Adam Windsor Posted June 20, 2020 Report Share Posted June 20, 2020 Can you help advise how I fix a fuel leak from the base of the Lucas control unit attached to the metering unit please? thank you adam Quote Link to post Share on other sites
HSM Posted June 20, 2020 Report Share Posted June 20, 2020 Usual cause is a perforated fuel diaphragm seal , readily available from usual suppliers. Requires removing metering unit to replace & may require datum track re-setting. Harvey S. Maitland Quote Link to post Share on other sites
Adam Windsor Posted June 20, 2020 Author Report Share Posted June 20, 2020 46 minutes ago, HSM said: Usual cause is a perforated fuel diaphragm seal , readily available from usual suppliers. Requires removing metering unit to replace & may require datum track re-setting. Harvey S. Maitland Thanks Harvey - will take a look and check it out. Quote Link to post Share on other sites
John L Posted June 20, 2020 Report Share Posted June 20, 2020 There is leak hole in the pedestal, you don't say exactly where its coming from. items here 116 or 103 here https://www.moss-europe.co.uk/shop-by-model/triumph/tr5-6/engine/engines-components/internal-engine-tr5-6-1967-76.html John Quote Link to post Share on other sites
Adam Windsor Posted June 20, 2020 Author Report Share Posted June 20, 2020 1 hour ago, John L said: There is leak hole in the pedestal, you don't say exactly where its coming from. items here 116 or 103 here https://www.moss-europe.co.uk/shop-by-model/triumph/tr5-6/engine/engines-components/internal-engine-tr5-6-1967-76.html John Thanks John. The leak is coming from the bottom of the control unit as far as I can work out. adam Quote Link to post Share on other sites
astontr6 Posted June 20, 2020 Report Share Posted June 20, 2020 4 hours ago, Adam Windsor said: Can you help advise how I fix a fuel leak from the base of the Lucas control unit attached to the metering unit please? thank you adam Hi Adam, How old is your M/U? as the seals in there may be not ethanol proof and in my view if it is over 5 to 10 years old its is uneconomic just to replace the 2 seals required as you have not replaced all the others. Best to buy an exchange unit that has all the correct seals for the current levels of ethanol? Bruce. Quote Link to post Share on other sites
Adam Windsor Posted June 20, 2020 Author Report Share Posted June 20, 2020 54 minutes ago, astontr6 said: Hi Adam, How old is your M/U? as the seals in there may be not ethanol proof and in my view if it is over 5 to 10 years old its is uneconomic just to replace the 2 seals required as you have not replaced all the others. Best to buy an exchange unit that has all the correct seals for the current levels of ethanol? Bruce. Thanks Bruce - it’s almost certainly 8-10 years old . Are exchange units expensive do you know? Adam Quote Link to post Share on other sites
astontr6 Posted June 20, 2020 Report Share Posted June 20, 2020 22 minutes ago, Adam Windsor said: Thanks Bruce - it’s almost certainly 8-10 years old . Are exchange units expensive do you know? Adam I think the current price is around £250! Is your engine modified i.e. modified head, cam & exhaust manifold-exhaust system? If it is you may need a KMI Sprint M/U? Bruce. Quote Link to post Share on other sites
Waldi Posted June 20, 2020 Report Share Posted June 20, 2020 I would sent it to Neil Ferguson, together with the prv, nylon lines and injectors for service and calibration. He can supply the O-rings for the connections from the lines to the MU too. I’m not easily impressed but now I was! Waldi Quote Link to post Share on other sites
Mike C Posted June 20, 2020 Report Share Posted June 20, 2020 If you buy another fueling diaphragm make sure it is made from Viton. I purchased one from the brothers and it lasted less than an hour on Australian high octane. The problem with non Viton diaphragms is that the elastomer expands and you lose the tight fit needed to seal against the shaft. Quote Link to post Share on other sites
Adam Windsor Posted June 21, 2020 Author Report Share Posted June 21, 2020 12 hours ago, astontr6 said: I think the current price is around £250! Is your engine modified i.e. modified head, cam & exhaust manifold-exhaust system? If it is you may need a KMI Sprint M/U? Bruce. Eek! It’s not modified in anyway thankfully- thanks Adam Quote Link to post Share on other sites
Adam Windsor Posted June 21, 2020 Author Report Share Posted June 21, 2020 11 hours ago, Waldi said: I would sent it to Neil Ferguson, together with the prv, nylon lines and injectors for service and calibration. He can supply the O-rings for the connections from the lines to the MU too. I’m not easily impressed but now I was! Waldi Thanks Waldi - do you have contact details for Neil F please! Quote Link to post Share on other sites
Adam Windsor Posted June 21, 2020 Author Report Share Posted June 21, 2020 9 hours ago, Mike C said: If you buy another fueling diaphragm make sure it is made from Viton. I purchased one from the brothers and it lasted less than an hour on Australian high octane. The problem with non Viton diaphragms is that the elastomer expands and you lose the tight fit needed to seal against the shaft. Thanks Mike - I will! Quote Link to post Share on other sites
