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cotswold

New injectors fitted pump working - NO FUEL- WHY?

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Hi Charles,

Its a shame that you're finding the TR6 PI a bit of a challenge to get tuned, but do stick with it. In my opinion (and experience so far) once they are sorted they are then good & reliable.

 

When I bought my TR6 in 2012 I had the same symptoms as you. Full throttle good, idle fair, but light throttle and cruise very lumpy (to the point of only 4 cyl running almost). I think Rob Salisbury has the most likely issue. It was indeed butterfly sychronisation, in my case the linkage was all worn and so cyl 1 & 2 throttles were opening far later than the rest.

The tell-tale on my car was that I have a manifold/MU vacuum gauge. At part throttle the needle vibrated around badly as each time cyl 1 or 2 were on induction stroke the vacuum had a peak.

I re-bushed, and carefully setup the throttle linkages so everything was even and in synch. What an improvement!! Part throttle now steady and smooth on all cylinders, idle smoothness improved, and this was confirmed with a pretty steady vacuum gauge at part throttles.

 

The other tip (if you've not already done it) is to check the valve clearances before working on the butterflies. Again this relates to each cylinder taking in the same induction air and keeping everything in sych.

By the way, the reason idle can still be fair with this fault is that at idle the butterflies are almost completely shut, and most air is admitted through the brass idle screw and then down the throttle body balance tube, so this bypasses any butterfly issues.

 

So in conclusion, as vacuum gauges are not expensive I'd suggest buying one and T-ing it in to the MU vacuum line, and running a temporary pipe to the interior or somewhere you can see it while driving. This will tell you if butterfly synchronisation is the issue or not.

Also generally the MU don't have major issues, apart from seals potentially springing a leak, the design is such that each cylinder will get the same amount of fuel injected for a given vacuum. The issue is often butterfly setup so that the correct amount of induction air is also admitted to get the right fuel/air mix.

 

Hope this helps, and good luck.

Cheers,

J.

Edited by jamesStag

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Hi Charles,

Its a shame that you're finding the TR6 PI a bit of a challenge to get tuned, but do stick with it. In my opinion (and experience so far) once they are sorted they are then good & reliable.

 

When I bought my TR6 in 2012 I had the same symptoms as you. Full throttle good, idle fair, but light throttle and cruise very lumpy (to the point of only 4 cyl running almost). I think Rob Salisbury has the most likely issue. It was indeed butterfly sychronisation, in my case the linkage was all worn and so cyl 1 & 2 throttles were opening far later than the rest.

The tell-tale on my car was that I have a manifold/MU vacuum gauge. At part throttle the needle vibrated around badly as each time cyl 1 or 2 were on induction stroke the vacuum had a peak.

I re-bushed, and carefully setup the throttle linkages so everything was even and in synch. What an improvement!! Part throttle now steady and smooth on all cylinders, idle smoothness improved, and this was confirmed with a pretty steady vacuum gauge at part throttles.

 

The other tip (if you've not already done it) is to check the valve clearances before working on the butterflies. Again this relates to each cylinder taking in the same induction air and keeping everything in sych.

By the way, the reason idle can still be fair with this fault is that at idle the butterflies are almost completely shut, and most air is admitted through the brass idle screw and then down the throttle body balance tube, so this bypasses any butterfly issues.

 

So in conclusion, as vacuum gauges are not expensive I'd suggest buying one and T-ing it in to the MU vacuum line, and running a temporary pipe to the interior or somewhere you can see it while driving. This will tell you if butterfly synchronisation is the issue or not.

Also generally the MU don't have major issues, apart from seals potentially springing a leak, the design is such that each cylinder will get the same amount of fuel injected for a given vacuum. The issue is often butterfly setup so that the correct amount of induction air is also admitted to get the right fuel/air mix.

 

Hope this helps, and good luck.

Cheers,

J.

James that is very useful and thanks for taking the time to explain this. I had read somewhere that the Butterflies could be an issue but I think re-bushing etc may be a step to far for me. :( I know it will cost me but in the Spring I will take it to someone like Enginuity and have them test it. I bought the TR6 as I had a Vitesse in my 20s and loved the smooth 6 cylinder but as you say mine at the moment is almost like a 4 Cyl and actually less smooth at low speeds than my Velosolex French moped that purrs along at 15mph ha ha.

All the best

Charles :)

post-12736-0-95186900-1448026611_thumb.jpg

Edited by cotswold

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Hi Charles, Double check also the fire order at the spark plug point of view (1, 5, 3, 6, 2 ,4)

Best regards

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Ok, lets try an git you running, further to post aboot throttles,

what you need to find oot first is are the stupid rubber bushes still in the

linkage under the TBs, there 3 of em, even if they still thea, they will be well worn.

 

And spindals may be worn, its a case of when Ally rubs away / wears,it cause ally oxide,this is very hard and wears oot the brass on the spinnals,

its very rare for the TBs to be worn that much

Butt, the main reason for this is lack of lube,

Hands up any of you lot who ever lube yer throttles befoer every run ,

Non i bet,

 

Butt, even with thee,s probs, a decent go can be made by dooing it with a Vac gauge, NOT by setting watching the throttle openings.

 

Some of the movement int arm is not actually opening / turning the spinnal / s

but actually just shuv,n the arm upwards, as the brass is worn.

