hot-growler Posted July 22, 2014 Report Share Posted July 22, 2014 Hi, I've been having a problem with my '72 CP fuel injected TR6. It starts reasonably from cold, after a bit of turning over and after 10 mins if I say have nipped into a shop and get back it is ok. the problem is after leaving the car an hour or so, if I start it, it almost catches on first turn of key but doesn't and then I have to turn it over for up to a minute with no joy. The battery gives up first. I put a brand new 80ah battery on it today and it finally, but very reluctantly started. it has got to the stage I don't like driving it for this reason. Any ideas? steve. Quote Link to post Share on other sites
Peter Cobbold Posted July 22, 2014 Report Share Posted July 22, 2014 It could be flooding. In hot weather, and if the engine is hot, dont use the choke - unless if fails to start after a few seconds. There are other possibilities- vapour lock in the injector hoses over a hot engine left to stand. Open the bonnet and let cooler air in. Quote Link to post Share on other sites
hot-growler Posted July 22, 2014 Author Report Share Posted July 22, 2014 are there any more permanent remedies? Quote Link to post Share on other sites
Peter Cobbold Posted July 22, 2014 Report Share Posted July 22, 2014 Try different fuel. The higher RON stuff may be better behaved that supermarket stuff. Not because of RON itself, but because I suspect butane content of cheap fuels is high. But I cant prove it as the oil co recipes are secret, as long as they comply with the BS. Quote Link to post Share on other sites
hot-growler Posted July 22, 2014 Author Report Share Posted July 22, 2014 Hi, just went out to the car and as always not starting. Took injectors out of their holes and there was no fuel at all coming out of them? Does that suggest pressure too low to inject the fuel? I pulled on the injector nozzles and a bit of a fuel came out of each? Am I getting any closer to a cure? Quote Link to post Share on other sites
Rob Salisbury Posted July 22, 2014 Report Share Posted July 22, 2014 From what you say it sounds to me that the PRV is set at the low end of what will work, try raising the pressure slightly(best done with a pressure gauge kit if you can get one) but can just be done incrementally and another trick to starting Pi engines is to turn on the ignition and wait a few seconds as the fuel pressure builds up (you can usually hear the change in the noise from the fuel pump) and then start cranking. When cold pull the choke right out, and then progressively back as soon as the engine will run smoothly, when hot no choke, just hold the throttle down between 1/3 and 1/2 as you crank until the engine catches but do wait for the fuel pressure to build up first. Cheers Rob Quote Link to post Share on other sites
Steves_TR6 Posted July 22, 2014 Report Share Posted July 22, 2014 Hi Steve Obviously there are starting issues associated with the PI system, probably. But you also seem to have an issue with the starter quickly flattening the battery. This is quite common with the original starter, it's an old design and also 40 years old.... So a recon starter or a modern replacement might be a good idea. There are list of threads on here about setting up the PI, or just contact Neil Ferguson who has worked wonders for many at very reasonable cost. Hth Steve Quote Link to post Share on other sites
Phil Kirk Posted July 22, 2014 Report Share Posted July 22, 2014 Hi, Steve have you by any chance have braided injection hoses? If so it could be causing your problem due to the hoses getting hot and causing the fuel to vaporise Cheers Phil Quote Link to post Share on other sites
Peter Cobbold Posted July 22, 2014 Report Share Posted July 22, 2014 (edited) Hi, just went out to the car and as always not starting. Took injectors out of their holes and there was no fuel at all coming out of them? Does that suggest pressure too low to inject the fuel? I pulled on the injector nozzles and a bit of a fuel came out of each? Am I getting any closer to a cure? You did check an injector with the starter turning the engine? An injector should give one squirt per two revolutions, so the engine has to be turning on the starter, not just with the ignition on. !!>> Watch out for fire - direct fuel spray into a bottle, never towards the disy, and have extinguisher to hand.Ideally dont do it in the garage either. If you did the test correctly and there's no spray then there is a PI fault. If the correct test shows fuel sprays then forget checking the PI until you've checked the spark timing. The points can close up remarkably quickly to the point where it wont start. Edited July 22, 2014 by Peter Cobbold Quote Link to post Share on other sites
jamesStag Posted July 22, 2014 Report Share Posted July 22, 2014 Hi Steve, You don't say if you are new to the TR6, but in case you are - in general yes PI can have its foibles, but once setup well it can be very reliable too. You certainly should not have significant hot starting trouble as you've described, so something is wrong. As others have said, I think it could well be that the pump pressure at the PRV is set just a little low. If you haven't got a test pressure gauge and a T-piece to install it on the inlet to the MU, then I highly recommend it. Since I got one I've learnt a lot about the PI and correct pressure (both static running/reving, and also whilst driving under load ) are key. the parts for a test gauge are mentioned on other posts here, should only be around £25-£35 complete. So I'd check this, and also as Peter said worth checking the ignition over to eliminate as well. Lastly, the comment about stainless injector hoses also seems to crop here on the forum. I don't have experience myself but others suggest that they do have issues with heat-soak when a hot engine is tried to re-start after a stop. However I think that's only 10sec of churning to clear the petrol vapour not up to a minute. By the way, I would not recommend churning on the starter for more than say 15-20 seconds at a time. As they're designed for intermittent use, starter motors have no cooling fan so prolonged use can overheat and damage them. Hope this and the other comments help resolve your problem. good luck. J. Quote Link to post Share on other sites
