205/309 have an in-tank pump, all the 405's i've seen have an external one.
it's easy to test the pump - give it +12v and ground directly to the terminals and check if it works ok.
if it does, then trace it back, find wires 76/76A and M76 and check/replace the relay those wires are coming from.
it would help if you would describe when does it not work or stops working and springs back to life etc.
hope this helps

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