Fuel pump wire gauge

What's the best gauge wire to use for the fuel pump?
Thanks

depending on the fuel pump and the length of wire, i normally run 12 gauge wire.

What is the rated ampacity of the pump? 12g wire is good up to 20amps and 10g is good up to 30amps. If it is a long distance between battery and pump it's better to go up one size.

holley black and about 4ft of wire.

black only draws 4 amps, recommended fuse is 7.5, 16 gauge will work but i would use 14 and solder the connections

If the fuel pump is in the rear of the car, he best way to do it is to use a relay. That way you have the shortest wire possible feeding power to the pump.

10 gauge on something that important. