Lancia Motor Club

Model Technical and Interest => Fulvia => Topic started by: Keithver on 16 September, 2024, 11:54:16 AM



Title: carb leak
Post by: Keithver on 16 September, 2024, 11:54:16 AM
Hi. When my S2 has been sitting for more than a day, it takes a good minute of cranking to get it started.
My feeling is that the petrol was draining out of the carbs and the pump had to re-fill them before it would fire.
There doesn't seem to be a petrol smell or evidence of a leak below the car.
I noticed (in sunlight) that the carbs were both wet, See the photo. You can see the curve of fuel below the SOLEX name. Having a closer look there is fuel on the top of the carb too.
The carbs were rebuild before going back into the car.
Admittedly the tops have been removed a number of times to get the carbs right.
Could it be damaged gaskets. should I replace them or is there another possible cause


Title: Re: carb leak
Post by: lancialulu on 16 September, 2024, 12:40:51 PM
Keith

That leak needs sorting but it will not explain poor starting as the fuel level is normally below that gasket level. Almost all Fulvias seem to lose fuel if the car has not been used. I always advise fitteing a Facet cube (little) electric pump in series (before the mechanical pump) to prime if the car has been standing.

In most cases there is evidence of a tiny leak at the bottom gaskets which is so small it evaporates before leaving a puddle on the drip tray. (Thats my theory).


Title: Re: carb leak
Post by: fay66 on 17 September, 2024, 08:43:04 PM
Keith

That leak needs sorting but it will not explain poor starting as the fuel level is normally below that gasket level. Almost all Fulvias seem to lose fuel if the car has not been used. I always advise fitteing a Facet cube (little) electric pump in series (before the mechanical pump) to prime if the car has been standing.

In most cases there is evidence of a tiny leak at the bottom gaskets which is so small it evaporates before leaving a puddle on the drip tray. (Thats my theory).
I fitted a priming pump to my fulvia 2c best part of 20 years ago, I also have a filter king pressure regulator, originally I had solex 32s,  that I replaced with Dellorto 32's, but it's still the same.
Much easier to fit a priming pump and forget the starting problems.
Brian
8227 8)


Title: Re: carb leak
Post by: robupton on 18 September, 2024, 10:35:06 PM
When I first got my Fulvia I had a significant amount of fuel coming out of the top of the carbs. On investigation replacing the very small O rings on the brass plugs under the top cover solved the problem.
When you carbs were rebuilt perhaps these were overlooked or damaged in replacement?
 


Title: Re: carb leak
Post by: Keithver on 19 September, 2024, 06:52:24 AM
Thanks for all of your input and ideas everyone. Rob, I'll check those tiny rubber o-rings
Someone else suggested connecting a priming pump up to the choke switch. Seems like a neat solution :)


Title: Re: carb leak
Post by: Wangler on 19 September, 2024, 07:35:57 AM
When I first got my Fulvia I had a significant amount of fuel coming out of the top of the carbs. On investigation replacing the very small O rings on the brass plugs under the top cover solved the problem.
When you carbs were rebuilt perhaps these were overlooked or damaged in replacement?
  
Very interesting. I have a similar problem. The area around the top plates on mine always has an oily sheen. I put new gaskets around the plates but it didn’t make much difference. What are the round brass “plugs” for? (I assume you are referring to the things attached to the plates) Where did you get the O rings?


Title: Re: carb leak
Post by: Keithver on 19 September, 2024, 08:09:12 AM
I presume Rob is talking about part 44 which goes onto part 84 in attached diag (TAV 13) from the parts book. Are they standard rubber O-rings though, or do they need to be petrol resistant


Title: Re: carb leak
Post by: Wangler on 19 September, 2024, 08:24:27 AM
Ah! I thought that Rob was talking about the part I’ve highlighted. I would still like to know what this brass thing does.


Title: Re: carb leak
Post by: Keithver on 19 September, 2024, 09:11:36 AM
They are to do with the accelerator pump, I think


Title: Re: carb leak
Post by: lancialulu on 19 September, 2024, 09:47:29 AM
They are to do with the accelerator pump, I think
Correct.


Title: Re: carb leak
Post by: Wangler on 19 September, 2024, 12:14:02 PM
They are to do with the accelerator pump, I think
Correct.

Fair enough, but what do they do and how?


Title: Re: carb leak
Post by: dhla40 on 19 September, 2024, 05:44:52 PM
They are plugs to make sure the fuel from the accel pump goes to the jets, the weight and ball under them act as a one way valve. The metal thing on the top cover is part of the float chamber vent system.

Sean


Title: Re: carb leak
Post by: Wangler on 19 September, 2024, 06:58:30 PM
They are plugs to make sure the fuel from the accel pump goes to the jets, the weight and ball under them act as a one way valve. The metal thing on the top cover is part of the float chamber vent system.

Sean

Thanks Sean, I know my float levels are much too high so that explains where any spillage gets out and causes the oily looking stains (partially dried petrol) in that area.