Paul Hill Posted May 23, 2019 Report Share Posted May 23, 2019 Went out and filled the car up got back home, decided to open the bonnet and to my horror could see fuel weeping from the joint on the metering unit to the dizzy it is a new part 5 months old just wondered how this just occurred out of the blue, is it possible it worked loose Quote Link to post Share on other sites
Waldi Posted May 24, 2019 Report Share Posted May 24, 2019 Hi Paul, it is probably me, but what joint is leaking? Thanks, Waldi Quote Link to post Share on other sites
Paul Hill Posted May 24, 2019 Author Report Share Posted May 24, 2019 Hi Waldi its the joint where Meter unit flange meets the Dizzy. That part should not contain fuel as it’s where the drive shaft dog is, the only thing I can think is there a seal gone inside allowing fuel through Quote Link to post Share on other sites
DaveN Posted May 24, 2019 Report Share Posted May 24, 2019 There is fuel in there but not much check the cavity spill return line connector. Also check that the return line is not blocked. Disconnect and blow down it. It takes a little effort as it’s only a small bore pipe. One other thing to check is the condition of the small section of rubber hose accessible with the near side rear wheel off. dave had the same issue with the push on hose at the MU, the end had collapsed! Quote Link to post Share on other sites
Waldi Posted May 24, 2019 Report Share Posted May 24, 2019 Hi Paul, To add to Dave’s post above: There are 2 seals in the pedestral, one is keeping engine oil where it should, the other is keeping the fuel in the MU. And in-between these 2 oil seals is a tell-tale hole, which gives an early warning should there be leakage of either fluids. The fuel pressure in the MU is high (100-105 PSI, but the pressure at the seal area’s is normally much lower (oil seals cannot handle 100 psi). If you have leakage between MU flange and pedestral, this has little to do with these 2 seals; in fact, the seal on the MU side is doing well as long as no fuel is coming from the tell- tale hole. Between the MU and the pedestal is a thin O-ring, and this is apparently leaking. But why? A blocked return line is a possible cause for that, this will raise the pressure at this (normally) low pressure area. I would first check the MU return line (blow it clear, both sides disconnected), and also replace the leaking O-ring. Make sure it is Viton, not normal NBR rubber. Waldi Quote Link to post Share on other sites
Paul Hill Posted May 24, 2019 Author Report Share Posted May 24, 2019 Thanks Dave and Waldi after taking it apart it’s the O ring going to check the return pipe also Quote Link to post Share on other sites
Paul Hill Posted May 25, 2019 Author Report Share Posted May 25, 2019 Fitted a bit beefy O ring all is well Quote Link to post Share on other sites
bobmac Posted July 25, 2019 Report Share Posted July 25, 2019 Same problem fuel pouring from flange between dizzy and MU , has any one detailed drawing where o rings sit and who supplies? Quote Link to post Share on other sites
Paul Hill Posted July 25, 2019 Author Report Share Posted July 25, 2019 Make sure it’s a Viton rubber O ring Quote Link to post Share on other sites
Mike C Posted July 25, 2019 Report Share Posted July 25, 2019 7 hours ago, Paul Hill said: Make sure it’s a Viton rubber O ring I'd just take the old o rings to my local industrial bearing supplier and ask for replacements in Viton. Generally if they're not in stock I get them next day- but I know they're Viton. If your problem turns out to be a fuelling diaphragm you should be aware that there are some replacements floating around that are made from nitrile not Viton , one I sourced from the UK lasted about an hour on Australian high octane. Quote Link to post Share on other sites
Waldi Posted July 26, 2019 Report Share Posted July 26, 2019 Hi Bob, welcome to this forum. The thick brown work shop manual describes this clearly and also how to replace the seals. A special tool is recommended to protect the seals when inserting the little gear/shaft. The shaft has a sharp end which can damage the seal. If you do not have this book, I recommend you get one, they are around 50 pound. Waldi Quote Link to post Share on other sites
Mike C Posted July 26, 2019 Report Share Posted July 26, 2019 I have a paper copy of the Brown Book- which to me is priceless as it has over 20 years of my handwritten notes scribbled on it as I undertook works on the car. Or, if you want, there are plenty of free pdf sources of the BB on line, like Vitessesteve: https://www.box.com/s/3458383708b0fb05d75f Vitessesteve's website has a lot of other stuff on Triumph cars and Lucas equipment. Quote Link to post Share on other sites
bobmac Posted July 26, 2019 Report Share Posted July 26, 2019 Thanks for replies, took her off road and mothballed after rebuild in October 1989, determined this year to get her up and running and hopefully out on road next year . After almost a years work last Saturday became a milestone in firing her up, after a few problems with fuel pump and nrv, no different to when she was last on road, she started and sounded perfect with 85psi oil pressure marvellous feeling! Second start up was when fuel started leaking from MU, checked spill back line and blocked, renewed rubber hose sections and clear, it may be due to blockage pressure has only blown O ring. Quote Link to post Share on other sites
Waldi Posted July 26, 2019 Report Share Posted July 26, 2019 Hi Bob, That must have been an exciting moment, some 30 years later:) When you have the MU off for replacement of the lip seals in the pedestal, I recommend to have this overhauled as well. There are several O-rings and the diaphragm in there which are very likely not viton, and now over 3 decades old. If age does not let them fail, modern fuels will. Many on here use Neil Ferguson for revision, and this is what I did. If you search other posts on this forum you find loads of information. Neil also reconditioned my injectors, plastic hoses and PRV. One thing less to worry about. Fuel leakages are a safety concern too, especially at the high pressure the PI operates. Best regards, Waldi Quote Link to post Share on other sites
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