I've asked everywhere else so...

[Mikez73]

Why not here. I rebuilt my Weber DCOE40 18 carbs. One of them leaks fuel out the horns, mostly the right barrel. All the obvious possibilities have been checked. No, the intake valves aren't sticking. Yes, the floats are adjusted and are functioning. The needle valve is fine. The venturi's are snug and secure.

I've asked and searched at HZ and tried google and sent emails to Weber shops and tech forums.

[d240zx2]

One possibility comes to mind: a crack in the housing.

[Mikez73]

I suppose that could possibly cause an internal leak but the body isn't cracked. I considered listing that as one of the obvious but already checked and discarded possibilities. BTW the fuel pressure is 3psi so that's another obvious possibility that has been crossed off the list. I'm stumped and apparently everyone else is too

[cygnusx1]

I am following this thread here too. Mine leaks occasionally and when I searched the topic ad-nauseum a few months ago, I came to dead ends...other than the obvious, which we already covered.

One more thought? Vibration and mounting angle might affect it...

When I had the chokes out of the carb, I realized that there is no true seal in the channel that runs from the bowls down into the aux venturi. Fuel could easily leak from that interface.

Edited August 30, 2010 by cygnusx1

[Mikez73]

I am following this thread here too. Mine leaks occasionally and when I searched the topic ad-nauseum a few months ago, I came to dead ends...other than the obvious, which we already covered.

One more thought? Vibration and mounting angle might affect it...

When I had the chokes out of the carb, I realized that there is no true seal in the channel that runs from the bowls down into the aux venturi. Fuel could easily leak from that interface.

Yeah that's odd isn't it. I searched for hours on google and read through threads from all kinds of car (and motorcycle) models that use Weber carbs...Porsche, Alfa, Lotus, Jeep, Harley etc etc. Quite a few leak situations but none were quite right.

I thought about mounting angle but I can't see how that carb would be much different from the others.

The aux venturi was one of my first suspects.. The aux venturi's in that carb are new and they are the set screw type. I modified them to use the springs from my melted aux venturi's so I thought that may have caused the problem. I switched the one from the leaking carb to a non-leaker and nothing changed.

I thought about the idle mixture screws too. I installed the new style screws that came with the service kits. But...I used the new style screw in the non leaking carbs too so that's not it either.

I'm wondering about the accelerator pump stroke too. Maybe there is still fuel squirting out after the throttle plate closes. I don't have my manual right now but I remember reading about checking the stroke. Not sure how you'd adjust that though.

I'm going to go over the illustrations at the Teglerizer site again and trace the fuel flow from the carb filter to the throttle plate and look for any possible leak sources. If I have any luck I'll post up what I find. I'm not feeling really optimistic though.

[Nigel1943]

Why not here. I rebuilt my Weber DCOE40 18 carbs. One of them leaks fuel out the horns, mostly the right barrel. All the obvious possibilities have been checked. No, the intake valves aren't sticking. Yes, the floats are adjusted and are functioning. The needle valve is fine. The venturi's are snug and secure.

I've asked and searched at HZ and tried google and sent emails to Weber shops and tech forums.

Have you had the lid off the offending carb after running to see if its overfilling. There are 5 different needle valves for the DCOE and also a viton tipped one. I would suspect it's the needle valve that's causing the problem.

[ChrisZ]

Have you had the lid off the offending carb after running to see if its overfilling. There are 5 different needle valves for the DCOE and also a viton tipped one. I would suspect it's the needle valve that's causing the problem.

I'm thinking the same and would also like to know how you adjust the float level.

Chris

[Mikez73]

Have you had the lid off the offending carb after running to see if its overfilling. There are 5 different needle valves for the DCOE and also a viton tipped one. I would suspect it's the needle valve that's causing the problem.

I thought I'd already covered that? To answer your question...yes I've had the cover off after running. The level in the bowl is fine. The floats are dead on both at the top of their stroke and the low end.

I'm thinking the same and would also like to know how you adjust the float level.

Chris

There are two tabs on the float device that contact the needle valve housing. One tab for the lower end of the stroke and one for the upper end. You don't want too much fuel in the bowl but you don't want too little either. You set the floats by manipulating those tabs. Pretty basic.

[ChrisZ]

And how do you measure it, how do you know you have the right float high?

Chris

[Mikez73]

And how do you measure it, how do you know you have the right float high?

Chris

Are you seeking information or are you wondering if I set the floats correctly?

DCOE40 18 brass floats. 8.5mm at the top of the stroke and 15mm at the bottom.

http://www.piercemanifolds.com/category_s/317.htm

[ChrisZ]

So you haven't tried to measure the actual level in the bowls

[Mikez73]

So you haven't tried to measure the actual level in the bowls

Yes Chris I have. As I said, the floats are adjusted and functioning.

Thanks for the input.