It's very important to have an in-line fuel filter on the feed 
side of any aftermarket electric fuel pump...some folks let the 
pump be the filter and install the bugger between the pump and 
carb...they never need to change that $2 filter -- it's always 
clean...and then one day...tjuh, tjuh, tjuh, tjuh, tjuh...new 
pump. And I gotta agree -- the tanks get mighty scungy after a 
sittin' spell. They will even rust through if neglected long 
enough. The whole fuel system isn't really complicated, but can 
be dangerous if not examined regularly. One hose can come loose, 
fill the starter and you smell the gas, plop in the seat, turn 
the key...boom...red lights and sirens. Never start an 850 if you 
smell fuel! Also, check to see that the hose in the fender is 
sound and not chafing where it passes through the body into the 
engine compartment...and over that hot exhaust. We 850 guys 
endure enough "foomp" comments without becoming an anecdote.

Dave
'72 850 Spider named 'Lilly'
Portland, Oregon