Metering Unit

[TR674]

Hi good people, I have a curious fuel issue. After a lengthy period of running well, car started running a bit rough, then would occasionally cut out when at running temp but would re-start O.K. Then whilst driving for a few weeks of rough running, I experienced what seems like total fuel starvation, like I just turned off the ignition whilst driving. Would not restart until cold. Not even a cough, just dead like no fuel.

It's been sitting for a few months since. So last weekend I took it for a drive, and once upto temp, it cut out suddenly. No cough or splutter, just off. Wouldn't start until I applied a little choke, then ran normally. As soon as I pushing in the choke, motor stopped dead. Then once cold, started up O.K.

Tank is 1/2 full, battery fully charged and no visible fuel leak. Original Lucas pump running fine (no elec fault-like dodgy wiring).

Any ideas?

[cp25616]

First thing I would do, as the symtoms all add up is to change the coil. As soon as a defective coil gets to a certain temperature, and from what you have stated it runs fine until it gets warm, you have nothing, no spark means no go.

Yes it might be something fuel related but I would replace coil first and if that doesn't work move onto something else.

Alan G

[Mk2 Chopper]

I would say the same try a substitute coil first. If that doesn't work, do the basic checks including if you have a spark at the plugs and spray coming from injectors when engine is cranking . 

Gareth

[TR674]

Many thanks. For some reason my mind went straight for fuel. A job for the Easter weekend.

[Waldi]

If it was fuel starvation pulling the choke would help. Next time it stops:

1) check if you feel the plastic fuel lines to the injectors pulsing. If they do there will likely be enough fuel.

2) see if it sparks; best to remove one spark plug cap and stick a good plug in there and ground to the block while cranking. If it sparks it’s probably not ignition related.

Waldi

 

[Mike C]

9 hours ago, Waldi said:

If it was fuel starvation pulling the choke would help. Next time it stops:

1) check if you feel the plastic fuel lines to the injectors pulsing. If they do there will likely be enough fuel.

2) see if it sparks; best to remove one spark plug cap and stick a good plug in there and ground to the block while cranking. If it sparks it’s probably not ignition related.

Waldi

 

+1, or remove one plug and see if it's wet- if it is you probably have an ignition problem.

[Tim D.]

Coil would be my guess. Had similar symptoms a few times and it was generally a coil. 

Tim

[harrytr5]

Rotor arm, if it is the shite pattern one with the rivet then bin it. Dizzy Doc has had his own remanufactured yet again and has then DD stamped on it. There is a few fakes about so watch out. I used to carry these around and rescued a few stranded TR,s but as I have EFI for the last 12 or more years I do not carry them. Well worth carrying one for spares though.

Regards Harry TR5 Nutter

[Andy Moltu]

Coil, condensor or rotor arm whould be the starting point.

There were lots of poor quality rotor arms about a few years ago and many are still in circulation - OK when cold but short out when hot.

Coils again tend to show problems more when hot as they start to fail.

There seem to be any number of junk quality condensors about and whilst they often cause trouble when coldthey can also cause running problems when hot.

Sure it might just be PI related.  but unless the hot running or (non-running) issue is accompanied by a screaming fuel pump it's unlikely to stop the car. Pull out an injector and see if it injects when you crank it over:if so you can pretty well exclude the PI as the cause. A split diaphragm can cause a car to not start when hot but usually has assosciated atrocious fuel consumption as it makes the car run very rich.  Blocked injectors end to cause one cylinder not to fire but don't stop the car.

Historically the Lucas PI was blamed by mechanics back in the day for all sorts of ills, largely out of ignorance and unfamiliarity and they would meddle with it and royally screw it up when it is basically crude and reliable.

 

[TR674]

Thanks all. When I think about it again, I'm heading in the electrical problem direction. As fuel starvation would be a bit of coughing and farting before dying a slow death. This is more of an instant death.

Andy, I experienced the split diaphragm a few years ago. Used 1/4 of a tank for around 10km journey............plus the stink of rich exhaust.

