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Discussion Starter · #1 ·
What happens if one of the pump jets (including cover, washers, everything) goes missing. It looks like one of them popped itself out and went missing after my last race. Engine was running fine, but later one found a slight fuel leak, at the time had no idea where the fuel was coming from, I still don't know for sure. Was looking for replace everything missing and give it a buzz, just to find out what pump jet size I have, how do you find out, just by measuring the other one I guess ? :irked: Is it size 45 if I have Weber 45s ?
 

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What happens if one of the pump jets (including cover, washers, everything) goes missing. It looks like one of them popped itself out and went missing after my last race. Engine was running fine, but later one found a slight fuel leak, at the time had no idea where the fuel was coming from, I still don't know for sure. Was looking for replace everything missing and give it a buzz, just to find out what pump jet size I have, how do you find out, just by measuring the other one I guess ? :irked: Is it size 45 if I have Weber 45s ?
A missing accelerator pump jet will cause fuel to be pushed out of the tapped hole, especially at full/sudden throttle openings: rather dangerous!

The size is stamped on the jet, so you could unscrew one of the remaining ones and take a close look at it: if your eyes are like mine you'll need a magnifying glass! My Alfetta has Dellorto DHLA40s, and I use 0.50 accelerator pump jets. You can buy new ones in various sizes here, but if the whole thing has gone missing then you'll also need the holder, spring and o-ring (seal) - so maybe best to give them a ring or drop them an email to explain what you want?

Gower and Lee have always been really helpful for carb spares too.

It's just possible that the thread in the carburettor body might be damaged if the jet has worked loose, so try another jet in the hole for the missing one, to check that it's still ok.

By the way, a "Weber 45" has two 45mm diameter throats/throttle plates, and the "45" does not relate to the pump jet size, which is chosen according to the application. Of course, your car might (by coincidence) have 0.45 jets - although Weber 45s on a modified engine that's used for racing might be happier with 0.55 or 0.60 pump jets...
 

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Discussion Starter · #3 ·
Thanks for that Rob, great info. Had a closer look at the culprit and it's not the pump jet missing, but the knob in the middle who popped out. Where could I get one of these puppies please ?

My webers knowledge is certainly getting better!
 

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Thanks for that Rob, great info. Had a closer look at the culprit and it's not the pump jet missing, but the knob in the middle who popped out. Where could I get one of these puppies please ?

My webers knowledge is certainly getting better!
Any decent Weber specialist should be able to supply that screw: I'd suggest you email them the photo, so that there's no misunderstanding about which part you need.
Southern Carburettors
Gower and Lee

Have you tried one of the remaining ones in that position, just to be sure that the thread is ok?
 
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