Conks out after 2 miles

[Rickety]

The is new 'old' post - see also 'sudden loss of power'.

Problem is this :
Starts ok from cold. Runs a bit 'lumpy' but ok....maybe misfiring a little but still clocks a decent speed on flat. Then after about 2 miles is starts to flounder. loses power and eventually stutters and conks out. Will not start again until cooled down.

I have:

- good spark at each plug
- checked fuel pump - this delvers fine when disconnected (both when cold and wehn hot)
- replaced old carb with new HS2
- replaced (twice) condenser
- set points about 20 times !!

Am losing the will to keep trying...it's been over a month on and off now. Would take it to my local garage but it's more than two miles away and so would have to do it in two stages !!

Any final suggestions before I resort to a tow....

Thanks

Rick

[bmcecosse]

If it has sparks and fuel - it will go..... So something is missing......... There's no short cut - you need to track down what it is........ Are all the connections clean and tight? Maybe it's the coil?? Does it get too hot to touch ? Rotor arm and dizzy cap would be most likely suspects for me - and the low volts wire in the dizzy? Is the 'choke' going OFF ok - not stuck full on?

[tomas.geoghegan]

Dare i say Is it the Ignition coil. same symptoms as i had!!
Tomas

[dalebrignall]

it will be the connections to the coil

[mike.perry]

You have not changed the fuel filler cap for a non vented type?

[kennatt]

try a different coil,

[Rickety]

Thanks for thoughts.

Coil ? If were coil would I still have a spark at each plug when it conks out....which I do. This is what has pushed me down fuel starvation route.

Have double checked all connections - sound. Could replace cap and rotor arm. But - same question re coil. I have spark when it conks out. But it won't start until it cools right down.

Rick

[MarkyB]

There is less resistance to getting a spark in the open air than in the engine, I'd go for a new "high performance" or old stock rotor arm.

[Ratbag]

Carry a can of 'cold start' or whatever it's called over here & spray down the air intake when it stops & see if it will then start - you will then have positively diagnosed (lack of) fuel as the cause.
Remove aftermarket filters, check needle valve/float/chamber etc?

Phil.

[simmitc]

Carry a can of 'cold start' or whatever it's called over here

"Easystart", and that's probably a bit safer than pouring petrol into the carb, but will give the same diagnosis.

[Rickety]

Thanks v much .... a few things to go at and I'll report back in a few days !

Ricik

[Biggles1957]

I had an MG Midget that started doing that and one problem was the fuel cap not lettiong enough air in to the tank, and another was one of those pesky conductive rotor arms.

[JOWETTJAVELIN]

Just a thought. Are all the cooling hoses ok? Maybe one is kinked and not enough water is getting through, but then this wouldn't stall the engine unless it drastically overheated.

[chickenjohn]

Other than the excellent suggestions above, maybe your head gasket has gone between two of the cylinders and if overheating, maybe the vanes in the water pump have eroded so no cooling in the cooling system leading to engine seizure within two miles.
Or rad blocked or thermostat stuck closed.

" Will not start again until cooled down." is the clue!

[Rickety]

New coil fitted at weekend. Initial 'test' looks promising. Only had time to do about 5/6 miles but no trouble. Thanks all for the various suggestions. I suspect that if it is still conks out next time I'm out it could be the head gasket. But fingers crossed.

Rick

[bmcecosse]

[chickenjohn]

It sometimes IS the coil!

[bmcecosse]

Highly unlikely in this case - coils either work, or don't work. Not 'time sensitive' !!

[autolycus]

Have to disagree on this one. I've had two coils, (same batch, same supplier) that overheated, suffered internal insulation breakdown, and "cured themselves" when they cooled down. Why let it happen twice? Because I'd bought two new coils to replace a codged-up ballast resistor system (with relays!), and was carrying one as a spare. And I wanted to get home.

Kevin

[JOWETTJAVELIN]

Coils are odd... seems you either have a good 'un or a duffer (the one on my Allegro is still going strong after 37 years).

What is classed as overheating? On my Minor the other day I touched the coil (replacement Lucas - about 5 years old - yes the old one was at fault but everything wears out eventually) after it had been on a run and the engine idling for a few mins, that was hot to touch and you couldn't touch it for very long. However I suppose this is to be expected if it has to change 12v into many thousands of volts.

So far I have never had any ignition trouble on the 3 classics I have owned and the many, many miles they have covered.

The quality of some modern parts is diabolical as members have pointed out.