The coil, condenser and rotor arm haven't been replaced under my watch since I bought the car 22 years ago, though mileage has been very low. I'll start there.

[Andy Moltu]

A good coil lasts 20+ years. Mine died on the Ile De Re after 25 years. Always carry a spare in the boot but took some finding after all that time!

We held a brief ceremony in it's honour and tossed it in the bin!

[FatJon]

The symptoms fit a coil problem. I have experienced a couple that died very suddenly when hot and recovered when they cooled. As you said, fuel starvation is usually preceded by some coughing, popping and farting rather than a dead stop.

[Casar66]

Well, now something complete different, do you use a lead substitute after/before refueling? If so that may be of your interest:

 

 

[TR674]

Hi Casar66, no not inertia fuse as the fuel pump stills hums away to a silent motor. 

[Casar66]

it was not the inertia switch, the cause of the funny behaviour - similar to yours - was something total stupid. Go to the last page. If you use a lead-substitute or another extra stuff for the fuel. Check the tank!

[TR674]

Replaced like for like. Took her for a spin on a warm autumn day (30C) and then let it idle in the driveway for 15min or so. Temp started to creep over 1/2.

Motor nice and warm and no cut outs. Did a few stop/starts and no sign of anything dodgy. Also ran noticeably smoother thru acceleration.

Thanks for the assistance, I was on my way to fiddling with the fuel system..........that could have gone badly.

 

 

[cp25616]

Glad you have it sorted now, the failing coil caught me out once, car just stopped dead, after 10/15 mins it started again but continued to cut out until replaced. Problem shared is a problem solved.

Alan G

[Mk2 Chopper]

That's great news and thanks for updating the thread. 

Mine went very near a petrol station, as I didn't have a spare coil, I took it off and submerged it in the fire bucket sand, cooled it fast and enabled me to drive it home. 

Gareth

[Waldi]

23 hours ago, TR674 said:

Replaced like for like.

 

 

Good you solved it.

It somehow feels as if I reward a producer when I’m re-ordering his product after the first one failed. Unless off course when its “old” and it met reasonable the life expectations for this product. 

I have a Bosch blue coil, it must be very old (like 30 years?), and still does its job.

Cheers,
Waldi

[TR674]

Hi Waldi, I'm happy to advertise when the product is fit for purpose. I've owned my TR6 for around 23 years. Don't know how long prior the coil was in service, so seems to have served the car well.

[astontr6]

On 4/24/2022 at 8:40 AM, TR674 said:

Replaced like for like. Took her for a spin on a warm autumn day (30C) and then let it idle in the driveway for 15min or so. Temp started to creep over 1/2.

Motor nice and warm and no cut outs. Did a few stop/starts and no sign of anything dodgy. Also ran noticeably smoother thru acceleration.

Thanks for the assistance, I was on my way to fiddling with the fuel system..........that could have gone badly.

 

 

My view has always been that the coil bolted to the side of the block is not a good idea as it gets cooked every time you use the car and in time will fail. Some seem to last longer than others. My coil is insulated from the block by a two Tufnol blocks to help it keep cool. Even after a long journey the coil is not too hot to touch, after  I fitted the insulating blocks that seems to have cured that problem. I would have re-sited the coil on to the inner wing if I could have found a quality longer HT lead, that one could buy singerly.

Bruce.

[TR674]

Bruce, I thought the same thing as I was bolting the new one in place.  Not a logical spot to locate the coil. I'll be installing some insulation for sure.

Thanks for the info.

[Steves_TR6]

I relocated the coil on my ‘6 whenni installed the 123 distributor and had a silicone ht lead made by Accuspark on ebay as the kvh85 original wasn’t long enough.

its worked fine for several years now so recommended!

[Mike C]

I've mounted my coil on the passenger side of the firewall. Did the same to my V8 Holden. I don't see any point in bolting a coil to a hot engine. Maybe it was easier to manufacture the engine that way originally but it doesn't make sense if you like your coils cool.

[TR674]

Hi Mike, how did you solve the long coil lead back to the firewall?

I was thinking about making a stand-off bracket to get the coil further away from the block.