A broken vacuum fitting certainly won't help your starting or running. I have no idea what connecting in that top fitting would do, except maybe to increase control pressure, which would lean the mixture in high vacuum situations, like coasting. Where does it connect to the vacuum system?

Another thing to check is to put your Mityvac on all the fittings of the WUR. They should hold vacuum briefly and then slowly lose it. If it's a dead leak, then you need to fix it because not only do you have a vacuum loss, you're not getting any enrichment when you need it.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe