Stage 1 V8 starts,runs for 15min then dies..every time

Ant109 · May 27, 2020

Hi gents, looking for some insight here for my '82 Stage 1 V8 (3.5 with the twin SU carbs)
Basically she starts fine from cold, then runs and drives fine after warming for 5 min or so, but then after about 15 mins of driving looses all power and stutters to a halt.
Then turns over but doesn't start. After ~10 min sitting there twiddling my thumbs she starts fine and runs again and I get home as fast as I can before it happens again!

This exact sequence happens every drive.

What should be my first line of investigation?

Blackburn · May 27, 2020

Check where the fuel line is located sounds like fuel is evaporating in the fuel pipe.
do you have a mechanical fuel pump or electric?
Is the tank full as could also be debris in fuel tank blocking fuel pick up not sure it would do that exactly to a time frame

wireman · May 27, 2020

Does it run if you squirt fuel into the carb (when its broken down) If not its possibly not fuel. Is it points or electronic ignition? If its points it could be your coil has had it, feel it, if its very hot ( too hot to touch) then that could be it. If you have electronic ignition it could be the ignition amplifier (either a small black box on the side of the dizzy or a remote unit attached to the wing). These are 'non serviceable' as far as I know, so replacement is the only solution there.

wireman · May 27, 2020

Also check your rotor arm? Is it a genuine item? The brass strip can come loose on cheaper versions losing connection, then when you've stopped, it can 'reset' itself then you drive a bit more 'til it moves again.

Colthebrummie · May 27, 2020

On the old ignition points set up, the condenser can cause intermittent problems. But it sounds like the ignition coil to me.

Co,

Shippers · May 27, 2020

Is it the original engine and dizzy and carbs?...had a problem with V8 in my 101 in tank pump kept sucking up a leaf floating around in tank that got in there while lying under tree for 15yrs...also last week stripped carbs down due to difficult to start at the same time put dmm on coil to check as I touched it this cable fell off spade still on coil wire still firmly attatched to blue part been like that for months since I fitted electronic dizzy...

JJKM · May 28, 2020

I'd be looking at fuel first because it'll be easy to rule out. As wireman said, have some fuel on hand for when it breaks down and then quickly fill the carbs manually (a syringe type thing is useful). If it starts, it's a fuel evaporation issue. You'll need to know how to easily and quickly get the tops of your carbs off - if it takes you too long, you may misdiagnose the issue.

Once you've done that, turn your attention to electrical parts, starting with the coil. Do you have a spare or a friendly person to lend you one?

Kev12 · May 28, 2020

Another vote for coil, cutting out when hot is a common failure mode

Ant109 · May 28, 2020

Thanks for suggestions all. I will check fuel into carbs when it cuts out and check coil if not. Will let you know how I get on.

kermit_rr · May 28, 2020

Kev12 said:
Another vote for coil, cutting out when hot is a common failure mode

what he said
see if the coil is hot when it stops, quick and easy, just don't burn your fingers

Mark Frewin · May 28, 2020

Could it be blocked vent/breather pipe on fuel tank, if not fuel filter /pump.( Drive it with the fuel cap loose )

Bobsticle · May 28, 2020

I’d say the fuel tank breather is blocked but I’m rubbish at mechanics so it’s the only thing I could check without it costing me any money.

tottot · May 28, 2020

Another vote for hot coil check.

wireman · Jun 4, 2020

Did you get this sorted?

Stage 1 V8 starts,runs for 15min then dies..every time

Ant109

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Blackburn

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wireman

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wireman

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Colthebrummie

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Shippers

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JJKM

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Kev12

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Ant109

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kermit_rr

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Mark Frewin

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Bobsticle

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tottot

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wireman

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