Injectors and poss stale petrol

[chrisredtr6]

Dear forum,

A bit of expert opinion needed pls.

Car: 1974 CR TR6 with recent Bosch fuel pump and PRV from Moss Europe.

In December 2011 it conked out and after detective work it was time for a recon metering unit, and new injector seals. So replaced these last spring via Neil Ferguson and Chris Witor respectively.

 

However, due to being too busy and one of the worst summers ever in terms of weather I didn't get the chance to bleed the system correctly and actually get the car started last year.

 

So, fast forward to the weekend just gone, and the first free weekend I've had for ages I bled at least four of the injectors as per the great instructions on the forum. The car wouldn't quite start though (although very nearly, it was definitely firing)..

 

The last time I put petrol in it was Dec 2011. Is it likely that the octane levels have dropped over the last 16 months and this is the problem? The tank is nowhere near full btw. I've read lots of stories about unleaded only lasting a few months before causing probs so I'm wondering if this is the culprit?

 

Thanks all in advance.

 

Chris

 

 

 

 

[Tony Millward]

Hi Chris,

 

Definitely put some fresh fuel in.

 

Tony

[chrisredtr6]

Tony,

Thanks for the reply- I think you're right. Oh well at least I don't need to buy any de-greaser for a while..

Chris

[PJM]

Fresh fuel needed, I had a TR7 that would not start on fuel that was about 3 months old, as soon as we had a fresh gallon it fired first time.

Edited April 8, 2013 by PJM

[chrisredtr6]

Dear forum

 

I know its been a while but the stale fuel was definitely the culprit. I drained the old fuel out and put a couple of fresh gallons in and it fired right up. So a useful reference for anyone as this is an easy thing to overlook. Thanks for the replies on this.

 

However whilst it starts no problem now and is firing on all 6, its running far too rich, as its chucking out black smoke and the plugs are blackening straight away. Is there any adjustment with a metering unit? I remember telling Neil Ferguson when he reconditioned it that it was for a 125hp car so I'm assuming it is set correctly. Assuming the metering unit is all good I thought that the rich mixture is perhaps due to lack of air as opposed to too much fuel. So I took off the 'Triumph' embossed inlet manifold to expose the butterfly valves and none of them are jammed or sticking. Is it likely that these now need to be calibrated or adjusted to the new metering unit?

 

Chris

[Peter Cobbold]

Check the 'choke' lever on the MU is returning to its proper off position. Sometimes the outer Boden cable jumps out of its clipon the MU, keeping the inner one 'shorter' and the 'choke' ( aka excess fuel control ) on.

Edited June 1, 2013 by Peter Cobbold

[chrisredtr6]

Hi Peter

 

I did check this - and because the cable is a bit on the old side the lever was slightly 'on' giving slightly more fuel so I disconnected it completely (engine was warm) thus the lever returned completely. But I started it again and still the black smoke. It didn't seem to make much difference.. (But I'll be getting a new cable on Monday)

 

Chris

[Peter Cobbold]

Hi Peter

 

I did check this - and because the cable is a bit on the old side the lever was slightly 'on' giving slightly more fuel so I disconnected it completely (engine was warm) thus the lever returned completely. But I started it again and still the black smoke. It didn't seem to make much difference.. (But I'll be getting a new cable on Monday)

 

Chris

Chris,

Assuming the hose from the manifold to MU is air-tight and that the diaphrgam has not split ( its brand new) then I think something has seized during standing.

It might be the PRV - so give it a good thump wth engine running.

The problem with old fuel isnt octane loss as evaporation of the volatiles that help starting. But after a year with old fuel in it another possibility is that the ethanol in the fuel has picked up water, oxidised to acetic acid and started to rust the fuel system. It may be that the MU is now not in new condition. Perhaps the moving end stop that controls shuttle motion as siezed in the rich position. The MU rotor's innards are very high precision and dont take kindly to standing. You can try taking off the plasic cover on the MU and pushing the projecting steel cam follower back into the MU - its cylindrical and the two rollers run acoss it. Do this with engine off no fuel pressure.

cheers

Peter

 

edit: thats the rectangular plastic cover on the side.

Edited June 1, 2013 by Peter Cobbold

[chrisredtr6]

Thanks Peter for your reply I will take a look at this.. and report back..

 

Kind regards

Chris

[chrisredtr6]

I removed the cover and it all seemed to be moving freely inside, so hopefully corrosion isn't causing a problem here. I've tapped the prv too but still plenty of black smoke. Any other ideas greatly appreciated, regards chris

[Peter Cobbold]

Fuel pressure may be excessive. This is set by the PRV, so:

At tick-over check the PRV is dumping fuel by listening to the pump while very briefly, no more than a second or so, clamping the return hose from PRV to tank. If the PRV is not working the pump note will not change. In which case thump it hard. If thats doesn't free it, report back, someone will have tackled one, successfully.

Ideally, measure fuel pressure at MU inlet - need to borrow kit from member local to you.

Although 'recent', the PRV might have seized during standing while partially filled with fuel.

 

 

Dont ignore ignition -check sparks, static timing, fit fresh plugs.

Edited June 9, 2013 by Peter Cobbold

[chrisredtr6]

Hi Peter

 

Thanks for the reply - I'll take a look and report back

 

Regards

 

Chris

[chrisredtr6]

By way of a follow up I think that the PRV is not working correctly - but measuring the fuel pressure is going to be my only way to solve this. I've read quite a few postings on making your own pressure guage - is this still the most cost effective way? Or can anyone recommend a decent off-the-shelf guage that will not break the bank

 

Thanks again.

