Running rough

[PIAA]

Hi

I need some advice before going even further into depression.

My TR6(CR)have started to run rough.

Saturday one week ago it went for 3 hour drive without any problems.

Yesterday we did a 1 hour trip still running nice and sweet (except the odd flat spots which I belive comes from poor butterfly alignment)

Starting her up again this morning all running rough, seems like just running on 4 or 5 pots.

She's got new Bosch pump and mu, new injectors, new hoses, new injector houses, new linkage all from Prestige. New ally tank from Andy Wiltshire. New Automec petrol pipes. New distributer cap, new rotor arm (red), new plugs, new plug leads, optical ignition, new sportscoil. Separate wires and relay to the pump.

The timing seems at the mark and stable. Only a few weeks since I bled and checked the injectors. All with nice cone spray. Pump pressure mesured today 109 psi.

When removing the plugs the were rather sooty, but all even and no particular plug better or worse.

I'll take out the injectors again tomorrow an check, can't understand now if any grit can come from anywhere since all new and have been running fine for a couple of full petrol tanks.

Any suggestions for what I should look into is most appreciated!

 

Regards from PI

[PILKIE]

if you havent done anything to it since it was running well last time then its hopefully something simple!

1st make sure your enrichment/choke lever hasnt stuck fully on,as this will make it run rough and cause sooty plugs!

[Jersey Royal]

Hi Piaa,

 

Good Idea on Daves part.

 

Also as new ally tank, was the tank flushed through prior to use? Its possible that

a few chards of ally from when the holes to mount the sender were drilled could remain, and

found there way to your filter.

 

Would be worth giving your pre filter a check and clean.

 

Clean the plugs see if that makes any difference, what plugs have you fitted?

 

Cheers

Guy

Edited August 21, 2010 by Jersey Royal

[peejay4A]

Before you take the injectors out try feeling the injector pipes. If the injectors are opening properly you will feel a definite pulsing in the injector pipe. If one or two are not pulsing then those are the injectors to remove and bleed.

Edited August 21, 2010 by HPA 510K

[PIAA]

Thanks for replys.

Injector pulses seems more or less even.

Cleaned plugs but did not make any difference, plugs are NGK BPR6ES.

Did inspect tank as far as possible but did not flush it when new. (It's been run through almost 3 full fillings without problems before today)

Choke is fully retracted

 

PI

[Lockley210]

Hi

I was stumped by a misfire for almost a year,chased the fuel system beliving it was fuel related only to discover it was a faulty optical ignition.

The unit had an internittent fault over 3000 revs, changed it and has been ok ever since.

Just a thought.

Mark

[PILKIE]

Bit of a long shot,but did you fill it up with fuel very close to home after your trip and just before parking it up?

You could of picked up some dodgy fuel?

Or,put diesel in by mistake!! Been there done that a few years ago!

Ended up chasing a non starting fault on my XJ6 all day until I sussed it out!

[PIAA]

It's not been filled, same petrol as yesterday.

I can of course suspect the points replacement unit, it's a one bought off e-bay but recommended here in the forum.

http://cgi.ebay.co.uk/AccuSpark-Triumph-TR6-electronic-Ignition-/230502781798?pt=UK_CarsParts_Vehicles_CarParts_SM

 

I also had the same symptoms earlier this summer. Then I found it to be caused by the inertia switch making the pump give low pressure. (changed it, put in relay kit etc and ran all OK afterwards).

Now I've put in an adaptor and bought a gauge to be able to mesure petrol pressure easy, the pressure is 109psi so that can't be the problem now.

Will the pressure still be OK if I have a block in the filter?

 

 

/pi

[PIAA]

I'm now trying to dig more into this problem. Looks like the plugs color is caused by overfuelling.

Picked off the return pipe from the MU at the tankside, no petrol is coming through when running the pump (not running the engine).

I thought it should be plenty of petrol running back to the tank through there anyway?

 

/pi

[PIAA]

Picked of the return pipe at the MU side too. Free flow through pipe back to the tank.

No petrol from the return outlet on the MU when running pump or when running engine.

 

More than thankful for any advice from here....

 

 

 

 

/PI

[peejay4A]

I suspect that most of the fuel is going via the PRV back into the tank if you're not running. You could try starting the engine but be prepared for a fuel spill. I've not tried this by the way.

[rodkaz]

hi ive just had the same thing no matter what i tried in the end it was my head gasket blown between 1 and 2 bores so just check the compersion a quick to do good luck rod

[PIAA]

Thanks Rod.

I'll do a new check of compression. Checked earlier this summer and then it was 200 and even at all 6 cylinders.

The rough running has been on and off, also before I did the compression test.

I started it again today to check and noticed that the choke operated (also lever back side of MU) but did not effect the running at all.

Like it's full choke all time.

The PRV is throwing petrol back into the tank as it should and the pressure at the MU is still stable at 109 psi with engine running or just pump running.

 

/PI

[Mike Collins]

Have you checked the vacuum at the MU? Low vac, more fuel.

 

I have run mine with the MU return line disconnected, very little fuel comes out, it's just a lubrication flow I believe.

 

Mike.

[PIAA]

Just to sum up the development in case there is useable info for others.

 

After talking to the always service minded Malcom Jones and with his advice the following has been performed:

Connected a CO meter, mesured the CO to be 7%

Adjusted the mixture until I got a stedy reading at 2,5%

This got no influence on how the car was running.

Changed all the plugs (all sooted but evenly) with new ones (same type NGK BP6ES)

Fired up and seemed like I've got a complete new engine. All seems to work fine.

 

Can it gradually build up soot on the plugs if the mix is far too rich, until it reach the point where there is hardly any sparks?

 

I'll have to drive her for a while now and carefully inspect the condition of the plugs to see what happens.

At least there is some hope, which of course will save some on the beer account (depression withdraws until next problem occurs!)

 

Regards from PI

[poolboy]

To help with reading the plugs:

http://www.dansmc.com/spark_plugs/spark_plugs_catalog.html

 

 

Here's mine. Maybe not perfect,but close.

Edited September 3, 2010 by poolboy

[Alec Pringle]

"Can it gradually build up soot on the plugs if the mix is far too rich, until it reach the point where there is hardly any sparks?"

 

Yes, indeed it can, all that carbon deposit conducts current away from where it's supposed to be - so you have a weak spark and poor running.

 

Soak the tips of the old plugs in brake fluid overnight (a good use for old brake fluid!), then scrub off the carbon with a toothbrush or nailbrush - it might even need a fine brass brush, like the ones you use on suede shoes. The plugs should work well enough after a good fast blast down the motorway.

 

Cheers,

 

Alec

[poolboy]

The only problem with brass is that it may leave tracks on the insulator that are conductive.

[Alec Pringle]

Indeed so, cautious brushing required !

 

Cheers,

 

Alec