SlickV8 Posted June 23, 2023 Report Share Posted June 23, 2023 Hi all. I’ve a fuelling issue on my ‘73 Pi. I’ve upgraded fuel pump & PRV (I set pressure using a gauge to 107psi) to new and trying to bleed injectors. I’ve eventually got fuel in all 6 of them and they all drip when hung up from bonnet with fuel pump on. it sometimes starts with a dose of ‘easy start’ but runs like a bag of spanner’s then dies. I’m sure no fuel to a few cylinders. When I remove injectors / disconnect coil and turn it over I get a short cone from one injector then nothing until I release the key at which point another injector fires. Occasionally 2 or 3 seem to fire in rapid succession but only when I release the ignition key from the start position. Ive seen all 6 fire at some point so they all work) So my query is that I turn the key and get one injector fire but then no injectors firing at all while the engine is cranking then 1 or 2 fire as I release the key. is that right? Have I miss-timed something or do I just need keep at it? Battery flat now so off for a beer while it charges overnight but advice would be most appreciated. thanks I’ve tried to add a short clip to show you Nick 70923454584__89F586AB-54E5-4975-B989-86D1210C5E97.MOV Quote Link to post Share on other sites
peejay4A Posted June 23, 2023 Report Share Posted June 23, 2023 Has it ever run? It seems as though the shuttle in the metering unit is stuck or the plastic drive dog is broken. Quote Link to post Share on other sites
Peter Cobbold Posted June 23, 2023 Report Share Posted June 23, 2023 +1 Quote Link to post Share on other sites
SlickV8 Posted June 23, 2023 Author Report Share Posted June 23, 2023 Interesting. So yes it’s run previously. It was an unfinished project, I got it running about 2 months ago (ran great) then one day it just wouldn’t start. The old prv was leaking anyway so I took the opportunity to redo the fuel system. The MU had a leaking union so I took them all off and refitted them. I’m confident the red plastic thing is fine. What’s the shuttle in the MU, how do I get to it & is it serviceable? thank you. Quote Link to post Share on other sites
Mike C Posted June 23, 2023 Report Share Posted June 23, 2023 (edited) 14 hours ago, peejay4A said: Has it ever run? It seems as though the shuttle in the metering unit is stuck or the plastic drive dog is broken. +1. The Lucas PI system is totally mechanical, there are no electronic components switching it on and off. Have a look here: https://app.box.com/s/zz3e6x4gr4u7t360makeqbm0adxr4cu9 Edited June 24, 2023 by Mike C Quote Link to post Share on other sites
Rob Salisbury Posted June 23, 2023 Report Share Posted June 23, 2023 The shuttle is a small aluminum "bullet" lurking deep in the heart of the metering unit that is swept back and forth by fuel pressure delivering precise quantities of fuel to each of the 6 outlet unions as the rotor turns, without specialist equipment and a detailed knowledge of how the whole metering unit is assembled then getting to the shuttle is beyond the realms of most people, I'm not saying it can't be done (I've taken a couple apart and got them working again) but it's not for the faint hearted, best to get the thing refurbished and recalibrated. Cheers Rob Quote Link to post Share on other sites
SlickV8 Posted June 23, 2023 Author Report Share Posted June 23, 2023 Thats all really helpful, thank you all for your advice. I've actually got a refurbed MU I was saving for a second TR6 I have waiting to be rebuilt when this ones finished. I'll swap it in tmrw and report back. Quote Link to post Share on other sites
TR NIALL Posted June 24, 2023 Report Share Posted June 24, 2023 10 hours ago, SlickV8 said: Interesting. So yes it’s run previously. It was an unfinished project, I got it running about 2 months ago (ran great) then one day it just wouldn’t start. The old prv was leaking anyway so I took the opportunity to redo the fuel system. The MU had a leaking union so I took them all off and refitted them. I’m confident the red plastic thing is fine. What’s the shuttle in the MU, how do I get to it & is it serviceable? thank you. The Shuttle and yes they can be slightly different. Quote Link to post Share on other sites
Mk2 Chopper Posted June 24, 2023 Report Share Posted June 24, 2023 I can only imagine turning the ignition off which will turn the pump off somehow allows pressure to be released and you see a pulse from an injector, doesn't really make much sense to me as its fully mechanical, so needs to be turning combined with the fuel pressure and the shuttle space containing the amount of fuel to be pushed via the rotor into one of the six injector lines. In any case it seems the problem started before you changed anything. So I would think it's worth substituting the MU for the refurbished one, make sure it's timed correctly to give yourself the best chance. Also if you can back fill each injector line with fuel, it'll save a bit of time priming the system. It's good to regularly start the car as the fuel lubricates the shuttle and this newer fuel doesn't seem to like sitting so long as the old stuff. Good luck and report back on what happens. Gareth Quote Link to post Share on other sites
