Amazon: SU Carbs overflowing

[Relentless]

Hi all, over the weekend the float chambers for both SU carbs on my 63 B18 122s have started flooding and pouring fuel out of the top. I have no experience stripping and rebuilding carbs nor do I know when the carbs were last serviced if at all. so does anyone know of anyone in around the Portsmouth/Southampton area? Or even any hints and tips on how an inexperience baboon such as myself could investigate further?

[Rustinmotion]

Originally Posted by Relentless

Hi all, over the weekend the float chambers for both SU carbs on my 63 B18 122s have started flooding and pouring fuel out of the top. I have no experience stripping and rebuilding carbs nor do I know when the carbs were last serviced if at all. so does anyone know of anyone in around the Portsmouth/Southampton area? Or even any hints and tips on how an inexperience baboon such as myself could investigate further?

I’d guess it’s punctured floats or sticking/ worn needle valves you can see on the photo, if you pm me your email address il send you an SU service manual, accessing the floats is a simple job
Are you using E10 fuel? I think the old floats are not compatible and this could be why they have both started misbehaving some seem ok with E10 others degrade

[Relentless]

Originally Posted by Rustinmotion

I’d guess it’s punctured floats or sticking/ worn needle valves you can see on the photo, if you pm me your email address il send you an SU service manual, accessing the floats is a simple job
Are you using E10 fuel? I think the old floats are not compatible and this could be why they have both started misbehaving some seem ok with E10 others degrade

That would be awesome thank you! I always steer away from E10 but no idea what my wifes grandfather who owner it before i saved it used. I will PM my details once ive hit the required 30 posts .... lol got to love rules

[Rustinmotion]

While you build up your posts this will help from Swedish Embassy

https://www.sw-em.com/SU%20Carb%20Se...b_Service_Lite

[Othen]

This may help OP (see att).

[Ron Kwas]

Rele;

Welcome to this forum!

Overflowing carbs are a disconcerting first impression with your vintage Volvo, but also not too difficult to address and sort for a careful hands-on owner...and if this is you first experience with the wonderful SU carbs, familiarizing yourself is a good and recommended start! See link RiM has already posted (and thanks for reference!)

Good Hunting from Connecticut!

[142 Guy]

Leaking floats that have lost their buoyancy will certainly cause flooding of the float bowls; however, it is a bit unusual that both floats would develop leaks at exactly the same time. It is more likely that you have sucked up some crud in the fuel which has lodged itself in the needle valves controlled by the floats. Either way, the float bowls have to come off to repair / replace the floats or clean out the needle valves. While apart, replacing the actual needle valve itself might be good preventative maintenance - the viton tips don't last forever.

If the problem is the floats then repair or replace (remember that the float level has to be checked / set after doing this) and you are likely done. If it was crud in the needle valve you might want to give consideration as to where the crud came from. There might be more crud in the fuel line and the fuel tank just waiting to enter the needle valves and plug them again leading to a recurring maintenance problem. If you have a good micronic in-line fuel filter that would normally block anything large enough to cause needle problems. If you are running one of those mesh lump screens, then you might want to consider a more general fuel system clean out or at least switch to a micronic filter which block lumps from entering the needle valve.

[buick boy]

Both carbs going faulty at the same time? .Had a similar problem many moon's ago with su carbs . It turned out to be high fuel pressure caused by a faulty mechanical fuel pump . It might be worth measuring the fuel pressure so as to eliminate it as a cause before stripping the carbs.

[amazon69]

Good point re both going at the same time. When my 1800 did that it was because the fuel line post pump was a bit squeezed, increasing pressure at the carbs, causing them to overflow. Worth a look, probably wise to change those rubber lines to e10 proof stuff.

[142 Guy]

High fuel pressure can certainly cause fuel bowl flooding. I have to admit that a fuel pump failing in a mode that resulted in high pressure wasn't in my mental encyclopedia of possible causes.