Stromberg Carburettor Flooding

[Guest]

Hope someone out there can help me - the carbs on my car flood petrol which escapes via the overflow pipe exiting at the front of the cylinder block. This has just started up, with no problems before, so I can't use the car until I can fix this as so much fuel comes out.
I have cleaned out the float chambers (hardly any sediment in there at all) renewed the drop down fuel inlet valves, renewed the plastic piston diaphragms, and the floats pivot freely. All to no avail. The inline fuel filters are clean, but am wondering whether the plastic fuel pipe from the engine bay filter to the carbs is breaking down internally and causing detritus to get stuck in the drop down fuel inlets keeping them open. Not done anything to this pipe in 25 years of ownership!
Or is it a fuel pump problem, just pumping too much fuel?

Robert Verrell

[martin]

Hope someone out there can help me - the carbs on my car flood petrol which escapes via the overflow pipe exiting at the front of the cylinder block. This has just started up, with no problems before, so I can't use the car until I can fix this as so much fuel comes out.
I have cleaned out the float chambers (hardly any sediment in there at all) renewed the drop down fuel inlet valves, renewed the plastic piston diaphragms, and the floats pivot freely. All to no avail. The inline fuel filters are clean, but am wondering whether the plastic fuel pipe from the engine bay filter to the carbs is breaking down internally and causing detritus to get stuck in the drop down fuel inlets keeping them open. Not done anything to this pipe in 25 years of ownership!
Or is it a fuel pump problem, just pumping too much fuel?

Robert Verrell

Hiya Robert, welcome to the forum. The usual culprit is the needle valves and still might be, changing the filter to carb pipes, as you suggest would be a good start. Sadly there are poor quality needle valves out there and replacement is no guarantee. Have you checked and set the float heights ? As you seem to have done everything else, that might well be the cause. To check the valves, drain all the petrol out of the carbs, invert them, and see if you can suck air through the petrol inlet pipe on each one, if you can, it / they have failed. There is a superior type of valve that uses a ball bearing instead of a pin. Do let us know how you get on. Cheers, and again, welcome. Martin.

[AlanD]

Hi Robert,
welcome to the club, i'm no expert on carbs, martin is very good so you have good advice there. you could try the buckeye triumph site, you google this, they have a really good book on there for the rebuilding of the carbs etc, it may help you, i have printed this off to keep, very informative. you will find plenty of experts on here, like Martin so i'm sure someone else will be along soon too

Alan

[Staggard]

Hiya Robert, welcome to the forum. The usual culprit is the needle valves and still might be, changing the filter to carb pipes, as you suggest would be a good start. Sadly there are poor quality needle valves out there and replacement is no guarantee. Have you checked and set the float heights ? As you seem to have done everything else, that might well be the cause. To check the valves, drain all the petrol out of the carbs, invert them, and see if you can suck air through the petrol inlet pipe on each one, if you can, it / they have failed. There is a superior type of valve that uses a ball bearing instead of a pin. Do let us know how you get on. Cheers, and again, welcome. Martin.

All that Martin said plus check you don't have a puntured float

[StagnJag]

Hi Robert,

Welcome to the Forum.

I have also heard of the float chamber gaskets being a bit wide and catching on the floats inside. That was on here quite recently.

Rgds

Dave

[Bob Heritage]

I have a Filter King fitted now which has a bigger filter plus a fuel pressure regulator. I fitted this after testing seven Stag pumps for pressure and they ranged from 1/2 lb to 8lb, you only need 2 1/2 to 3 lb with strombergs. With the Filter King you can adjust it to this setting. I think that if you have too much pump pressure it overcomes the needle valves.

[martin]

Out of curiosity Bob, where do you get your replacement filters ? after 15 months I think mine should be changed and they're a tad expensive from Malpassi. I think every Stag should be fitted with one, the accuracy and quality of pumps can't be guaranteed any more. Martin.

[V Mad]

I fitted this after testing seven Stag pumps for pressure and they ranged from 1/2 lb to 8lb,

8lb is way too much for most carbs. Bob, did you notice whether the ones with very high pressure were non-standard types? I would not have thought the SU pump would push out that much pressure.

[Bob Heritage]

I have not had to replace the filter yet Martin, but I would google it or e,bay it. I have the larger of the 2 filters and the price varied quite a bit between the different suppliers, in the end I paid £53 some were asking £70plus

[Bob Heritage]

Chris, the pumps were various makes but all taken from Stags. Interestingly enough even the one that produced 1/2lb still supplied enough fuel to run the car, probably not at speed though.

[martin]

I have not had to replace the filter yet Martin, but I would google it or e,bay it. I have the larger of the 2 filters and the price varied quite a bit between the different suppliers, in the end I paid £53 some were asking £70plus

I've got the FilterKing and the gauge, it's the replacement filters I'm after. Martin.

[Guest]

Hi Martin
Thanks for the advice, really impressed on such a speedy response.
I'll try what you suggest. Any ideas where I might get the ball bearing type of valves?
It seems to me with the amount of petrol flooding out chances are maybe sticking valves but you kind of dismiss that when you have just bought new one's!!
Robert

[V Mad]

Ah yes, various makes, thats not surprising then. I know some of the Facet pumps (and maybe some others) can put out a lot of pressure, but I am not aware of this problem with the SU.

Regarding the Stromberg needle valves, it seems surprising there are so many replacement ones that dont seem to work properly; I wonder if the spring is as strong as the original ones? If this was a lower spring rate, then it would be easier for the pump to overcome the valve.

[martin]

Hiya Robert, Moss Europe (Google) are the source of the needle valves, their called Grose-Jet, and are made for SUs and Zenith/Strombergs, make sure you order the right ones, the threads are different.
Chris, I don't believe the needle type contain a spring, just gravity.

[StagnJag]

I bought my replacement valves as part of a Zenith/Stromberg refurb kit, so presumably they were manufactured by Burlen to original spec. Maybe there is just a lot of rubbish copies out there at the moment. I have these and a new Burlen sourced SU pump.

Rgds

Dave