peejay4A Posted June 24, 2023 Report Share Posted June 24, 2023 Also suspect the non return valves in the MU connectors. Quote Link to post Share on other sites
john.r.davies Posted June 24, 2023 Report Share Posted June 24, 2023 Slick, There are a few dealers around who have the kit to calibrate a Lucas Pi metering unit, according to the instructions in the Lucas manual (link from Mike C, above. See also: Lucas Mk1 and Mk2 manuals, notes, drawings, etc. (https://www.lucasinjection.com/) ) I would suggest that you take off the M/u and send it to one of them for servicing and calibration. You're in Southport, and I would have previously recommended Malcolm at Prestige Injection, but he has retired, and his business taken on by Carl Fitchett at TR Trader. I haven't had Carl calibrate one of mine, but he has been knowledgeable and helpful with other Pi matters. And he's based in Stockport, even nearer to you than Malcolm used to be! See: https://www.trtrader.com/ OH! Just seen your post, that you have a rebuilt M/u and intend to fit that! Go for it! My other query is, did the rebuilt unit have Viton seals fitted? Modern alcohol fuel demands them. Good luck! John Quote Link to post Share on other sites
JohnC Posted June 24, 2023 Report Share Posted June 24, 2023 Going out on a (very short) limb here. It is not the shuttle. If that were stuck you'd get nothing. I suspect you damaged some seals when you removed and replaced the unions. As a rule, I don't take apart the MU unless I have replacements for all the seals & O-rings (the barrel shaped seals in particular). They get deformed and harden over time and are easily damaged on reassembly. You may have done that when you removed and replaced the unions. A strong indicator of that is the dripping with the ignition on. There should be zero flow from the injectors if the engine isn't running. If there is, then high-pressure fuel is making its way between the rotor and sleeve or between sleeve and MU body, and into the injector lines. Fit the recon PI, make sure you have a healthy and well-charged battery, check the fuel pressure *when cranking* and then give it a whirl. JC Quote Link to post Share on other sites
SlickV8 Posted June 24, 2023 Author Report Share Posted June 24, 2023 Refurbished MU fitted and it started with little fuss. Only problem now is it’s lumpy at idle and I think running very lean. I plumbed a vacuum gauge in between MU & inlet manifold and best reading I can tease from rotating the distributor is 12hg, I believe it should be 15+? I’ve sprayed carb cleaner over every joint & can’t find any obvious vacuum leaks. I’ve balanced the TB’s so they’re all equal (all around 5kg on the balancer scale) but it doesn’t want to idle at all comfortably and does that hollow boggy ‘dooooohhhh’ thing when you open the throttle before seemingly revving freely at higher rpm. Although blipping it gets a few backfires through inlet 1 & 2 I’m hoping to get back on it tmrw afternoon, first job is check all the injectors are def producing a good fan….. Quote Link to post Share on other sites
Mike C Posted June 24, 2023 Report Share Posted June 24, 2023 My TR6 has always had 10" Hg of vacuum at idle, measured at the brake booster connection. It's bored to 2.7 litres and fitted with a TR5 cam plus other bits and pieces. Note the MU should be calibrated to suit the engine- you can't really swap them between engines of different build & tune. Quote Link to post Share on other sites
SlickV8 Posted June 25, 2023 Author Report Share Posted June 25, 2023 Injector 6 had some small droplets in the fan so swapped it out for a spare old one I had on the shelf. Definitely improved things but it’s still no comfortable idling below 11-1200. The TB’s now balance at approx 2.5kg across all but 5&6 seem to fall away below 1000 rpm. Daft question; is the aim to have the idle speed screw fully closed? Best I can get is idling around 1100 with fast idle screw out a little over 1/2 turn. It’s still lumpy on initial throttle. it’s also happier with a touch of choke on. I’ve ordered a set of replacement injectors so I’ll see what difference that makes next week when they arrive. Quote Link to post Share on other sites
