PaulT Posted September 1 Report Share Posted September 1 (edited) Hi, Does anyone know what might be causing this issue? Whilst the engine is running there is no leak, however after a couple of minutes of the ignition being turned off fuel starts dripping from the spraying bridge, speed of this varies from incident to incident, can be a slow drip but also been quite quick. Pulling the fuel pipe from the carb, letting the overflow run out and re-attaching the fuel pipe and the leak stops. But starts again after the engine has been started and stopped as described above. Have checked the float, float lever, and needle valve, all appear good, although there is some wear of the brass on the underneath of the float lever. Cleaned out a couple of rubber slivers from the needle valve as well. The washer on the needle valve is not fibre as the workshop manual describes but is metal. Also, cannot see there is a ball under the accelerator pump jet, otherwise everything else looks OK, needle valve moves up and down fine, at least it does when the carb is apart. Any help greatly appreciated Edited September 1 by PaulT Spelling Link to comment Share on other sites More sharing options...
Pete Lewis Posted September 1 Report Share Posted September 1 you do need the non return ball under the accelerator spray nozzle many carbs like these do what we used to call perculating down to heat and fuel levels its why most downdraft have a manifold drain tube its also worth checking yours is clear Pete Link to comment Share on other sites More sharing options...
johny Posted September 1 Report Share Posted September 1 Yes as Pete says level in the float chamber could affect this and I wonder if the metal washer you have under the needle valve is thinner than the usual fibre washer so making the level higher and more prone to percolating.... Link to comment Share on other sites More sharing options...
PaulT Posted September 1 Author Report Share Posted September 1 23 minutes ago, Pete Lewis said: you do need the non return ball under the accelerator spray nozzle many carbs like these do what we used to call perculating down to heat and fuel levels its why most downdraft have a manifold drain tube its also worth checking yours is clear Pete Thank you, I'll get a ball to go in, but do you think this is causing the leaking or will the ball prevent some other issue? Link to comment Share on other sites More sharing options...
PaulT Posted September 1 Author Report Share Posted September 1 5 minutes ago, johny said: Yes as Pete says level in the float chamber could affect this and I wonder if the metal washer you have under the needle valve is thinner than the usual fibre washer so making the level higher and more prone to percolating.... Thank you, I wondered this too, will be trying a thicker washer to see if any impact. Link to comment Share on other sites More sharing options...
johny Posted September 1 Report Share Posted September 1 Out of interest on those carbs where does the float chamber vent to in the event of an overflow due a leaky needle valve? Strombergs have a hole at the front so the excess fuel is pushed out into the filter box but I cant see anything similar on Solex.... Link to comment Share on other sites More sharing options...
Pete Lewis Posted September 2 Report Share Posted September 2 there is normally a vent in the top float cover casting just open to atmosphere . the ball is a non return valve for the accel. pump it will work better with it ,as without you wont get the squirt needs to blank out flat spots Pete Link to comment Share on other sites More sharing options...
PaulT Posted September 2 Author Report Share Posted September 2 1 hour ago, Pete Lewis said: there is normally a vent in the top float cover casting just open to atmosphere . the ball is a non return valve for the accel. pump it will work better with it ,as without you wont get the squirt needs to blank out flat spots Pete Thanks again Pete. I've seen this query about the ball come up several times in my searching for an answer to my query but never what impact there is if it's missing. I've ordered a 1/8 ball, well 72 as they don't come in singles from ebay! Link to comment Share on other sites More sharing options...
PaulT Posted September 18 Author Report Share Posted September 18 Update: The leak appears to have stopped. Not sure which of the following did it, and I still think it may came back: 1. Added the ball under the accelerator pump jet (55) 2. Turned the pump chamber non return valve the correct way as was upside down (58) 3. Added an additional washer under the needle valve (64) Also found the pump diaphragm (46) was inserted the wrong way round. Now, I'm still not getting fuel out of the accelerator pump jet. The diaphragm looks OK but there was no ball bearing (45), does anyone know the size of that? Is it the same as (55)? Link to comment Share on other sites More sharing options...
