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GT6 won't start


Bruce_the_GT6
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I have a GT6 Mk2 with CD150S carbs fitted. The engine has been running, bug after a few weeks now will not start.

 

Symptoms:

 

1. Carbs flooding

2. Plugs getting very wet

 

The fuel pump is original fit and has been running correctly. I've fitted an in-line fuel filter which appears excessively full.

 

Looking now for best approach forwards, my thoughts currently:

 

1. Buy a fuel pump kit from James Paddocks and rebuild

2. Switch to electronic fuel pump - if so which is best?

 

Thanks

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If the engine wont start, but is flooding, then I would suspect the problem lies with the ignition.

 

Once you are confident that you are getting good sparks at the right time, start looking at fuelling.

The spark plugs have been checked, as has the distributor cap and rotor arm. My friend is a mechanic and is very convinced it's fuel pump. A tap on the pump with a hammer meant the car splutter to life temporarily before flooding again.

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Tapping the pump is a trick with SU electric fuel pumps - but a GT6 should have a mechanical fuel pump driven off the camshaft and located on the side of the engine.

So I would also suggest you look at the ignition first.

 

Following this, take the air filters off , and you should be able to see if excessive fuel is getting into the engine when you crank the engine. That would then lead you to problems with needle valves and float chambers. But, as Kevin says, start with the ignition.

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Ignition has been checked and all is sparking correctly.

 

Considered the float chambers and needle valve - gave them a tap to see if this freed them up if sticky. Tried to start car but no change.

 

Fuel pump was tapped by hammer, this appeared to temporarily fix the problem as the car nearly fired, hence being confident the problem is likely a sticky fuel pump.

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I have a GT6 Mk2 with CD150S carbs fitted. The engine has been running, bug after a few weeks now will not start.

 

Symptoms:

 

1. Carbs flooding

2. Plugs getting very wet

 

The fuel pump is original fit and has been running correctly. I've fitted an in-line fuel filter which appears excessively full.

 

 

 

 

 

 

I would go with the others on here there is something not right with the ignition system, if you SPECIFICALLY have wet plugs, then its not firing... if you still have points set up then I would look to the points and clean the faces off first...

Has it been stood a while?

 

Having said that I had a problem with my GT6 Mk2 after it had sat idle for six months in that the pump had stopped pumping fuel (never done it before after a long lay up) but appeared to be still working, it's mechanical pump as others have said... banging it ( shouldn't !) won't help !

 

You should have a mechanical lever under the pump,take off the outlet pipe at the pump... pump that lever up and down until it feels "harder" and you can see fuel coming out of the outlet, reconnect pipe and try again.

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couple of thoughts ,

 

check the coil ( ballasted ) has a feed when your ign switch is cranking and when in running positions. as coil has two feeds 

 

if balasted make sure you have a 1.5 ohm coil

 if not ballasted its a 3 ohm coil.

check polarity of coil  ,  is dizzy on the correct coil terminal ???

 

check small braided lead that earthes the dizzy moving plate.

check no green stuff in the coil header or cap connectors

 

dont have plugs with an R suffix in the code

 

if you have messed with the fuel lines it most likely there are floating slivers of rubber in the back of the float needle valve and its suply lines

 

do your strombergs have a starting valve with a link pipe  or 'thames barrier ' type of choke  ????

 

make sure no gaskets are covering any of the front face ports in the carbs.

 

it pretty unlikley a mech pump will over produe pressure it only relies on the internal diaphragm spring.

 

with an open fuel line at idle it should produce a decent squirt and top up a 1/2 pint jug in 'about' 30 seconds idling.

 

wet plugs , agree with a weak or no  spark.     

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  • 3 weeks later...

Just as an update - he's now starting. There was a combination of issues:

 

Fuel pump stuck open - we reconditioned the pump.

This then cause flooding only on the rear carb, likely caused by excess fuel pressure - so fitted fuel pressure regulator.

Still wouldn't start - every time the distributor cap was taken off and replaced we spluttered to life momentarily.

Changed the distributor cap, not change, then condenser still no go. Then noticed the condenser was pressing on the points. Moved this around and regapped the points - fired on the key.

 

Many thanks for the help given. Now he's ready for his first MOT in 29 years.

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