Join Date: Dec 2001
Location: Belleville, Illinois
Thanked 22 Times in 17 Posts
Re: Mechanical or electric fuel pump?
Leve, you're probably right about the fear of the unknown and electrical stuff, at least in many cases. In my case however, I fully understand the electricals of a fuel pump but still prefer mechanical. Could be that I'm turning into an old fart.
When I think of the components that could cause a failure - a switch, should be at least two, a fuse, several connectors and several feet of wire under the Jeep in the mud and slop, electrical ground, plus the pump (brushes, armature, bearings and the pump itself) - I just feel more comfortable with a mechanical.
The Lucas pumps on the sports cars I mentioned don't whine, they're clickers. They're just like a mechanical pump except that they use a solenoid instead of an eccentric to compress a spring, which pushes on a diaphragm which moves the gas. When the spring is relaxed it closes a set of points which activates the solenoid again. It's about as simple as it can get.
I never took one apart to see why the points would occasionally not complete the circuit, because one never failed hard, but I suspect that it was that the spring sometimes would get stuck. As I recall they would usually fail when the car was parked, so I think that bumping down the road kept them running.