My Carb Runneth Over

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Deacon
Posts: 6
Joined: Mon Mar 26, 2018 3:36 pm
Your car is a: 1977 Fiat Spider

My Carb Runneth Over

Post by Deacon »

I have a 77 Spider - original 32ADFA11 carb, electric fuel pump.

Current Problem: When I switch on the ignition, pump runs, secondary throttle barrel fills with fuel and carb soon starts to overflow, not from barrel, but from area/chamber beside access to air correctors/emulsion tubes. I have a photo, but can't figure out how to attach.

Background: Car sat a long time. I swapped fuel, new filter, new fluids, inspected lines, etc. and got it fired up pretty easily. Soon I heard, smelled and saw, a lot of fuel leaking beneath engine. It was leaking from charcoal vapor canister. Investigation showed fuel arriving at charcoal canister from the vapor line from the carb that attaches to middle of charcoal canister. Then I found it was leaking from the small gap/cavity immediately beside the chamber used to access air correctors/emulsion tubes. with fuel pump running, it bubbles up from the small gap and runs all over the place. So, I pulled carb and rebuilt it (replaced all gaskets and o-rings, new float needle valve, made sure float was properly adjusted) and thoroughly cleaned and inspected all parts. Reinstalled and it is still overflowing from the same place, though now it isn't flooding into the vapor canister (at least not before I switch off ignition to stop the pump). The fuel return line and check valve are not clogged.

Anyone have any thoughts or suggestions - other than replacing with a 34 ADF?

Thanks.
kmoses
Posts: 366
Joined: Thu Sep 11, 2014 10:28 pm
Your car is a: 1979 Spider 2000

Re: My Carb Runneth Over

Post by kmoses »

It could be the wrong electric fuel pump (Webber carb. only wants 3.5 psi at the carb.) or you could have a restriction in the return line. I would get 4' of fuel line and a empty 5 gal. gas can. Remove the return line from the carb. and replace it with the 4' line. Place the line end in the gas can and turn on the switch. If the carb doesn't over flow it is the return line. If it does overflow it is the carb float setting or fuel pump pressure.
Deacon
Posts: 6
Joined: Mon Mar 26, 2018 3:36 pm
Your car is a: 1977 Fiat Spider

Re: My Carb Runneth Over

Post by Deacon »

Kmoses:
Thanks for suggestions. I had already checked return line. It was clear and flowing and the carb is still flooding. Float was my thought too - and it seems the only thing it could be - but it is in good shape and hangs/floats within specs when I've got it out of car to measure. The pump is the same one I've had in there since 1996 and this is the first such instance, so I don't think that's it, though I can't be sure. I'm not much of a carb guy so pardon my terminology and/or knowledge. Should the secondary throttle barrel be filling with fuel like it was poured in from a cup? Shouldn't it be aerated fuel? I'm baffled.
samakijoe
Posts: 132
Joined: Wed Mar 15, 2017 9:56 pm
Your car is a: 1975 Fiat 124
Location: Original Washington (1776) NC

Re: My Carb Runneth Over

Post by samakijoe »

Everything I have read says the the fuel pressure for a Weber should be no more then 2.5 psi. 2psi is ideal.
Hard to find a 2 psi electric pump. Most use a pressure regulator and gauge to be sure. A car that sits for a long time will develop "varnish" anywhere the gas sits and goes dry over time.
You might pull the seat and clean the needle and the seat. Soaking it overnight might work. Nothing like a small sewing needle and a shot of high air pressure to clean the needle valve seat when "push comes to shove". Hold on to it (the seat) when you hit it with the air or be prepared to spend a good pit of time crawling around on your knees looking for it. :oops: (been there, done that)

Until you get the fuel to come into (and stop) the carb at/to the correct level nothing is going to be right. All the circuits rely on the correct level.

Here is a really good "how to" for Webers.

http://240260280.com/Tech/Carbs/Weber/D ... uning.html

Horizontal or vertical, all Webers work the same way......
SAMAKIJOE
AKA GRANDPA GRUMPYPANTS
kmoses
Posts: 366
Joined: Thu Sep 11, 2014 10:28 pm
Your car is a: 1979 Spider 2000

Re: My Carb Runneth Over

Post by kmoses »

Facet 40148 2.0-4.5 psi, 24 gal/hr works great with my 32 ADFA and 34 ADF. The Facet 40104 1.5-4.0 psi, 25 gal/hr that is listed as the stock replacement for my '79 fell flat at 5,000 rpm. I purchased the 40148 from Midwest-Bayless. I removed the 34 ADF due to low fuel mileage (could not keep my foot out of it).
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