[CompClassics]

427 = two pumps running at the same time from the same power source, only problem is when one pump shorts to ground and fails (blowing fuse) both pumps fail, even the good one! There was no mechanical pump on the 427 Cobra.

289 street = one mechanical pump.

289 race = one mechanical pump for normal (main) fuel supply, one electrical pump to act as a booster when switching to the secondary (reserve ) fuel supply via the changeover valve located in front of the drivers seat. The mechanical pump will still draw fuel through the electric pump when the electric pump is not activated. The electric pump is only used as a booster pump.