After upgrading my fuel pump to a bosch I have found that I am getting a small amount of black smoke on fast take off. I am assuming that it is now running a bit rich, however I thought that since I have not changed my FPR, how is this possible? I thought the FPR would keep the fuel flowing at the same rate no matter what pump was on the car? Could it be something else?

Cheers for the help
Mick

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Old Dog

A more powerful fuel pump will usually increase the fuel pressure slightly and cause more fuel to flow past the injectors leading to a slightly richer mixture. Its normal. You could get it tuned out, but its usually only a small increase in the richness of the mixture that its not worth a re-tune.

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RS Liberty - Because WRX's are only good for parts...

Thanks for that. I have my 650cc sitting in a box waiting for that tune.

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Old Dog