hot-growler Posted July 23, 2014 Author Report Share Posted July 23, 2014 came to the car this evening after being laid up all day. all injectors squirted instantly. I let the pressure build up and all is well (one of the 6 was dribbling a touch but I have a spare) What stops the injectors injecting when engine is hot up and left for half an hour????? but then behaves the following mornig Quote Link to post Share on other sites
peejay4A Posted July 23, 2014 Report Share Posted July 23, 2014 Fuel vaporisation is a possible cause of that symptom and Phil asked a few posts ago if you have stainless braided injector hoses. Do you? I had this problem in my 6 and reverted to standard nylon pipes with no further problems. Quote Link to post Share on other sites
Peter Cobbold Posted July 23, 2014 Report Share Posted July 23, 2014 (edited) Vapour lock wherever the fuel is getting too hot. Hoses from MU - stainless braids are suspected by some. Then in boot: Pump having to provide 'suck' to pull fuel up from tank, or through too-small filter. Clogged filter. Cr*p fuel. Exhaust pipe too close to fuel pipe in chassis cruciform. Too hot weather ( but dont complain). Peter Edited July 23, 2014 by Peter Cobbold Quote Link to post Share on other sites
Ade_TR6 Posted July 23, 2014 Report Share Posted July 23, 2014 Had similar and traced it to a blocked filter, which in turn was caused by a disintegrating tank! Quote Link to post Share on other sites
hot-growler Posted July 23, 2014 Author Report Share Posted July 23, 2014 thought I'd mentioned the pipes, sorry, they are the standard non braided ones, ignition is lumenition electronic, so points not an issue. Left car outside for a couple of hours and tried starting! had to push it in the garage as usual!!!!! Will replace filter and check fuel pipes tomorrow. Bad Car! Quote Link to post Share on other sites
AndrewP Posted July 25, 2014 Report Share Posted July 25, 2014 Vapour lock wherever the fuel is getting too hot. Clogged filter. add to Peters list - blocked fuel tank breather. Try popping the fuel filler cap when hot. If you hear a hiss, and the car then starts, your fuel tank breather is blocked and/or restricted. Quote Link to post Share on other sites
peejay4A Posted July 25, 2014 Report Share Posted July 25, 2014 Check the fuel pressure, 104 psi at the metering unit. If it's low when running it'll be even lower during cranking. Check the integrity of the wiring from supply, through the inertia switch and back to the pump, also the pump earth. Lucas or Bosch pump? Quote Link to post Share on other sites
hot-growler Posted July 25, 2014 Author Report Share Posted July 25, 2014 lucas pump Quote Link to post Share on other sites
Peter Cobbold Posted July 25, 2014 Report Share Posted July 25, 2014 lucas pump Does it make a different sound when it fails to start (hot) compared with cold? Quote Link to post Share on other sites
hot-growler Posted July 25, 2014 Author Report Share Posted July 25, 2014 I haven't noticed any difference in tone hot or cold, I also don't hear ant change in tone as the pressure builds. Beautiful day today and TR6 in dog house! Will check fuel cap next time I dare get it hot. Quote Link to post Share on other sites
Peter Cobbold Posted July 25, 2014 Report Share Posted July 25, 2014 (edited) I haven't noticed any difference in tone hot or cold, I also don't hear ant change in tone as the pressure builds. That doesnt sound to me like vapour lock due to clogged filter or anything else wrong before the pump. Try giving the Pressure Relief Valve a thump next time it fails to start. If the PRV stuck part-open at switch-off it might kill injector squirting when starting hot. Maybe. If the shuttle stops shuttling in an MU that has heated up while standing (with engine hot) that would kill the injector squirts, even with normal fuel pressure. How old is the MU? Edited July 25, 2014 by Peter Cobbold Quote Link to post Share on other sites
peejay4A Posted July 26, 2014 Report Share Posted July 26, 2014 lucas pump Definitely check the pressure then, unless you know it's correct. Quote Link to post Share on other sites
jamesStag Posted July 26, 2014 Report Share Posted July 26, 2014 Hi Steve, Re your post #20, it seems odd that you don't notice any change in the Lucas pump pitch at switch on. assuming you have the original brass PRV, then there is a clever system in it that allows air/vapour to bleed through but then closes up when liquid fuel and pressure builds up. Hence on 'normal' switch on you should hear the pump run fast / high pitch for say around a second, then it should slow down significantly as it come up to pressure and the pump goes on-load. So I'd still suggest you check out the system pressure as from the problems you describe it sounds to me like the system might be vapour locking and hence not getting to pressure when hot. Thinking about it, another thing to check is could there be a blockage in the leak-off line from the PRV back to the fuel tank? This would have the same effect. So question on this is when the pump is running can you hear the leak-off fuel returning back into the fuel tank when listening from the fuel filler? (This is assuming that the leak off is returning to the top of the tank, and its not a new tank with an internal pipe returning fuel to a swirl pot in the base of the tank. Hope this helps. Let us know what you find. cheers, J. Quote Link to post Share on other sites
peejay4A Posted July 26, 2014 Report Share Posted July 26, 2014 I know I sound like a cracked record but there's no point in embarking upon a potentially lengthy poke and hope exercise unless you know that the pump and PRV are delivering the correct pressure at the MU at all times. Unless you find a wire that's dropped off that is. Quote Link to post Share on other sites
RobinTR6 Posted July 26, 2014 Report Share Posted July 26, 2014 Steve, where are you? Have you spoken to Raven Smith ? It's only that I have a pressure test kit to prove you have the right pressure at the MU. Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.