Hi everyone. I've got a tech question for you... My neighbor has installed a relay for his fuel pump (on a vw bus, making the advice suspect already). The relay's switching power (86) is hooked to the hot wire coming out of the distributor. The idea being if he was in an accident or other calamity, when the engine stops, the relay would be de-energized, and the fuel pump will automatically stop too. He read it was a good idea. What do you guys think about this?
Is the wire supplying voltage only hot when the distributor is turning? If so,then the relay would release when the distributor stops.
There's a couple of ways to do this. Get a pressure switch that connects to oil pressure , when there's pressure the switch is closed and supplies power to fuel pump. There's a device that ford used on there electric fuel pump circuits. If there was a collision this device shuts off power to pump. Also in a roll over it also disconnected the pump. I can not find my information on them as my old computer crashed. Maybe a hamb'r has the part number.
Fuel pump relay is a little different. Yes, it is a good idea for safety. Most guys will use a stock VW fuel pump relay (like what's used on older Rabbit or Golf etc). It has the usual 4-prong setup like a universal relay (2 to energize the relay, 2 for the contacts) but also has a 5th wire that is a reference from the neg side of the coil...used to shut off the relay when engine stalls. Sent from my iPhone using The H.A.M.B. mobile app
Chevy Vega, Pontiac Astre had an oil pressure referenced electric fuel pump. To save that sorry motor that they came with. Got real good at those POS cars when I worked at a Pontiac dealership. Could go to work in the morning change an engine and then go to lunch.
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