TR6 PI - some technical issues 

I already commented a while back on the other part on the TR6. My father was main mechanic for British Leyland and indeed the fuel pump was troublesome. It was basically a wipermotor that was slightly tweaked and used as a high pressure fuel pump which made it suffer and get hot. The original factory solution was to use an extra serpentine fuel hose on the OUTSIDE of the pump where fresh fuel went through so to keep the pump cool. Honestly never heard of the loop you are telling that the pump heated up the fuel. It was the other way round. The fresh fuel as always cold was intended as a natural way of keeping cool the pump, but still the pump went hot. It didn’t heat the fuel though, it just got hot. Very good video and enjoyed watching it! In all honesty, still having some family owned Triumphs and other British cars, I must really say that if you know what you are doing, actually the cars are more reliable than everyone wants to believe.

Hi, Nice video and generally good explanation. However I have to say that the Lucas PI injection does not have to be that troublesome. In my opinion repeated failures of the metering unit drive dog is very unusual and I'm certain there's something wrong with your metering unit rotor. (As you say the drive dog is the mechanical 'fuse' to protect the drive system). Have you had your metering unit refurbished? Have a look on the TR6 Forum of the register in the UK. Lots of info and help on there. There are people who refurbish these still, typically Neil Ferguson or Prestige Injection for about £175. They should get you sorted out so you can enjoy the car properly. Oh and the poor cold starting with fuel bleed back: that's likely to be failing non-return valves in the metering unit too, another reason to get it refurbished. Next day cold starting should almost be instantaneous. If left for a week, that might take 5-10secs to prime, fair enough... Enjoy your TR6!!!

Re: Back in the day... In the late 70's I owned a TR5 PI. It was one of the pre-production prototypes, chassis number CP6. One of the cars that got loaned out to journalists for reviews/testing. The fuel pump was mounted in the engine bay, close to where the brake master cylinder was positioned. Surrounding it was a coiled cooling ring. The only time I ever had any problems was if, on a very hot summer day, I was caught in heavy, stop start, traffic jam ups..., the engine would start to hiccup, and intermittently fade, due to the fuel vapourisation that you describe. The cure was to pull into the side of the road, and let things cool down a bit, and preferably when the traffic snarl had eased and got moving again. In 4 years ownership, this problem manifested only about 3 or so times. So hardly a big deal. Re: the "... bit more power on the PI...". Somewhat more than a bit. The early TR6 PI's, as with the TR5, had 150bhp. The carbed versions that went to America were so strangled that, as I recall, they only had about 105 bhp, much the same as the TR4's from years prior.

Well , that's the love of triumph for you , its a beautiful car for sure 👌👍

I had a 1971 TR6 from new, and kept it seven years. Only fuel problem in that time was a blocked injector - a simple swop. Never had cold starting problems, and the fuel system received zero servicing. It did get through three water pumps, the quality of which deteriorated at every exchange (from casting to pressing).

Interesting video! We have had our 6 for over 25 years and until fairly recently the fuel system was ok, only needing injectors clearing and a refurb to the metering unit. However, knowing we had 2 TRips accepts the Chanel this year, I decided to replace the 21 year old Bosch pump. I was unable to find an exact match and, on advice, replaced it with a Sytec 3044. There were initial positioning issues - down to me but eventually had it sorted - or so I thought! I had all the issues you described in the video. Eventually I mounted the pump in the wheel arch with a Facet low pressure feed pump with built in filter directly beneath the fuel tank. I have removed any obstruction like the fuel tap that had been on for 25 years and ensured all pipework was 12mm id for maximum flow. I have fitted a Sytec serviceable post filter with an 8mm replaceable filter. There have been no overheating issues that the various pumps I used this year suffered with. Do my recommendation is forget the fuel hungry 3044 pump - either Bosch or Sytec. I am now using a Sytec OTP 979 fed by the low pressure pump as described. Fueling is massively improved with startup and running much smoother due to the low pressure feed. Looking forward to the French and German meetings in May 2024.

