philbey Posted May 26, 2009 Report Share Posted May 26, 2009 A non-return circuit should see more pressure than a return circuit, as the pump is constantly pushing against the needle. The difference with the Jay's setup is that he had a Weber, which might not handle the same pressure at the needle than a factory item. I would say you have no problems. Try it and see, if you think you are getting too much pressure, put a regulator in it. Quote Link to comment Share on other sites More sharing options...
Falken_KE30 Posted May 26, 2009 Author Report Share Posted May 26, 2009 well both pumps look the same.... surely i can just put the KE55 top that has no return line on it, on the KE70 bottom half? Quote Link to comment Share on other sites More sharing options...
philbey Posted May 26, 2009 Report Share Posted May 26, 2009 Yep, should be fine. Quote Link to comment Share on other sites More sharing options...
CALE12 Posted May 26, 2009 Report Share Posted May 26, 2009 Yep, should be fine.i have mine blocked off..but if your fuel tank has a AIR TIGHT seal the pressure build up will push fuel through the carbie and down into the engine oil .....just went through that ! it took me a month and x3 fuel pumps x2 carbie kits to work that out..... just a thought Quote Link to comment Share on other sites More sharing options...
Falken_KE30 Posted May 26, 2009 Author Report Share Posted May 26, 2009 yeah i reckon ill switch tops, i never had a problem with that carby before. ill let ya's know when its all running again, get the new carby on friday.. so full steam ahead on weekend Quote Link to comment Share on other sites More sharing options...
philbey Posted May 27, 2009 Report Share Posted May 27, 2009 You shouldn't have an airtight tank anyway, that's what the breather is all about. Interesting point though..... That's quite a bit of air pressure! Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted May 27, 2009 Report Share Posted May 27, 2009 Yeah, put up a post about that whole episode cale... That sounds like something that could drive any of us nuts trying to fix! Return lines are nice because otherwise the pump diaphram is working against a high pressure and can't pump the fuel anywhere. Stresses the flexible diaphram, but in saying so most old cars never ran them and the pumps survived OK. Quote Link to comment Share on other sites More sharing options...
Falken_KE30 Posted May 27, 2009 Author Report Share Posted May 27, 2009 well the bottom halfs on both pumps are same the chambers inside the top halfs are different. seems the one without the return line has a bigger chamber to accommodate more fuel and less pressure at a guess. Quote Link to comment Share on other sites More sharing options...
Felix Posted May 27, 2009 Report Share Posted May 27, 2009 The fuel pressure in a mechanical pump is set by the diaphragm spring. Once the set pressure is reached the pump sorta freewheels. Try it, block off the outlets and operate the lever, after a couple of pumps the resistance on the lever reduces. Quote Link to comment Share on other sites More sharing options...
Falken_KE30 Posted May 27, 2009 Author Report Share Posted May 27, 2009 well I'm going to use the KE55 top half on a KE70 bottom half to be safe. Thanks for all the help guys Quote Link to comment Share on other sites More sharing options...
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