Original 550 spyders came with duel Autopulse fuel pumps fitted in the driver’s side cavity underneath the fuse box. The series 500 pumps were manufactured by Walbro Corp in the USA are still readily available second hand today as they were extensively used on trucks and early model American cars. Interestingly enough they were chosen by Porsche for their reliability as the two 6 volt mechanical pumps were joined together using a pair of manifolds which was necessary to overcome fuel inertia in forward and upward acceleration.
These were connected by a fuel line in from the long range fuel tank used in races like 24 hour LeMans and 12 hour Sebring, to the quad cam engine situated behind the driver, to ensure a constant flow was maintained. The pumps often blocked due to dirty fuel, which is why they were positioned next to the driver, so they had easy access for quick repairs. Today, complete sets are highly sought after with the manifolds and banjo screws being a prized find. They are still very unreliable and often the Autopulse fuel pumps connected are only for show and not functional, where a small facet pump fitted to the fuel line work more effectively.