Fuel Pump: strange part

OK…received exact replacement SU electronic fuel pump to the one I installed about 15+ years ago.

Pretty sure I know the answer to this question, but always pays to check.
See the two photos, below. The new pump has this plastic top on one of the pipes coming out of the body of the pump. The old does not.

Now normally, I’d say that this “black cap” was just there to prevent stuff from getting into the pump before installation. However, it’s not just one of those rubbery, push-on friction caps. It’s hard plastic and slides firmly over the small pipe. And inside the cap, is a stalk that holds down a little metal ball over the opening of the pipe when it’s fitted. Seems like an awfully weird / complex way to cap this pipe for transit/installation.

So, unless I’m mistaken, this hard plastic cap and little metal ball are throwaway items, since the old pump did not have this attached when I took it out.

True ??


'65 XKE 4.2lL OTS

My understanding is that this is a vent valve, designed to allow stray fuel vapors a way of exiting the cap, while preventing stuff from falling back in.

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Just to add to the ‘confusion’, on my V12 pump that I’m currently rebuilding (essentially two SU pumps joined in the center), one end has it the other end doesn’t.

OK…Listened to Michael’s info…and left the cap on the pipe. Installed the pump…it works… and drove it a couple of miles just to make sure all was ok…and so far, so good.
Thanks, Mike.


My buddy is sorting out the engine on his '73 V12 XKE…and he recently got a new SU “double” pump, as you described. I’ll check with him to see what his looks like…