Carb flooding

[johnny diamond]

I have a brand new cd 175 here carefully stripped and checked over as it's new old stock...but all fine, if I use choke it flood's,! if I manage to start car without choke and get it warm it run's perfect and tick's over nicely, but if I switch it off and then attempt to start it again it instantly flood's float's are fine and set correctly and needle is down to it's leanest point,and I am running out of idea's of how it can continue to flood,!! any idea's,?

[Clan]

Originally Posted by johnny diamond

I have a brand new cd 175 here carefully stripped and checked over as it's new old stock...but all fine, if I use choke it flood's,! if I manage to start car without choke and get it warm it run's perfect and tick's over nicely, but if I switch it off and then attempt to start it again it instantly flood's float's are fine and set correctly and needle is down to it's leanest point,and I am running out of idea's of how it can continue to flood,!! any idea's,?

Flooding is down to either a worn or faulty needle valve or excessive fuel pressure , should be around 3 psi .was it the genuine volvo emission carb or a general CD175? Adjusting the needle will have no effect on float level . you don't have the Pierburg/ Stromberg carb with the flat metal float chamber base do you?

[johnny diamond]

it is flat, with a slightly protruding centre as you look up from underneath,I have re adjusted the float tab and now the engine run's but left on tick over it will cut out after a min, I have ordered a pressure gauge and regulator as I had suspected too high pump pressure so will test that before proceeding. what is the significance of the flat bottomed float chamber Clan,??

[Clan]

Originally Posted by johnny diamond

it is flat, with a slightly protruding centre as you look up from underneath,I have re adjusted the float tab and now the engine run's but left on tick over it will cut out after a min, I have ordered a pressure gauge and regulator as I had suspected too high pump pressure so will test that before proceeding. what is the significance of the flat bottomed float chamber Clan,??

It is pierberg then, a 2.3 engine around 1979? The most trouble some carb, when neglected , It will need a new white plastic float retaining bracket, needle and jet, and that black U shape small bore pipe on the outside and the valve it fits to,
and float chamber gasket of course.

[geoffo]

Hi does it do warm start ok or not? If not it’s the overheat valve thing inside the yellow plastic arm on the outside of the carb. Ive had issues with this! I took it off cleaned it and there’s a bi metallic strip to have a guess at the setting. So far so moderate 🤣

[Clan]

Originally Posted by geoffo

Hi does it do warm start ok or not? If not it’s the overheat valve thing inside the yellow plastic arm on the outside of the carb. Ive had issues with this! I took it off cleaned it and there’s a bi metallic strip to have a guess at the setting. So far so moderate 🤣

That valve is a temperature compensator, when the fuel gets hot it runs richer so that valve bleeds some air in to weaken off the mixture when the carb gets hot.

[wisty]

Originally Posted by Clan

That valve is a temperature compensator, when the fuel gets hot it runs richer so that valve bleeds some air in to weaken off the mixture when the carb gets hot.

The most trouble some carb, when neglected , It will need a new white plastic float retaining bracket, needle and jet, and that black U shape small bore pipe on the outside and the valve it fits to,

Hi Clan. I have the same carb. Do you know where I could source the float retaining bracket please? Best wishes Wisty

[Clan]

Originally Posted by wisty

The most trouble some carb, when neglected , It will need a new white plastic float retaining bracket, needle and jet, and that black U shape small bore pipe on the outside and the valve it fits to,

Hi Clan. I have the same carb. Do you know where I could source the float retaining bracket please? Best wishes Wisty

Your volvo dealer I would say! its been over 20 years since I last overhauled The Pierburg ( NOT stromberg) one but did dozens back when the cars were current . I would change all the parts I mentioned in my old post above.