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Discussion Starter · #1 ·
I recently inherited this Mark 2 and am in the process of fixing a few things, IE the carburetors. At present when I Start up my vehicle it starts up immediately, but the engine races to 4000 rpms and stays there. My carbs do leak petrol, so I will have these rebuilt. No matter what I set the Idle speed at low or high or the petrol volume, it still races. Can anyone help with an idea of why my engine is racing at startup and won’t return to proper idle speed. Is it the Carbs or the fuel pump? If anyone could give me some input I would greatly appreciate the help.
 

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Nothing to do with the fuel pump.

If it's actually racing up to 4000 RPM and staying there, then this is a throttle issue. It must be sticking open. It may not be sticking open a lot (maybe 1/4 throttle) but that would be enough in a no-load situation to rev up that much.

So it's all easy to check. Indeed disconnect the carburettors from the gas pedal and make sure the butterflies are completely closed. Then fire it up.
 

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Discussion Starter · #4 ·
Thanks for the reply. I will check that out.

Nothing to do with the fuel pump.

If it's actually racing up to 4000 RPM and staying there, then this is a throttle issue. It must be sticking open. It may not be sticking open a lot (maybe 1/4 throttle) but that would be enough in a no-load situation to rev up that much.

So it's all easy to check. Indeed disconnect the carburettors from the gas pedal and make sure the butterflies are completely closed. Then fire it up.
Thanks for the reply. I will check that out.
 

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Another problem could be an inlet (vacuum) leak, when someone has adjusted the mixture to compensate. Obviously check for sticking throttles and choke cables (remove air cleaners and have a look at the position of the openings) first though. Sorry for late reply.
 

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Umm, it's a throttle problem. No sort of air or "vacuum" leak is going to make the engine rev at 4000 rpm with a closed throttle. The exact opposite in fact.
 
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