carb leaking fuel

[aerosilver]

Hi all,

Having started up my Stag for the first time after doing a hose replacement & coolant flush, I was alarmed to notice fuel dripping off of the back of the engine onto the drive. Investigation revealed that the fuel seems to be leaking out of the bottom of the RH carb and running along the vee. From what I could see the culprit is a leaky plug on the bottom of the float chamber, as it seems loose and I can spin it round with my fingers. The plug on the non-leaky LH carb is tight. I assume therefore I must have nudged it when replacing the coolant pipe to the heater.

I'm somewhat puzzled however because the repair manual shows this plug to be threaded - screwing in and sealing with an O ring, but unless it's sheared somehow or the thread is stripped, which I find hard to believe, the leaky one just goes round and round, and appears to have no thread.

Can anyone enlighten me on this one - I'm currently a novice as far as the carbs are concerned, and I'm hoping the fix is simply to whip off the carb assembly and replace the plug and O ring.

Thanks in advance.

Regards,

Bob
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[Chris810]

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Hi having had my car for over 22 years I had the carbs apart a number of years ago and from my memory the plugs on the bottom of the float chamber are a push fit with an o-ring as a seal I would remove the carb cluster complete with pedstal disturbing as little as possible and GENTLY prise the plug away from the housing, a new o-ring and replacement should be all that is needed, then as they say in all the best manuals "replacement is in the reverse order of removal"



Good luck



Chris

[stagstr]

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Hi Bob,

No replies for two days then two come all at once...just like buses eh?

I agree with Chris - the problem should only be the sealing ring - a new one should fix it. However, whilst you have removed the carbs from the pedestal I would be inclined to remove the float chamber, clean it out and check the height of the float assembly, and blow an airline through the needle valve.It's just another job out of the way. Maybe a future issue resolved before it becomes an issue.

Close inspection of my ROM and the Parts Catalogue show two different types of sealing plug. The ROM shows a threaded one, as you say, but the Parts Catalogue shows a push-fit version. Rimmers Bros catalogue is a copy of the Parts Catalogue version. Maybe you have the push fit which is why it's just turning round and round.

Hope that helps

Ray

[aerosilver]

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Thanks guys, that would explain it - I've looked at Rimmer's web site and see what you mean about the push fit plug, so have just ordered a replacement. I will just remove the whole carband pedestal assembly as I think the less I disturb the better, as it was running sweet as a nut before I discovered (caused) the leak!

Regards,

Bob

[aerosilver]

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I've just spent this afternoon whipping off the carb assembly and replacing the suspect float chamber plug and seal, and then putting it all back together again. but alas that would not seem to be the problem. I didn't even have to start the engine - just turned the key to the "ignition on" position so that the fuel pump clicked away, and after a few seconds there was a strong smell of fuel and it started dripping onto the drive from the bottom of the engine.

Much as I tried I could not see the source of the leak without whipping off the aircleaner box for a better view (which I haven't done yet), but wherever it is coming from, it's leaking at a fair rate and not just a drip. Can anyone suggest where the most likely source of the leak may be?

Cheers,

Bob.

[Guest]

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Amazing, my car has been in tucked in the garage for two weeks and it develops a fuel leak from the carbs too!! Mine is leaking from the LH carb float over flow. Ordered new gasket, plug seal and needle valve and will hopefully fix it tomorrow!

Try your float works correctly

Stan

[aerosilver]

imported post

Hi Stan,

Thanks for that, sounds like you and I may have the same problem as I have only recently acquired the car and it has had very little use over the last year or two, and none since Christmas, so things may have got a little sticky in the carb department. However I think I've reached the limit of my knowledge as far as the carbs are concerned so perhaps you could tell me how to check the float operation as you suggest - or point me somewhere which would enlighten me? I might add that when I changed the float chamber plug seal I also removed the bottom of the float chamber so I could check the inside - the float moved freely, although the bottom of the chamber had quite a lot of rust coloured powdery residue in, which quite surprised me, as I expected it to be clean(ish),so I cleaned it out. What would be the most common (or only) cause for the fuel to overflow - a sticking needle valve? If I replaced it as you seem to be doing, would it affect the carb tuning?

Sorry for all the questions but as a new Stag owner I'm keen to learn!

Bob.

[Guest]

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Today i have replaced the needle valve in my LH carb as this one was leaking from the over flow, it also had rusty coloured "stuff" in it. My right hand carb was leaking from the float chamber plug, i have fitted a new seal and cleaned out the chamber. You have to make sure that when the float is up ( full chamber) the flat part of the float is flat onto the needle, this pushed the needle up to stop more fuel entering the chamber. I checked this last week and decided my needle was duff so i replaced it. I suspect my right carb has been leaking for a while, i hope this reduces my woeful fuel consumption!!!

Stan

[Guest]

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Sorry forgot, the carb shouldnt need tuning. I am also new to stags, i had a simple MGB GT before!!

stan

[Guest]

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I have had trouble in the past with my carb(s) throwing petrol out when i have let my tank run low and sucking up crap in turn making its way to the needle valve. I have cleaned the tank right out but it still seems to find brown particles from somewhere.

[aerosilver]

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Thanks for the info. I think the logical next step then is for me to replace both needle valves (if one's become gunked up chances are the other one won't be far behind). While I've got the float chambers off I'll clean them thoroughly and blast everything through with some carb cleaner, and check the float adjustment. Hopefully that will sort it out. Off to Rimmers website now then............

Cheers,

Bob.

[Guest]

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well now, dont i feel a prat! As today was a sunshiney day i thought i'd take it out for a spin. 3 miles down the road it died on me. Lots of rusty crap in the fuel filter, car will start but wont rev. Enter flat bed to bring me home!! Will rip carbs apart next weekend and blow out all pipework from the tank, really cheesed off!!!! Still, at least the carbs dont leak!!

Stan

[aerosilver]

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Aww, that's bad news Stan.

Well here's my latest news and a warning to everyone.... I've spent this afternoon cleaning out the float chambers and renewing the needle valves to hopefully cure my overflow problem, but as soon as I removed the float chamber from the carb which I originally took apart to replace the plug seal, I saw what the problem was.... Doh!...

The float chamber gaskets supplied by Rimmers have an inward pointingtab in one corner (not present on the original gaskets I noticed). This tab does not seem to serve any purpose except to foul the needle valve if you fit it the wrong way round! :X

Anyway with new needle valves and correctly fitted gaskets (ahem!), hopefully I'll be up and running again before the weekend's out.....

Bob.

[Guest]

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Got my car running, all i needed to do was adjust the float levels, hardly any fuel in the lh float, doh!

stan

[aerosilver]

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Good stuff. Mine's also running OK againnow after (correctly)fitting the new needle valves and gaskets!

All we need now is the weather.............

Bob.