willcolumbine Posted September 18, 2008 Share Posted September 18, 2008 Alright I give up! I've been getting fuel leaking from my carbs ever since I fitted a new 'repro' fuel pump. I've tried fitting a regulator but no matter what combination of adjusting the pressure on the regulator, messing around with new needle valves, floats, cleaning carbs and fitting new fuel filters I do it just wont stop overflowing out of the damn float chamber!Anyone know anywhere I could get a NOS pump from? Link to comment Share on other sites More sharing options...
PaulB Posted September 18, 2008 Share Posted September 18, 2008 I've heard that alot of the new fuel pumps don't give the right pressure.I was told that TR7 fuel pumps give the right pressure and had one fitted to my spit. Pipes come out at different angles but as long as you don't mind that. Link to comment Share on other sites More sharing options...
willcolumbine Posted September 19, 2008 Author Share Posted September 19, 2008 Nice suggestion! I'd not heard that you could use the TR7 pump.You're not kidding that some new pumps give the wrong pressure. I think it's because they're really designed for something else and all the makers do is change the baseplate. Judging by the amount of fuel it pumps and the fact that the mountings are very similar I wouldn't be suprised if it originated from a big block chevy! Link to comment Share on other sites More sharing options...
cook1e Posted September 19, 2008 Share Posted September 19, 2008 willcolumbine wrote:Alright I give up! I've been getting fuel leaking from my carbs ever since I fitted a new 'repro' fuel pump. I've tried fitting a regulator but no matter what combination of adjusting the pressure on the regulator, messing around with new needle valves, floats, cleaning carbs and fitting new fuel filters I do it just wont stop overflowing out of the damn float chamber!Anyone know anywhere I could get a NOS pump from?I take it you have replaced the needle valves in the top of the float chambers and that the floats are not punctured and fitted at the correct hieight. In my experience fuel leaks in SU cards are quite often due to problems with the needle valves or floats.The best needle valves IMHO ar ethe after market ones with the rubber tips, they seal better than the original ones. Link to comment Share on other sites More sharing options...
willcolumbine Posted September 19, 2008 Author Share Posted September 19, 2008 Yeah, I replaced the needle valves with the standard type (with rubber tips) and then tried the ball type ones that the mini crowd go for. The floats were good too - I tested them by holding them underwater overnight and they didn't let any water in. I've not adjusted the float height though. I dont think thats possible on later SU's like mine. Link to comment Share on other sites More sharing options...
DaveKent Posted September 20, 2008 Share Posted September 20, 2008 i gave up with buying new needle valves, they all seem to be rubbish. in the end i used some second hand ones from a pair of mini carbs that i had and no problems ever since!! Link to comment Share on other sites More sharing options...
Tim Bancroft Posted September 20, 2008 Share Posted September 20, 2008 Is'nt the problem with these new pumps that a spacer has to be present if a long arm fuel pump? Could gaskets used to space the pump to obtain the right pressure? Link to comment Share on other sites More sharing options...
Deleted User Posted September 20, 2008 Share Posted September 20, 2008 I dont think the pump arm has anything to do with the fuel pressure.I believe that the pressure is "controlled" by the spring under the diaphram inside the pump (item 12 in the picture)All that you will achieve by fitting extra gaskets is to reduce the maximum rate at which fuel can be pumped, so at maximum fuel demand you might empty the float chambers faster than the pump can supply fuel. Link to comment Share on other sites More sharing options...
THe Maestro Posted September 20, 2008 Share Posted September 20, 2008 when you put the carb back together did you line up the diaphram in the correct place? There is a mark on it at some point round the edge that you have to line up with a certain part of the enclosure. If you don't petrol will flood out of the drain plug. Link to comment Share on other sites More sharing options...
willcolumbine Posted September 21, 2008 Author Share Posted September 21, 2008 I've got SU's so I don't think a diaphram could be the problem! Wierdly enough it seems to have stopped doing it for the minute. Maybe I've finally got the regulator set just right! I'm still not happy about the set up though. I'd like to loose the regulator if possible and if the TR7 pump's going to work then that seems like the best answer. Link to comment Share on other sites More sharing options...
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