in '71 except for one thing. The 281-2 would have run a 127.5 main jet. The 281-1 ran a 130 main

Interesting... It certainly could have been replaced by a previous owner. We bought the car in 1990. The car's date of manufacture is Feb '71 per the door jamb sticker.

I wonder if the heat soak after shutdown makes fuel boil up through the carb passages and into the throat. Last Fall, I got one of the brand new EMPI 34 PICT 3 carbs on store credit from the shop that botched my Bus engine rebuild, and it leaked fuel from the ends of the throttle shafts after shutdown too! I ran that carb for all of an hour before deciding to sell it on eBay!

Oh, and as some insurance for my heads and to eliminate a slight acceleration bog, I run a 132.5 main jet. The one that came out was a 127.5

Hiya Don,

vwlover77 wrote:......I wonder if the heat soak after shutdown makes fuel boil up through the carb passages and into the throat. Last Fall, I got one of the brand new EMPI 34 PICT 3 carbs on store credit from the shop that botched my Bus engine rebuild, and it leaked fuel from the ends of the throttle shafts after shutdown too!....

If the inference here is that the EMPI made knockoff with less fine tolerances and materials is going to show heat soak related problems before a much better made Solex.....................I'm with you on that count.

vwlover77 wrote:I wonder if the heat soak after shutdown makes fuel boil up through the carb passages and into the throat.

I'm thinking so. If the fuel level in the bowl is right, maybe the bowl vent is plugged up.
Could be that the heat riser is staying too hot because of carbon buildup inside.
Is the fuel line running too near the hot parts?

Rob

Or your needle and seat are a bit gummy from it's winter sleep, with today's horrible gas in it, and all you need is to run some fuel system cleaner through it.

I checked out the needle and seat when I had the top off the carb - all seemed fine. The needle moved up and down very freely and seemed to seal off tightly. The bowl vent is wide open and clean.

Carbon buildup in the preheater tube could be an issue, I guess. I'm not sure I understand how this would cause higher temps than a wide open tube. The fuel line is routed well to the left of the carb and is all in the open away from "hot spots".

I had this same problem all last summer, so I don't think it's anything to do with it's hibernation.

Thanks!

vwlover77 wrote:I'm not sure I understand how this would cause higher temps than a wide open tube.

It won't. But it will stay hot longer after shut-off.
Pardon my poor wording before.

Rob

vwlover77 wrote: I had this same problem all last summer, so I don't think it's anything to do with it's hibernation.

Thanks!

VW was well-aware of this percolation issue. The original fuel pumps had anti-percolation valves at the top of the fuel pump. For fun, try clamping off the fuel line with a certified gentle clamp up near the carb and see if the throttle bushes/plate remain dry and the car starts normally.

If it does, would you be willing to experiment with a fuel filter between the pump and the carb to see if the filter acts as a pressure damper? I have always been curious about that. It could make it worse, the same, or better. I do not trust modern fuel blends with old-school newer neoprene needle valve seats. A good clean oem brass seat seems to do a good job, but hwere do you find them? I have the spring-loaded metal ball type needle valves and I have had a couple of shut-off fuel flood events that were easily attributed to crap in the carburetor. I also have the heat-soak hard-start issue but only when it gets near 100*. And that ain't happening this week.
Colin

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!