TheSamba.com :: View topic - HELP please my carb is filling with gas and i dont know why?

Thu Jun 03, 2010 5:39 pm

so occasionally i can hear gurggling coming from the right side carb on my 69 squareback. I looked and the carb was filling up with gas above the bottom butterfly. the jet isnt the issue its not leaking the fuel its coming from somewhere else. I had this problem before and I was smelling gas coming from the enigne area of the car and i took the carbs off rebuilt them, made sure the needle valves were working correctly and and adjusted the fuel float. well I am experiencing this again, and am stumped now.

I need some help with this as it is supposed to be a daily driver.

the carb set up is the dual empi 34 kit with out chokes. I am really starting to hate these carbs but cant spend money for something else and need to make these work for a bit.

please help me, thanks!!

Thu Jun 03, 2010 6:09 pm

What fuel pump are you using?

I had a similar issue with an electric pump pushing fuel past the needle valves.
Swapped to a mechanical pump and haven't had an issue since.

The electric pumps pump the same regardless of RPM, whereas a mechanical pump wll deliver less fuel at idle and more at higher RPM when the engine is using more fuel.

Thu Jun 03, 2010 11:08 pm

I have a stock type mechanical fuel pump but no fuel pressure regulator. Could the stock type pump still be putting of to much fuel pressure?
The fuel filling in the carb happens after I turn the motor off, that's when I hear/see the fuel filling the passenger side carb. It only happens to the passenger side carb too.

Fri Jun 04, 2010 7:17 am

Bad needle and seat. Plus, which "stock" fuel pump do you have?
One of the gold colored Brazilians, or an old style?

Fri Jun 04, 2010 9:44 am

I just rebuilt these carbs about 1 and a half months ago can the needle and seat valve be bad already??
And I have the brazillian gold colored fuel pump on it.

Fri Jun 04, 2010 11:30 am

You need to check you pressure. I have the same pump on mine and I ended up using a thicker gasket to get my pressure around 3psi currently. I had a problem with my carbs boiling over as well and I changed to a set of NGK plugs and used the thick fiber gaskets for the manifolds and I have not had the problem again so fare.

Fri Jun 04, 2010 12:00 pm

The last "stock" pump I bought was putting out over 6 PSI at 1000 rpm it lasted about a month and took a crap. :evil: .

Fri Jun 04, 2010 12:23 pm

Sounds like I should check my fuel pressure. I've never checked fuel pressure before how exactly is it done? Do you need a special gauge to do so?
Thanks for all the help so far, I'm still learning these cars but loving it

Fri Jun 04, 2010 12:26 pm

Was the carb leaking before you rebuilt them? Bobnotch says the needle/seat in the Rebuild Kits are crap and reuses his old ones.

Fri Jun 04, 2010 12:37 pm

Quote: I've never checked fuel pressure before how exactly is it done?

the FLAPS should have a kit for $10 or so, gauge, tee, chunk of hose.
Tee it into the supply line and run it.

Fri Jun 04, 2010 1:00 pm

Exactly $14 at Autozone. Do the stock rebuildable style pumps put out better psi in the proper range? I have been thinking about trying one of the extra ones I have laying around out and see where it is at.

Fri Jun 04, 2010 1:37 pm

I used to rebuild early style pumps, but the kits that are available now days, are junk, and have quit doing them.

Fri Jun 04, 2010 2:15 pm

77ducci wrote: I had a problem with my carbs boiling over as well and I changed to a set of NGK plugs and used the thick fiber gaskets for the manifolds and I have not had the problem again so fare.

asesapie wrote: I just rebuilt these carbs about 1 and a half months ago can the needle and seat valve be bad already??
Hey asesapie, does this happen when the engine is still cold?

If so, I would lean towards a fuel-pressure or float valve problem.

If it only happens when the engine is hot, I'd say you are boiling the fuel in the carb.

1-1/2 months ago, the weather was cooler, right?

Max

Fri Jun 04, 2010 5:38 pm

Yeah I'll have to put the old needle and seat back in since I was smart and saved those.

And yes it was colder out a month and a half ago but it happens after I have driven the car for a bit like 15 min. or so maybe longer and it doesn't happen every time. So I guess that would be after the car is warmed up. What do you mean by boiling the fuel?

Fri Jun 04, 2010 6:07 pm

The heads may be getting hot enough to get the carbs hot enough to boil the fuel in the bowls.

A fuel pressure issue should show up right away after the engine is started. If that isn't happening, I don't see how it could be fuel pressure.

Max

Fri Jun 04, 2010 6:53 pm

Huh well the gurggling/filling of the carbs I can see when I take the air filter off the carb and look down it there is fuel puddling up above the butterfly.
Does that sound like boiling or fuel pressure?

I guess I'll check my fuel pressure tonight and see if that's what's happening.

Fri Jun 04, 2010 7:11 pm

asesapie wrote: Huh well the gurggling/filling of the carbs I can see when I take the air filter off the carb and look down it there is fuel puddling up above the butterfly.
Does that sound like boiling or fuel pressure?
Tell me if it happens when the engine is cold and I'll tell you.

Max

Fri Jun 04, 2010 8:33 pm

ok will do. but i just tested the fuel pressure and found that it is putting off about 6 psi to the carbs. so i believe it needs to be at 3psi for these. so is it best to shim it or to put a regulator in the line? and how do you shim if shimming is the easy effective method?
thanks for your help so far

Fri Jun 04, 2010 8:54 pm

Adding gaskets is supposed to reduce the pressure. So add a gasket and recheck the pressure. Repeat until you get the reduction you are looking for.

Max

Sat Jun 05, 2010 6:09 am

You'll need a pile of stock thickness gaskets to get it down to 3 PSI, or use thicker gasket material, ours was 1/8 or 3/16" thick to get the pressure down enough to run 2.5 PSI.