Outer Limits 4x4 Board

Gday,

Just wondering whats involved to wire up an electric fuel pump (maybe two). Where should I wire them to in my sierra . Note that there is no simple harness to join up to, because an EFi engine is replacing a carbies one. Any suggestions. Ive heard about the ignition, how should I go about that?

Thanks

In it's simplest form, you want the electric fuel pump to have power whenever your ignition is on. The coil may be a convenient spot from which to switch your pump. Be aware of ballast resistors and current draw - a relay is probably a good idea.

Ideally, you should include some trickery to ensure the pump only runs when the engine is running. In the event of an accident, the engine could stall with the ignition on - you don't really want fuel being pumped out of a ruptured fuel line. Of course, you need to ensure you have fuel pressure to start with, which could complicate matters. I presume there's commercial "safety relays" to deal with this, but I don't know. I once designed a circuit for this, but never built it - I rolled the car before I "got around to it."

Good luck,

Scott

NJ SWB wrote:I presume there's commercial "safety relays" to deal with this

Called a tachometric relay. Available from most aftermarket EFI mobs like Haltech etc. They're a CAMS requirement for EFI cars (or at least cars must have that functionallity, whether internal to the ECU or via a tachometric relay), so should be easy enough to track down.

I believe gas systems use a similar relay? It would probably be a cheaper option than buying aftermarket EFI relays.

BTW make sure you install one- otherwise if the worse happens you could have fuel pouring out everywhere in an accident.