RJWW Posted February 25 Report Share Posted February 25 I have a 1971 150 bhp TR6 which is not used enough😔. With a good clean of the plugs we got it running yesterday and so took it out for a spin, to make sure everything was as it should be. However, in each gear it would not pull above 2500 rpm. Does anyone please have any experience of this issue and is there a simple solution. I ask as the quicker I can get this resolved, then the more the car will be used which has got to be a good thing for both the car and me Thanks in anticipation  Link to comment Share on other sites More sharing options...
JohnD Posted February 25 Report Share Posted February 25 Little used?  Gum in the jets? Carb cleaner spray or a bottle of Redex or similar in the tank? John Link to comment Share on other sites More sharing options...
SpitFire6 Posted February 25 Report Share Posted February 25 Try pulling the choke out/modulating to see if it runs better. Link to comment Share on other sites More sharing options...
johny Posted February 25 Report Share Posted February 25 Hmmm this is a PI model isnt it so a bit more complicated. Does it misfire and hesitate when you get to 2500rpm? I think theres a few possible causes starting with: Gummed up injectors or metering unit. Loss of vacuum to metering unit so it doesnt dispense enough fuel - you could check the vac pipe and its connections for leaks. Link to comment Share on other sites More sharing options...
rlubikey Posted February 25 Report Share Posted February 25 Check the injectors are all working. On tickover, feel the pipes to each injector in turn. You should feel a pulse which should be the same in each pipe. If not, one or more injector pipes may need bleeding to remove any air that's gathered inside. As John says, gummed up injectors will give sub-optimal spray pattern. Be careful about checking this as removing injectors from the manifold one at a time means spaying petrol around a (potentially) hot engine bay. The revs will rise as you remove each injector as you're letting air into the manifold, but will return to normal when replaced. Then you do the next one in sequence. The metering unit works on a vacuum, so if your valve clearances aren't correct this will throw the mixture out of the window. Any manifold leaks, vacuum tube leak, or metering unit diaphragm leak will also upset the mixture as Johny points out. A simple test of the pipe and diaphragm is, with the engine NOT running, disconnect the vacuum tube at the manifold end and suck air out of the end of the tube, then cover the end with your tongue. Does the tube and metering unit hold the vacuum for at least a few seconds? If yes then that's probably not the problem. Pulling the choke out *just a little bit* when you hit the flat spot is a good tip, and will suggest the mixture is weak for one of the above reasons - or something else! That's all I can think of at the moment, except to say that the Lucas PI system is generally reliable, so don't discount the problem lying elsewhere. It could easily be the ignition - i.e. coil, points, leads, plugs, etc. Good luck and let us know how you're getting on. Cheers, Richard Link to comment Share on other sites More sharing options...
JohnD Posted February 25 Report Share Posted February 25 (edited) Richard is quite right about petrol risk! I've made a gandy hadget to test them all at once, a rack with a trough and a flange that has six holes drilled to take the injectors. The trough catches the sprayed fuel and It can be sat in a large tin (Catering Coffee) to catch overflow. See pics. Disconnect the ignition, ensure your battery is well charged and move all the injectors to the rack.  Turn the engine on the starter, until you see fuel flowing - you hope spraying! - from the injectors. In this way comparison of volume and spray pattern becomes very easy! Good luck, John PS. The red stuff isn't blood , it's Haematite sealant in the seams. I smeared it on before pop riveting them together. Edited February 25 by JohnD 1 Link to comment Share on other sites More sharing options...
RJWW Posted February 25 Author Report Share Posted February 25 thanks all - such a wet day it didn't make it out of the garage and now work will get in the way Will try probably in a fortnight and will definitely let you know how it works out. The PI system was problematic when first bought the car , but when sorted has needed little if any tinkering in 20 plus yrs Link to comment Share on other sites More sharing options...
rlubikey Posted February 26 Report Share Posted February 26 16 hours ago, RJWW said: but when sorted has needed little if any tinkering in 20 plus yrs It will almost certainly have pre-ethanol seals and o-rings. My money's on degraded butyl rubber due to ethanol in modern petrol. Link to comment Share on other sites More sharing options...
RJWW Posted March 11 Author Report Share Posted March 11 Thanks All. Had a good day with the car on Saturday: - felt an even pulse on each fuel pipe, - choke didn't really make any difference, - plugs all cleaned ( electronic ignition) - got the car idling nicely - added wynn's injector cleaner and off we went. After 30 minutes without using the overdrive, keeping the rev's up, and you could feel the car stretching itself out and the performance improving. By the end of the run I had to keep reminding myself that this is a 52 yr old car out for the first time in a while.  A lesson learnt - it needs to be used. Thanks for all the suggestions which will be stored just in case!      2 Link to comment Share on other sites More sharing options...
Unkel Kunkel Posted March 11 Report Share Posted March 11 On 25/02/2024 at 16:35, JohnD said: a gandy hadget like that Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 11 Report Share Posted March 11 Gandy hadjets and Italian tune ups all come in very handy at times of frustration . Pete Link to comment Share on other sites More sharing options...
johny Posted March 11 Report Share Posted March 11 6 hours ago, RJWW said: A lesson learnt - it needs to be used. Thanks for all the suggestions which will be stored just in case! No excuses now the sunshine is on its way🤔 Link to comment Share on other sites More sharing options...
RJWW Posted March 16 Author Report Share Posted March 16 Based on today, sunshine is not required for this car to continue to make me smile 🙂. Now there is a Spitfire to get out there! 1 Link to comment Share on other sites More sharing options...
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