ntc Posted June 21, 2020 Report Share Posted June 21, 2020 I would check the return pipe is clear Quote Link to post Share on other sites
Spit_2.5PI Posted June 21, 2020 Report Share Posted June 21, 2020 12 hours ago, astontr6 said: you may need a KMI Sprint M/U? I've never heard of that Bruce. Does he just calibrate for increased fuelling or are there any modifications do you know? Cheers, Richard Quote Link to post Share on other sites
astontr6 Posted June 21, 2020 Report Share Posted June 21, 2020 1 hour ago, Spit_2.5PI said: I've never heard of that Bruce. Does he just calibrate for increased fuelling or are there any modifications do you know? Cheers, Richard Hi Richard, This has always been the case. KMI years ago were the originators of the Bosch Pump conversion, some of the staff had worked for Lucas- CAV, including the original owner who has now retired. They also re-con all types of Bosch Injection. They also worked very closely with SAH who were the top Triumph tuners of the 1970's and this is where the Sprint M/U originated from, along with SAH's 357 cam which used this mod and other cam's of there's As I understand the Sprint M/U is a re-calibrated to suit what cam you have fitted. I don't believe that the fuel metering cam is changed? But there are some cams that require that mod. I have a Newman PH2 cam, very similar to a 357 which required a Sprint M/U as I have other SAH mod's. Bruce. Quote Link to post Share on other sites
Waldi Posted June 21, 2020 Report Share Posted June 21, 2020 I do have Neils phone number, have sent to a PM. Waldi Quote Link to post Share on other sites
ntc Posted June 21, 2020 Report Share Posted June 21, 2020 Before you send it to Neil as I posted check the return line also where it connects to the mu is it push in or screwed in as they can weep from there. Quote Link to post Share on other sites
Spit_2.5PI Posted June 22, 2020 Report Share Posted June 22, 2020 Thanks Bruce. My engine builder got the M/U from KMI. I remember him saying he described the build (higher compression, mildly modified head, etc.) and KMI adjusted the fuelling accordingly. It all sounded a bit hit & miss to me, but now I see they're obviously experienced in such things! Cheers, Richard Quote Link to post Share on other sites
Adam Windsor Posted June 22, 2020 Author Report Share Posted June 22, 2020 On 6/20/2020 at 4:44 PM, HSM said: Usual cause is a perforated fuel diaphragm seal , readily available from usual suppliers. Requires removing metering unit to replace & may require datum track re-setting. Harvey S. Maitland Thanks Harvey - pretty certain the diaphragm has failed as there’s plenty of fuel coming out of the control unit housing. Is it possible to replace this without removing the unit? Adam Quote Link to post Share on other sites
Mike C Posted June 22, 2020 Report Share Posted June 22, 2020 I couldn't find a way. The MU components need to be carefully reassembled and the screws that hold down the diaphragm evenly torqued. For me it was a bench job. Quote Link to post Share on other sites
HSM Posted June 23, 2020 Report Share Posted June 23, 2020 You can remove the metering unit with distributor whilst still leaving the injectors in the throttle bodies ( it is a bit fiddly ) undo the 4 screws to remove the control unit to access the diaphragm for removal ( the centres require pressing into the new diaphragm ). Take care to set ignition & fuel timing as in the instruction manual when reassembling. Harvey S. Maitland Quote Link to post Share on other sites
Adam Windsor Posted June 23, 2020 Author Report Share Posted June 23, 2020 1 hour ago, HSM said: You can remove the metering unit with distributor whilst still leaving the injectors in the throttle bodies ( it is a bit fiddly ) undo the 4 screws to remove the control unit to access the diaphragm for removal ( the centres require pressing into the new diaphragm ). Take care to set ignition & fuel timing as in the instruction manual when reassembling. Harvey S. Maitland Thanks Harvey - in the manual it advises to turn the engine over so that pistons 1 & 6 are at TDC with number 1 firing. Do you know how I set this up correctly before removing the MU? Adam Quote Link to post Share on other sites
Adam Windsor Posted June 23, 2020 Author Report Share Posted June 23, 2020 This is the culprit! A small tear in the diaphragm as correctly diagnosed by most of you ! Let’s hope I can put it all back together again when the new part arrives! Thanks Quote Link to post Share on other sites
BlueTR3A-5EKT Posted June 23, 2020 Report Share Posted June 23, 2020 (edited) Any hints or help on checking the MU reassembly here? https://www.lucasinjection.com/Lucas Mk2 manual page 22 and 23.htm or here http://vitessesteve.co.uk/LucasStuff/Lucas_Petrol_Injection_Manuals and for the visual approach Cheers Peter W Edited June 23, 2020 by BlueTR3A-5EKT Quote Link to post Share on other sites
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