Colin Fairhurst Posted October 24, 2018 Report Share Posted October 24, 2018 I have recently fitted a new mechanical petrol pump to my TR2 and the carburettors flood over intermittently. I have since replaced the float chamber needle valves with Grose Jets but still get the intermittent flooding. I am thinking that maybe the new pump is producing too high a pressure for the float chamber valves to cope with. Does anyone know what the pressure should be? Regards, Colin Quote Link to post Share on other sites
RobH Posted October 24, 2018 Report Share Posted October 24, 2018 Have you fitted the pump correctly? The pumping is done by the return spring, the cam only lifts the actuating arm which is then returned by the spring. I believe it is possible to get the arm on the wrong side of the cam so that the cam is pushing the arm down rather than lifting it up......... Quote Link to post Share on other sites
Colin Fairhurst Posted October 24, 2018 Author Report Share Posted October 24, 2018 Thanks Rob. I will check that but I was aware of that possibility when I fitted the pump, but it is still worth checking. I was thinking that perhaps the return spring may be too strong. In which case swopping the spring from the old pump ( if that is possible) may solve the problem. It would be useful to know what the pressure should be. Regards, Colin Quote Link to post Share on other sites
RobH Posted October 24, 2018 Report Share Posted October 24, 2018 I believe it should be between 1.5 to 3.5 psi Colin. Quote Link to post Share on other sites
Colin Fairhurst Posted October 26, 2018 Author Report Share Posted October 26, 2018 Hi Rob, I put a pressure gauge on the outlet of the new petrol pump and by operating the lever I got a reading of 5 lbs psi. This afternoon I removed the pump and took the return spring out and did the same with the old pump. Comparing the two springs with each other there was a considerable difference in there strengths so I put the old spring into the new pump and refitted it to the engine . Again by operating the lever I got a reading of 2 lbs psi on the gauge which as you stated is probably the correct pressure. I haven't yet had the opportunity to give the car a run but if that has solved the problem then obviously 5 lb psi is too much for both the needle valves and the grose jets. Regards, Colin Quote Link to post Share on other sites
RobH Posted October 26, 2018 Report Share Posted October 26, 2018 Yes 5 psi is certainly a bit too much for SUs and a quick web search shows several instances of people complaining of the same thing. If it was a new pump perhaps you should let whoever supplied it know about this ? Quote Link to post Share on other sites
Colin Fairhurst Posted October 26, 2018 Author Report Share Posted October 26, 2018 18 minutes ago, RobH said: Yes 5 psi is certainly a bit too much for SUs and a quick web search shows several instances of people complaining of the same thing. If it was a new pump perhaps you should let whoever supplied it know about this ? I will do that. Regards, Colin Quote Link to post Share on other sites
Mick Forey Posted November 1, 2018 Report Share Posted November 1, 2018 You might also consider raising this as a parts quality issue https://www.tr-register.co.uk/pqi I personally think that flooding carburettors is a potential safety issue just like any fuel leak. If there are good and bad pumps out there, the members need to know. Mick Quote Link to post Share on other sites
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