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Engine Runs For 10 mins then stops


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Hi Every one

I am a new member and a proud owner of a Triumph Spitfire mk3 1969 that I have only had for a couple of weeks.

But I have a problem, I hope someone can help me out.

The Engine starts first turn of the key with the choke out and when its warmed up it runs fine with no choke after a couple of minutes. It idles nice and revs up instant no splutter. It will stay running on the driveway for along time it doesn't stop but when you get in and drive away it will run nice for 5 to 10 minutes and then it becomes very lumpy  and looses power, it sounds like its only running on 3 or maybe 2 cylinders. I try to rev it but it wont, it just stops!

If you leave it for 5 to ten minutes it will start again and drive off no problem but will stop again after a couple of minutes. Leave it again, and it will start and drive again and this will carry on until I eventually get it home.

Before I bought the car the owner fitted a new fuel pump. I have fuel coming up to the carbs no problem, I checked. 


Things I have changed.

New coil

New HT Leads

If anyone has any ideas please let me know.


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Is your fuel tank able to breathe? Simple test is to remove the filler cap and run your engine on the path to see if the problem recurs. If it doesn't, the cap is sealing the tank so tightly that the fuel pump is fighting a vacuum. Think about what happens if you try to drink from a plastic bottle without letting any air in - it will start to collapse. Good luck!


Steve C

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Sounds like it could be something breaking down with the heat.

Could be the rotor arm (try a new red one from the club shop) there are issues with new lucas ones. I would try this first.

Could be spark plugs. Points and condensor, again issues with new condensors. Accuspark electronic ignition kits are available on ebay for about £30. I have fitted these to my cars and have been very pleased with the results.

If there is petrol in the carb float chambers when it stops then I would say it is a ignition problem.


Hope this helps

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There are some very poor condensers about , and they seem to perform as you describe,


as the fuel system has been disturbed one very common cuprit is slivers of fuel hose get cut off when fitting to the metal pipes, these float about and end up blocking the back , unseen hole in the float needle

gets held there by fuel pressure and the float level drops and you get the 2 3 cly misfire as only one carb is functioning, when you stop the pressure drops the debris works back to the pipe and then off you go again till it returns


take off the float tops remove the valve, clean behind it, pump,

some fuel into jar the cuplrit often then shows itself



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Also another good old fault thats like you have is check the coil is correct polarity

ie the dizzy link goes to the neg coil terminal and the ign feed to the positive

This is for negative earth for older models postivive earth is the opposite

again this can work well for a while , it stops , you get out and faf around , the coil cools and works again well before stoppping again


check also for fuel connections sucking air between pump and tank

again will idle for ever but on demand fails after abfew minutes of load .




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Thanks everybody for your suggestions,

What I can say is its not the breather as I tried it with the fuel cap off.

I think I shall definitely clean the carbs out and change the condenser, I had planned to upgrade to electronic ignition anyway so I may do that.

What ever I do, I shall do 1 at a time and then we will have an answer.

I will let you all know when I have done it.



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Hi - If you are going to change to electronic ignition, just to advise some people have had issues with "Accuspark". There are other options such as "Powerspark" (Yes they are a different company) at the cheaper end, and others such as Aldon (the club supplies) at the better quality end.


In my experience you get what you pay for !



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If you decide to go for Aldon you can save some money. Aldon Ignitor kits are rebadged Pertronix Ignitor ignition kits. Pertronix are the manufacturer based in the USA and I ordered mine from a company called vintage performance in the US, it was about 2/3 of the price of the rebadged Aldon version from the UK (price about the same in dollars for Pertronix as pounds fro Aldon!. Even more amazing was that it was sent out from a warehouse they had in Camberley Surrey UK! I suspect thats where they stock them to sell them on to Aldon for them to re-branding and resale for the UK after they've added on their mark up!

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  • 2 months later...

Is your 2000 in std form or any mods we need tomconsider,

problems like this are not model related and tend to be a gremlin with the basics


does it run perfect then stop or is there any indication its about to cough and die .?



lack of fuel

gaskets / filters obstructing carb front face ports

tank not breathing

fuel hoses sucking air

failed fuel pump

clogged back of the float needle valve

stromberg diaphragm perforated



green corrosion on Ht lead and dizzy cap, coil terminals

coil wired reverse polarity

defective balast wiring if fitted

wrong coil

condenser, rotor and point s

loose wires on point post and earth flexi

electronic ign being fed with too low voltage when balasted coil fitted

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