Pete Lewis Posted September 18 Report Share Posted September 18 sorry cant find the real reference but if you can measure the bore(with a drill or similar) i would hazard a guess its the same part as the acc pump swan neck ball who on earth rebuilt(use that word very loosely ) to refit half the parts upside down or inside out Pete Link to comment Share on other sites More sharing options...
PaulT Posted September 18 Author Report Share Posted September 18 (edited) I know, this is the first time I've ever looked at this stuff so learning as I go. Just adding these pics as they show the hole where the ball (18 in below pic, 45 from previous post) behind the diaphragm goes, it's not clear in the other picture, just in case it's of use to someone else. Edited September 18 by PaulT Spelling Link to comment Share on other sites More sharing options...
johny Posted September 18 Report Share Posted September 18 Certainly the ball 18 looks as if its quite a bit bigger than the swan neck one which follows as you want fuel to flow in to the pump chamber easily but come out with a bit of pressure to give a good squirt... Link to comment Share on other sites More sharing options...
Pete Lewis Posted September 19 Report Share Posted September 19 i would guess any small ball that fits in will act as a non return valve it wont pump with it missing, its probably missing as the previous incumbent couldnt fit it upside down Ha ! you have inherited a bit of a mess Pete Link to comment Share on other sites More sharing options...
PaulT Posted September 19 Author Report Share Posted September 19 I was wondering how the ball would stay in place, if I'm reading this correctly it looks like the ball fits through the hole and then drops down a little so it sits below the lip to hold it in place. Link to comment Share on other sites More sharing options...
johny Posted September 19 Report Share Posted September 19 Yes that looks like it and then keep the carb the right way up until its installed👍 Link to comment Share on other sites More sharing options...
Pete Lewis Posted September 20 Report Share Posted September 20 after all this you should get a far better throttle response and no flat spots Pete Link to comment Share on other sites More sharing options...
PaulT Posted October 6 Author Report Share Posted October 6 (edited) Update: Accelerator Jet is now working. The issue was the inlet from the float chamber to the pump was blocked so the pump was always empty. Compressed air and carb cleaner has cleared it for now. Not sure if the actual blockage came out or just shifted so it could still happen again. If it's any use to anyone the attached pic shows: Orange circle - Inlet from Float Chamber Yellow circle : outlet back to float chamber, for pressure relief (parts 39/40 on the attached diagram) Green circle: Outlet to Accelerator Jet As to the non return valve ball behind the pump diaphragm , I contacted Burlen and the Carb hospital and neither where aware of there being a ball in there despite it showing in several diagrams. However, also attached, Canley Classics have a picture showing the pump without the ball. I can say that the hole this ball would go in, if it ever existed, is much smaller than the 1/8 at the jet end but currently I've not put one in and it's working fine so looks like it's not actually required, at least on mine. And last update for now, the leak came back, currently changed the metal washers under the pin valve to fibre and this is undergoing monitoring! Edited October 6 by PaulT Link to comment Share on other sites More sharing options...
PaulT Posted October 18 Author Report Share Posted October 18 (edited) Final update, the fibre washer appears to have done the trick and stopped the leak, seems so simple now! Edited October 18 by PaulT Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 19 Report Share Posted October 19 That's the needle valve, 51? Mine still leaks from the fuel inlet but I suspect it's down to the wrong connector being supplied in currently-available kits. I've found two different shapes and the shorter stubbier one seems a much better seal against the olive, whilst the newer one has an extension to the end that doesn't quite match what I can see of the very end of the carb inlet profile so will now replace the modern versions with old but seemingly better connectors. Link to comment Share on other sites More sharing options...
PaulT Posted October 19 Author Report Share Posted October 19 (edited) Mine was leaking from the what I believe is called the spray bar running across the throat. The fuel was leaking past the metal washer on the pin valve and finding its way there. I have what looks like PTFE tape around the thread of the connector you've shown put there by a PO, but as it's not leaking I am leaving well alone. Edited October 19 by PaulT Link to comment Share on other sites More sharing options...
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