venturi booster overfueling / irratic idle

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bennpari
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Posts: 2
Joined: Fri Sep 02, 2022 6:56 pm
Drives: 86c
Location: East sussex

venturi booster overfueling / irratic idle

Post by bennpari »

Hi all. Recently bought myself a little 1043cc mk 2 breadvan as a little run about and I'm totally stupmed by it. It turned up as a non runner and I have been fixing all the niggling issues you get from a 32 year old car. Pretty much there now except I can't get the carb to idle at 900rpm. It's currently idling between 1150-1350rpm and goes up and down through that range. It basically had every vac leak going so have replaced all vac pipes, mounting flange and tested for leaks ( all good) . I was getting no ignition live to the cut off solenoid circuit, fixed that and it's working now. Rebuilt the carb and set it to its base settings, new gaskets, needle Valve etc. New tank , fuel lines , swirl pot and filters. On starting it up and looking down the carb venturi I can see fuel constantly dripping down the throat from the booster venturi. I thought that either the float was stuck or faulty needle Valve was at fault but after taking it apart and testing it and adjusting the float heights to various different heights umpteen times its still bloody doing it. Next thought was that the fuel pressure was too high for the weber tla1 carb. Tested the fuel pressure and the pump is putting out 6.5psi. That's way higher than I've ever run weber carbs at so I nabbed a fuel regulator off my campervan and tested it again with the fuel pressure at 2-3.5psi and it makes no difference. I'm at a complete loss now. I hate not being able to fix things . I cant stop thinking about it till I do and it's driving me nuts. Can anyone think k of anything I haven't tried already? Cheers
bennpari
New
Posts: 2
Joined: Fri Sep 02, 2022 6:56 pm
Drives: 86c
Location: East sussex

Re: venturi booster overfueling / irratic idle

Post by bennpari »

For anyone still using this forum and having the same issue as I did I managed to fix it. The fuel pump is putting out 6.5 psi which is too much for the carb. I tested this previously by putting a fuel regulator directly after the swirl pot before it went to the carb and then dialed the pump down but it made no difference. This time round I fitted a fuel regulator directly after the fuel pump before it went to the swirl pot and it fixed the issue. Car now idles perfectly and no carb overfueling. Fuel regulator is set at 2.8 psi
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