TR6 running rich

[Corco]

Have recently bought a TR6 (car of my dreams for years) and to all intent’s it looks as if it has been really well looked after throughout it’s life, got a full folder/binder detailing everything that has ever been done to it. Prior to buying it, it seems as though it sat around for a while (in a showroom) before I bought it. 

The problem I have is that it is running very rich with the plugs being covered in carbon after only doing about four miles. Have done all the usual things, new plugs, leads, rotor arm and distributor cap and have also checked the timing and made sure the injectors are all functioning correctly.

Am at a bit of a loss now as to where to look next. Any advice will be gratefully recieved.

corco

[JohnD]

Corco,

You lucky man, you!     Lucas Pi tends to run lean at top revs, so the M/u is usually set to run a bit rich at lower engine speeds.    I suggest you don't treat it gently, but revv it, to at least 5K regularly!    That may clean up the plugs

[thescrapman]

Try slightly hotter plugs, BP5ES if you use NGK, or the Bosch 3prong ones, should help the plugs fouling.

And drive it hard, Pi cars are not for pootling round in.

[rlubikey]

Corco, all good advice above, but also have you checked the valve clearances? If they've closed up a little this will reduce the manifold vacuum which will make it run rich. Of course, if you have a vacuum gauge, connect it to the manifold (for example, disconnect the brake servo and use that port) and check the vacuum on idle. There are two different figures depending on whether yours is early (150bhp) or late (125bhp) but this is all in the service manual which you will find online in various places.

Good luck, Richard

[Pete Lewis]

sorry not a PI expert but if started on fuel enrichment/choke  it will take many miles  than 4 of driving to clear/burn the soot off the plugs 

pete

 

[Nigel Clark]

Hi Corco,

Most common cause of over rich Lucas PI is a sticking enrichment lever. This is the lever that one half of the twin choke cable attaches to on the side of the metering unit. Check that with the choke knob pushed right in, the enrichment lever sits against its end stop.

Another frequent cause of richness is an air leak in the inlet side. Check for damaged/split hoses between inlet manifold and servo or metering unit. Also check manifold gasket and metering unit diaphragm.

Nigel

[SpitFire6]

Hi,
I think that checking the plugs before the engine is at running temperature is futile.
Cheers,
Iain.

[PeteH]

I dont know how others do it, but I have always never checked plugs until after a good hot run, Switch off, No Idle. Then check?.

My only experience with Lucas PI, was towing a TR6 up and down the car deck of a RoRo Ferry, In Imminghan, in an attempt to get it to start for the ships electrician. That failed and it went home to Wales? on a Recovery.

Pete

[NonMember]

1 hour ago, PeteH said:

My only experience with Lucas PI, was towing a TR6 up and down the car deck of a RoRo Ferry, In Imminghan, in an attempt to get it to start for the ships electrician.

My experience of my PI estate, when it had a slightly tired fuel pump, was that while jump starting might well work, the bump method was a waste of time. The fuel pump would fail to deliver adequate pressure well before the battery was flat enough not to crank.

[PeteH]

3 hours ago, NonMember said:

My experience of my PI estate, when it had a slightly tired fuel pump, was that while jump starting might well work, the bump method was a waste of time. The fuel pump would fail to deliver adequate pressure well before the battery was flat enough not to crank.

He`d Been playing with it for hours, Flattened my "boost" trolley, (4 truck batteries, usually used to start "Dead" Truck`s in order to clear the loading decks). So it was Desperation time, I towed him with the 40t fork lift we had for containers. He finally got Loaded off to the far side of the UK at about 10pm!, That was one day of his leave already gone!.

Pete

[Corco]

Thank you for all the helpful advice, very much appreciated. All of the above suggestions have been checked through but it would appear that the metering unit is the cause of the problem. Am now in the market for a reconditioned unit and that should sort things out.

 

Corco

[thescrapman]

Try contacting Neil Ferguson for a recon on your unit, he is Stafford direction. 

[Corco]

Thank you 'thescrapman'. His name has come up before and have contacted him today. The MU is now off the car and am gettiing to him ASAP.

[Corco]

Quick update. Contacted Neil Ferguson and and got the MU over to him. Took him a couple of days but he identified the problem and sorted it out. Very impressed with price and explanation of what the problem was, would recommend him.

 

MU now back on the car and was out driving it this afternoon.