James makes some good points. Also noticed some minor backfiring on gear shifts which should not happen. I've had mine since new (1969 build) in Australia without any problems other than replacing worn out pump brushes. Pi system is difficult to get right, but, works well for a mechanical system when dialed in.

Love my TR6, use it more than any of my other classics. Mine is on twin SUs

Never had a moments problems with the actual injection system, and I used to drive it like it was stolen; maybe that's the secret! That damn fuel pump, otoh, my god, it used to overheat until it seized, and I'd have to wait until it had cooled down to get going again. I'd still own one again, but prices have gone crazy.

1974 used to go on deliveries with a guy who had a tr6. Heavy boxes of engineering parts in the boot , never got far before pump over heated.

Absolutely love the TR6, but in this day and age I would pull the head have it ported and put an after market EFI system on. Being from the US the carburetors are a little to fussy and never really saw the full performance that said my brother had his first TR6 back in the 70's and my dream is a deep Navy Blue with saddle interior and a crisp fall morning. 😊

Oh wow ,that exhaust note,love it!!

The reason the rotor drive fails, is the unleaded petrol, which causes it to seize. Since I add a little amount of led substitute to the petrol, despite of the converted valves, I never had any failure to complain about anymore. It is working trouble-free for years.

You're up to 808 subscribers now. Whoo hoo! 😆 Where are you and are these things all this noisy? No muffler? Lukas is bad joojoo. How did the carburated ones run? I remember friends having Triumphs and MGs back in the early 70s, and they were a lot of fun but real pains in the ass to keep running.

My first 2 cars were TR-6s. Endless mech troubles and graduated to Mercedes 280SL. No regrets. Granted that was 30 years ago when prices were similar.

I have a triumph 2.5PI which I drove in S Africa for several years - never had a problem with the fuel pump even in the Karoo at 45C!

Very intelligent explanation

Hi! You are a real connaiseur of these cars! Very 🧐 interesting. I had a tr6 which had very bad problems...👍🙋🥀🇨🇦

7:00 ah, good old vapor lock... old Citroens have this problem too, also with carbs. Experienced this many times. Cold start = fine. Immediate hot start = fine.. but 10 min grocery stop...? 😓

They're must've been some problems with the R53 by now, mine's currently refusing to work and is in the shop right now. I'd love to see a video on technical issues with that car! Either way, I could listen to you talk about car stuff for hours. Make more videos!!

the easiest and cheapest way to solve the problem is to add a second fuel pump, for example a small FACET and you can ride until the trunk is empty

Well it is a classic, but I'm sure the goods outweigh the bads.

Very good

I had the 2.5 PI sedan. Changing the rubber O rings in the injectors to viton O rings solved 90% of the problems. Never had any issues with smell of petrol in the boot. I made a a water cooler for my fuel pump motor that solved the vapour lock problem. All up cost less than $20 in the 80's. I drove mine on 45 deg C days in Aus summer no worries. Never knew anyone who had the issue with the red plastic piece. Maybe some issues are caused by unleaded fuels?

Many thanks Michael for these excellent technical explanations on the PI variant of the TR6. Also great sounds on the road, what is your exhaust system ?

I don’t get you stopped posting content or why you have so few subscribers in comparison to views! You make great content

Where did you get a clock for your dash that matches the gauges?

What color is is this car?

Had a PI only 2 good people can get them spot on so i’m now driving an import on SUs believe me it’s slower but i’d never own another temperamental injection car

Sadly from 2030 on all combustion cars including classics will be banned from public streets in EU :-( In Germany the Green party gave order to shorten fuel supply from 2025 on by reducing petrol stations to only one single state operated central gasstation per city. :-(((

Lucas never had any good reputation for Fuel Injection nor Fuel Pumps. The fact it was not available on US Exports appears to be quite certain it would have never been able to comply with US Emission Requirements in addition to the fact High Temperatures and High Mileages would have been a total disaster. England's automotive industry over the past 4 decades went down the toilet, as well as every other industry with the exception of Weapons and Turbo Jet Engines ! How pathetic

Having had a TR6 PI Mk1 for 5 years starting 1972 and driving on autobahns at high speed regularly, I can only describe them as a "Bag of Poo" and that's being polite!