SlickV8 Posted June 25, 2023 Author Report Share Posted June 25, 2023 On 6/24/2023 at 10:34 AM, JohnC said: Going out on a (very short) limb here. It is not the shuttle. If that were stuck you'd get nothing. I suspect you damaged some seals when you removed and replaced the unions. As a rule, I don't take apart the MU unless I have replacements for all the seals & O-rings (the barrel shaped seals in particular). They get deformed and harden over time and are easily damaged on reassembly. You may have done that when you removed and replaced the unions. A strong indicator of that is the dripping with the ignition on. There should be zero flow from the injectors if the engine isn't running. If there is, then high-pressure fuel is making its way between the rotor and sleeve or between sleeve and MU body, and into the injector lines. Fit the recon PI, make sure you have a healthy and well-charged battery, check the fuel pressure *when cranking* and then give it a whirl. JC Hi John. I thought the aim of bleeding the injectors was to string them up & run fuel pump until they are all dripping?? Quote Link to post Share on other sites
SlickV8 Posted June 25, 2023 Author Report Share Posted June 25, 2023 Quick update. My next TR6 project is sat waiting at back of garage. I drove it home 12 months ago noting it seemed to run great but clutch was goosed; just nicked the injectors out of it and current one now seems to be pretty well sorted!! I’ve never driven it but just back from a very agreeable blast up a local farm track. No seats/interior so awkward but hit 60 no trouble although my assumption that I’d bled the brakes properly needs revisiting. I’m calling it a day now, like to finish on a high ill be interested to see how it cold starts tmrw but I’ll keep this updated. Thanks again for all your suggestions & advice Quote Link to post Share on other sites
Mk2 Chopper Posted June 25, 2023 Report Share Posted June 25, 2023 4 hours ago, SlickV8 said: Daft question; is the aim to have the idle speed screw fully closed? Best I can get is idling around 1100 with fast idle screw out a little over 1/2 turn. It’s still lumpy on initial throttle. it’s also happier with a touch of choke on. No the idea is to have the throttle plates (butterfly's) shut and to introduce air via the bleed screw hopefully getting around 750 - 850 rpm when it's adjusted correctly. Gareth Quote Link to post Share on other sites
ntc Posted June 25, 2023 Report Share Posted June 25, 2023 If the plates are shut the throttle bodies will become scrap Quote Link to post Share on other sites
Mk2 Chopper Posted June 25, 2023 Report Share Posted June 25, 2023 20 minutes ago, ntc said: If the plates are shut the throttle bodies will become scrap Yes, I didn't mean they were scraping their way into the throttle body, but good to point that out. Gareth Quote Link to post Share on other sites
Steve-B Posted June 25, 2023 Report Share Posted June 25, 2023 7 hours ago, SlickV8 said: Hi John. I thought the aim of bleeding the injectors was to string them up & run fuel pump until they are all dripping?? When I got ours back from reconditioning by Mike Bilney he recommended putting a thimble of petrol in each injector before attaching to the injector line then insert it. Don’t fully tighten the pipe but tap ignition 5 secs THEN bleed and tighten down. I’m still learning a lot about PI but it made sense and car started straight away. YMMV Quote Link to post Share on other sites
john.r.davies Posted June 25, 2023 Report Share Posted June 25, 2023 4 hours ago, ntc said: If the plates are shut the throttle bodies will become scrap Please explain how, ntc? The test used to be that the discs would grip a cigarette paper. Now I haven't smoked (anything!) for forty years, it's the thinnest feeler guage in the box, like half a thou. Quote Link to post Share on other sites
ntc Posted June 25, 2023 Report Share Posted June 25, 2023 Do a search I remember seeing you trying to set yours at Mallory years ago with feelers they require 2th clearance or you will ridge the bodies if you go to Racetorations there is two good old tea chests full of them probably cashed in for scrap now Quote Link to post Share on other sites
john.r.davies Posted June 26, 2023 Report Share Posted June 26, 2023 14 hours ago, ntc said: Just checked; cigarette papers come in different weights/thickness. A Green Rizla is a bit less than 1 thou. Quote Link to post Share on other sites
PodOne Posted June 26, 2023 Report Share Posted June 26, 2023 I've always sprayed Molycoat on the butterflies or throttle plates to seal any gaps once cleaned or on new set ups to replace the long term carbon which builds up with use. Done the same with this car and the idle was surprisingly good on start up. I suspect achieving a uniform clearance to 1-2 Thou 50 years ago was a bit problematic although I might be wrong! Andy 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.