IT’s ALIVE! Starts, runs for 5 seconds and shuts down

Hi guys

Well I am at the end of the line and the end of my rope. I’ve got everything done for the triple SU’s conversion. But the car won’t run. It starts runs for 4 to 5 seconds and then shuts down like I turned the ignition off.

I check the fuel pressure just in case and I have about 2.5 pounds. I also swapped the coil just in case.
The car runs smooth for its very brief time

As I mentioned it shuts down like someone flipped a switch. So I don’t think it’s fuel related, as that usual is a stuttering death…

I do have a Pertronix in the dizzy…

Any thoughts?


I’d swap in a set of points to see if that takes care of it. If you do not have a set of points – in my opinion you should. I see the appeal of electronics but points will often get you home.

After it dies how long do you have to wait until it starts again?

Were you running the Petronix before the carb swap?

As soon as it stops (as it’s stopping) turn off the ign to stop the pump. Take a float cover off and see if it’s about 1/3 to 1/2 full. If it is, it isn’t likely to be staving for fuel.

If nearly empty, you’ve got a bad fuel line choking the flow to a drizzle, too little fuel to keep the engine running or a clogged filter/stainer.

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It needs about 10 minutes

And yes, I had the Pertronix in for quite awhile with no problem

My brother had a Triumph that exhibited similar symptoms. He was complaining to my uncle that it would not keep running so my uncle went over, took off the gas cap and blew (with pressure) into the tank. (He actually pressurized the tank momentarily.) This resolved something in the fuel flow and the car started and ran fine afterwards. I don’t know if there was a bubble in the line, fuel pump priming issue or what.

Don’t blame me if you do this and it does not work.

Just a guess… by-pass the ignition switch.

Just tried that and got the same results… ran fine for a few seconds. Then shuts down

Check that the vent tubes to the float bowls are open. Remove the tube at the top of the float chamber and make sure the air passageway is open. There should be a small round fiber ring with slots in it for air flow.

When that happened to me, it was a ballast resistor problem.


“Prediction is very difficult, especially if it’s about the future.”

Physicist Niels Bohr


The overflow pipes are new, and I have the fiber washers in place between them and the top of the float bowl

But here’s a question. Where is the vent for the tank? I wonder if I’m pulling fuel without a vent, which creates vacuum pressure in the fuel line? Which will stop flow quickly

Easy enough to test that - just remove the cap and see if anything changes.

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My brother tried that. It required pressure to re-establish the fuel flow.

I used to have a Honda cycle that often required mouth to mouth resuscitation. It was kind of embarrassing.

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Does anyone know where the fuel tank vent is?

On mine it’s a tiny hole in the cap, not sure about the later cars. I’m not sure why this would be a new problem for you though.

The latest change was new carbs? If so I’d suspect the fuel check valves/float adjustment.

Hi Erica
The car has been sitting for a couple months, so perhaps a spider or something found a home…

I’m guessing electrical. One time I had the fuel pump power disconnected and started the car and it ran for about 20 seconds before fuel starvation. So I’m not thinking fuel. That it takes about ten minutes before it starts again leads me to believe it’s electrical and something is overheating and killing electricity somewhere, it cools and works. Maybe a failing ignition switch or poor connection there.

Hi all

So I tried a set of points and got nothing different, so I reinstalled the Pertronix.

I also disconnected the fuel rail by the carbs, and ran the fuel hose into a container and pumped about a quart of gas, and did this with the gas cap both on and off, so I’m not thinking it’s fuel supply problem. Pressure was about 2.5 pounds.

I also blew through the fuel rail and got no sense of obstruction. I checked the level of fuel in the float bowls and that seems good. The level was high, if anything.

So… I’m at a loss

Thoughts, suggestions, ideas??

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