Re: Bench testing my combination fuel pump vacuum question

Posted by calcustom8 On 2009/8/30 16:43:37

I did, actually I have looked at it several times, it gave me the inspiration to tear into mine. Looking it over, the vacuum pump must be a vacuum assist, because for the most part the "big" spring holds the diaphragm in a neutral position. It looks to me that if the engine vacuum is large enough to pull the spring, then the pump would "kick in". I am going to guess that my hypothesis that the pump was meant for full throttle operation is wrong. The pump is meant for when the engine is idle and the vacuum is the strongest. Must be a smooth idle thing.

Thanks,