J.C. Posted August 21, 2023 Report Share Posted August 21, 2023 Have got a TR6 that is running really well. It starts from cold with no issue and is a pleasure to drive, but once I have got it running if I then pull over and stop for about 5 to 10 minutes, when I start it up it runs very 'lumpy' for a couple of minutes (not firing on all cylinders) but eventually clears and runs just as well as before. The annoying thing is this does not happen every time, probably one in three. Was thinking that maybe the hot air and oil mix that comes from the rocker cover, through the breather pipe and into the air manifold might be providing 'dirty air' creating this situation. Am thinking of taking the breather pipe off and applying a small air filter to each end (rocker cover and air manifold) to see if this sorts the issue out. What are peoples thoughts and would this constitute a 'modification' in the eyes of an insurance company. Any advice gratefully received. John C Quote Link to post Share on other sites
harlequin Posted August 21, 2023 Report Share Posted August 21, 2023 I can't see the breather making any difference to starting, if it did Triumph would not have fitted it. Have you checked the air filter is clean and the choke lever on the MU is fully home when the choke is disengaged? George Quote Link to post Share on other sites
J.C. Posted August 21, 2023 Author Report Share Posted August 21, 2023 Hello George. The air filter is new and the choke lever on the MU is fully home when choke disengaged. The MU was refurbished and calibrated less the 1k miles ago. Quote Link to post Share on other sites
John L Posted August 21, 2023 Report Share Posted August 21, 2023 You might need to get a second person here to help with the diagnostic. Get them to start the engine, and you feel which of the injector pipes is not pulsing, that should lead you to the injector or the delivery valve as the problem perhaps. Keep us informed as what you find pls. John Quote Link to post Share on other sites
peejay4A Posted August 21, 2023 Report Share Posted August 21, 2023 Do you have braided injector pipes? Some of them can allow fuel vaporisation with a hot engine on restart. Quote Link to post Share on other sites
Mike C Posted August 21, 2023 Report Share Posted August 21, 2023 Does this only happen after a long run on a hot day? If so it could be hot fuel in the tank vapourizing in the pump suction. I'd be surprised if the cause was anything to do with the rocker cover vent system. Quote Link to post Share on other sites
elclem1 Posted August 22, 2023 Report Share Posted August 22, 2023 one or two of the NRV in the MU may be passing back causing an air lock in the injector pipes? Quote Link to post Share on other sites
astontr6 Posted August 22, 2023 Report Share Posted August 22, 2023 15 hours ago, J.C. said: Have got a TR6 that is running really well. It starts from cold with no issue and is a pleasure to drive, but once I have got it running if I then pull over and stop for about 5 to 10 minutes, when I start it up it runs very 'lumpy' for a couple of minutes (not firing on all cylinders) but eventually clears and runs just as well as before. The annoying thing is this does not happen every time, probably one in three. Was thinking that maybe the hot air and oil mix that comes from the rocker cover, through the breather pipe and into the air manifold might be providing 'dirty air' creating this situation. Am thinking of taking the breather pipe off and applying a small air filter to each end (rocker cover and air manifold) to see if this sorts the issue out. What are peoples thoughts and would this constitute a 'modification' in the eyes of an insurance company. Any advice gratefully received. John C I suspect that your injector pipes are draining down due poor seals inside the injectors themselves. I have had this problem in the past and I had to replace them with a high grade Viton from a company called Promax. Bruce. Quote Link to post Share on other sites
Martin50 Posted August 22, 2023 Report Share Posted August 22, 2023 John, do some of your injector pipes touch rocker or hot surface on way to injectors? Just thinking if it starts okay from cold, are you getting vapour block in one or two of the injector pipes when no flow of fuel and if pipe is picking up heat from touching hot surface. Easy one to check / look for. Not sure if vapour lock is feasible but just a thought. Quote Link to post Share on other sites
J.C. Posted August 22, 2023 Author Report Share Posted August 22, 2023 Thank you for all the replies, very much appreciated. The filter on the the rocker cover was a bit of a long shot but will check the injector pipes touching the rocker cover (Martin 50), and check the seals on the injectors (astontr6) as a starting point. Will report back. Quote Link to post Share on other sites
J.C. Posted September 8, 2023 Author Report Share Posted September 8, 2023 Appreciate all the responses from everyone and finally (fingers crossed) seem to have sorted the problem. As the did not happen all the time, just occasionally, it was difficult to identify which cylinder might be the culprit. Eventually managed to identify number one cylinder as the issue, so replaced the injector and seal and so far everything seems fine (famous last words). On a separate note had a look at the injectors on other cylinders and could not get the nylon adaptor that the injector sits in out. Is there a technique to this os is it a case of long nose pliers and hard tug? Also was thinking of trying to refurb the old injector myself but how on earth do you get that small cir clip off the end? Quote Link to post Share on other sites
John L Posted September 8, 2023 Report Share Posted September 8, 2023 If you want to take that circlip off, its a good idea to do it in a bag, as they will fly off, and you will never find it, and its not possible to get replacements!!! There is a technic to get it off, I think I have used a pointed spike to pry it off, but was a long time ago now. John Quote Link to post Share on other sites
Mk2 Chopper Posted September 9, 2023 Report Share Posted September 9, 2023 14 hours ago, John L said: If you want to take that circlip off, its a good idea to do it in a bag, as they will fly off, and you will never find it, and its not possible to get replacements!!! There is a technic to get it off, I think I have used a pointed spike to pry it off, but was a long time ago now. John I've managed to get some circlips off ebay a while ago, for one of my injectors that was missing one. But totally do it in a bag! Gareth Quote Link to post Share on other sites
Mk2 Chopper Posted September 9, 2023 Report Share Posted September 9, 2023 15 hours ago, J.C. said: Appreciate all the responses from everyone and finally (fingers crossed) seem to have sorted the problem. As the did not happen all the time, just occasionally, it was difficult to identify which cylinder might be the culprit. Eventually managed to identify number one cylinder as the issue, so replaced the injector and seal and so far everything seems fine (famous last words). On a separate note had a look at the injectors on other cylinders and could not get the nylon adaptor that the injector sits in out. Is there a technique to this os is it a case of long nose pliers and hard tug? Also was thinking of trying to refurb the old injector myself but how on earth do you get that small cir clip off the end? It's a sprung clip, so hold one end with a flat blade screwdriver, and using a second one force it apart to release from the groove. Gareth Quote Link to post Share on other sites
Steve-B Posted September 9, 2023 Report Share Posted September 9, 2023 (edited) Where does one get new Vitron rings that go outside the white rings holding the injectors and the tiny ones that hold the injectors when inserted into the white rings? I have a couple that are loose. TR Shop? Edited September 9, 2023 by Steve-B Quote Link to post Share on other sites
Mk2 Chopper Posted September 9, 2023 Report Share Posted September 9, 2023 KMI do the large ones, not sure about the small internal ones, but worth an ask. Gareth Quote Link to post Share on other sites
John L Posted September 9, 2023 Report Share Posted September 9, 2023 Chris Witor does the small ones, https://www.chriswitor.com/proddetail.php?prod=CW3354V John Quote Link to post Share on other sites
Steve-B Posted September 9, 2023 Report Share Posted September 9, 2023 (edited) Thanks Gareth and John L. (John C: apologies if I thread hijacked) Edited September 9, 2023 by Steve-B Quote Link to post Share on other sites
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