If you mean the idle speed adjustment locking nut, I think that it is a deep 14 or 15 that you will need.
The hand pump can be taken off with a crow's foot wrench connected to an extension and turned with a ratchet.
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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
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