fuel issue on 1972 fastback

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Adz
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Joined: 19th June 2016 - 1:15pm

fuel issue on 1972 fastback

Post by Adz » 19th June 2016 - 1:34pm

Hello, I own a 1972 fastback with a twin carb 1600cc. It has a problem once it gets warm (about 10 min running) that it losses power. It won't go up hills and even has troubles on the flat roads. Once it cools down it is fine again until it heats back up. I thought it might be a fuel issue but after completely cleaning the tank and replacing fuel line there is still no change. My mechanic is scratching his head so any help would be appreciated.
Thanks.
Adz

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Editor
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Joined: 10th October 2004 - 8:52pm
Location: Pensford, Bristol
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Re: fuel issue on 1972 fastback

Post by Editor » 21st June 2016 - 12:31am

Hi Adz, check the choke flaps are opening. If not that's the problem! The wiring to the auto chokes may not be delivering 12V as required, or may themselves be faulty.
Other possible is there's an air leak in the balance pipe system which works ok when the chokes are on but the mixture is too weak once warmed. The 10mm bore rubber joining hoses perish, or even drop off!
I doubt it's a problem with fuel flow itself if it runs initially and accelerates normally while warming up.
There are other reasons, such as running hot, but if you're UK based it probably won't be that! (it's 43 C outside, here in Arizona).
Dave.

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