 

Chris

[Quentin]

Try this 5 minute job

 

On top of the MU there is a black plastic cap held on by two screws. Remove these and lift off the cap. There is a stack of three adjustment screws each with a locknut, There is no black art associated with this. Carefully mark the position of everything with a permanent marker - drawing a single straight line down all. Then you can always return it to the starting position position afterward.

 

Unlock the bottom one (A1 in the Lucas manual I can email you if you want). A tap with a carefully placed screwdriver and hammer will do fine. This allows all three to be rotated as a single unit (don't unlock the other ones). Rotate anti-clockwise a half turn. Tighten the lock nut and refit the plastic cover. Makes sure the screws are fully seated again as you will lose vacuum otherwise. You have now leaned the mixture across the whole range. It was Neil Ferguson who first told me to do this, though in my case I needed to richen it up to compensate for hesitation going from idle. In my case, although my car is a CP I thought (wrongly) it might have a CR cam)

 

Would you like the Lucas Manual? If so, PM me.

 

It is really easy to adjust the mixture this way. You will notice the difference when you get it right.

 

By the way, have you checked vacuum?

Cheers

Quentin

[chrisredtr6]

Thanks Quentin, I'll give this a try - although cannot do until after the weekend as we're away visiting friends.

I checked the vacuum hose to the MU, and it was ok - no splits or anything. I still need to check the fuel pressure - but your method sounds like an option too. I'll PM you for the manual. Thanks for your help!

 

Cheers,
Chris

[Peter Cobbold]

Chris,

Dont do Quentin's adjustments until the fuel psi is right. His fix is fine for small psi errors.

Looks like its the PRV at fault and you are getting a lot of extra pressure.

Thump the PRV between two hammers to try to shock it free, pump running. If that doesn't work,the PRV comes apart between the two steel hexes. There's a white nylon screw inside IIRC, turn it to and fro then return to original position! I might be wrong its about 30 years ago I adjusted the psi. Or simply get a replacement.

Peter

[chrisredtr6]

Yep, will do thanks Peter. I need to get myself a fuel pressure testing gauge..

[Peter Cobbold]

Yep, will do thanks Peter. I need to get myself a fuel pressure testing gauge..

Yes, nothing like a measurement for fault finding, removes a host of guesswork.

Peter

[RobinTR6]

If you need I can look for the invoice for mine, all plumbed in with a take off point. About 60 quid. Well worth the investment. It's got the list of bits and the supplier, ordered by phone. Very helpful chap too.

[RobinTR6]

Just in case.

 

Hydrotechnik tel 01159 003 550

 

Parts

 

! SNA02 3/8 BSP male swivel test tee piece

! S100-AC-FA-02.00 DN2 -400bar microbore hose assembly, 1620 Female to 1/4 BSP gauge female hose ends

1 9801-160 63mm Pressure gauge g1 1/4 BSP bottom entry

 

Costs incl postage £57.82...you could save a tenner with a shorter hose, I went for 2 metres so I could see it inside car.

 

Took about 30 mins to connect up. Leaves the take off on the entry to the MU and that means you can connect the gauge to test and disconnect in a minute so easy to test whenever without any further work.

 

As I said very helpful guy on phone and parts are well made and work perfectly.

[Velo-felo]

Quentin, your 5 minute adjustment trick... My 6 seems to be generally sooty, fuel consumption is poor and at the last MOT the guy said it was too rich for the test but let it go. It runs ok and drives really well but I wondered if a tweak as per your instructions is worth a try?

Steve

[Quentin]

Uh oh. Chris was looking for expert advice. Anyone who has seen, or had the courtesy to answer, some of my dumb questions in the past would be amused methinks! I only dared make a suggestion because it is easy and easily reversable...and worked for me. On which basis I would say why not? Real experts can probably advise whether you should try other things first. There have been other posts about adjusting mixture, quite recently i think. I just can't remember who by and when.

Quentin.

 

Found it: It was this post

 

http://www.tr-register.co.uk/forums/index.php?/topic/36188-pi-mu-not-always-a-bad-thing-to-adjust/

Edited June 23, 2013 by Quentin

[chrisredtr6]

Just in case.

 

Hydrotechnik tel 01159 003 550

 

Parts

 

! SNA02 3/8 BSP male swivel test tee piece

! S100-AC-FA-02.00 DN2 -400bar microbore hose assembly, 1620 Female to 1/4 BSP gauge female hose ends

1 9801-160 63mm Pressure gauge g1 1/4 BSP bottom entry

 

Costs incl postage £57.82...you could save a tenner with a shorter hose, I went for 2 metres so I could see it inside car.

 

Took about 30 mins to connect up. Leaves the take off on the entry to the MU and that means you can connect the gauge to test and disconnect in a minute so easy to test whenever without any further work.

 

As I said very helpful guy on phone and parts are well made and work perfectly.

 

Thanks Robin - really helpful,

Regards

Chris

[Velo-felo]

Quentin, your 5 minute adjustment trick... My 6 seems to be generally sooty, fuel consumption is poor and at the last MOT the guy said it was too rich for the test but let it go. It runs ok and drives really well but I wondered if a tweak as per your instructions is worth a try?

Steve

Well I'll give it a go... As you say it can go back to its original setting easily enough. I don't have any fancy meters or anything to test the result just checking of plug colour, I suppose that's good enough?

Steve