 

So, some throttles need to be set at a dif opening to others when looking at them actually opening.

 

By using a vac gauge on each set of manis, ye can see what the vac is pulling, at just off opening,

 

Set em all to as seen to be opening by eye, then actually using the vac gauge,

then they will almost always be miles out on some .

 

Ye gotta get the throttles just opening,so engine is running at say 1200rpms

then bung gauge on each cyl, and take a note, dont adjust till ye done all 6

 

then you will fin that 2 4 6 butterflies are getting most air,

and that maybe say 3-4 { middle set } is giving moer vac than others, so try and set so all are giving same,

when this is done, ye will fin that the throttle arms will most likely be opening the throttles at diff times, BUTT, the air flow will now be moer even, as the vac gauge has shown you this.

 

On an olde set I had, the middle one moved a 1/16th befoer the other 2,

most would think it were not synced up,, but it was, as it were tek,n into account the wear that was in that mani and links.

 

In short, the ones that are WORN will let moer air in

so, ye gott set the UN worn ones to open first ,to even things up, its simples really,

IF no Vac gauge, Use a bit of pipe bunged into yer MK1 lug ole

to listen to the ..hiss of air, gotta put pipe at same spot on each one though, to get same readings.

 

other thing, as long as the pipe on MU are correct, then put the pipes to the corresponding number ont manis, regardless of numbers ont ends, or your case, no numbers, simples

good luck

 

M

Edited by GT6M

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Charles,

 

I have a 1970 TR6 pi. I had the problem last year that from tickover when stationary, when I went to accelerate away (sensibily) the engine would stumble and jerk until the revs got up to say 1500'ish then the car would pull strongly.

 

After much poking and adjusting I eventually removed the air intake plenum and with the engine ticking over blocked each cylinder off in turn with the palm of my hand. Four cylinders just blocked off and made no real difference to the tick over. However two cylinders snatched my hand with the force of the induction and the engine stalled instantly.

 

Without load the engine was essentially ticking over on two cylinders and without enough revs to bring in the other cylinders the car could not pull away and would stall.

Palm of hand is not a particularly scientific but is quite sensitive and very cheap to use!​

 

I then made a manifold plug with normal vacuum gauge attached and measured the difference of each cylinder - quite a variation.

 

Eventually I bought a Weber Dellorto carb carburettor synchrometer about £35 which allowed me to equalise the vacuum on each cylinder. I found this difficult (impossible) to get exactly even, but a just a crude balancing made an unbelievable improvement.

Now variations in each cylinders vacuum might be valve adjustment, or badly adjusted throttle linkage, badly adjusted or worn butterflies as suggested above.
I'm Hereford'ish, if you would like to try a vacuum gauge I could bring one over tfor you to try.
Alan

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Cotswold: for the sake of £35'ish, I would buy one of those carb balancers off eBay, they're worth their weight in gold.

What I found was that if I balanced them on tickover she was still a little lumpy on take off, but, get the revs around 2000 rpm use the carb balancer & set those babies up & im sure you'll find a huge difference.

Don't give up, I had a dog of a runner but like you, replaced virtually everything & she's now as good as she's going to be!

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Tr 6! they realy put you to the test:-)

if it helps to reassure, I m on the same quest...

But again isn t that the fun if having a classic?

Keep in touch i'll tell you what I've done so far:-)

Jose

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Hi Charles,

Glad the initial post was of use. The thing is I wonder if you may have misunderstood what I meant by re-bushing? Like GT6M was talking about, this is not the spindles of the throttle bodies, but the throttle linkage. Now I've read your avatar details and I see your TR6 is a 1973, so I believe that's a CR series. In which case these are the later version of throttle that doesn't have the lower linkage shaft that my car ( a 1969 CP series) and that GT6M talked about that has the bushes. So please ignore that bit!

 

Is easy to check if you have CR series, as there are twin rubber balance pipes between each throttle body, whereas the CP series just has one.

You can see this from looking at the diagrams in the link below, the second and third pages.

http://www.rimmerbros.co.uk/ItemList--Triumph-TR6-Manifolds--m-13433

As PJM mentioned it is valid to check for leaks in those rubber hoses, but this mainly ends up as a rather high idle speed that can't be reduced, and poor idle smoothness, which I don't think you have.

 

However the general advice talked about to synchronise the butterflies is still valid. I think on a CR the linkage from the cable acts on the throttle spindles between cylinders 2 & 3. Then there is a link on the other end of that throttle body (cylinder 4) to the rear throttle body and cylinder 5. So I suspect wear in this system could mean that cyl 5 & 6 are lagging in terms of throttle opening behind the rest. Perhaps someone with a CR series car will post and add more detail (or perhaps search for CR series linkage setup and see what you find on here.)

Overall the point is that there is nothing vastly complicated here to adjust, and you are obviously reasonably competent with spanners given the work you have outlined in your opening post.

 

As others have said its worth buying a vacuum balancer / sychrometer (I also used an carb vacuum meter on each throttle choke in turn to help even all the throttles up)

 

I see you're not that far away in Moreton-in-marsh. I'm happy to chat on the phone if that helps. I'll send you a PM.

Cheers,

James.

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Thanks James I sent you a pm.

Cheers

Charles

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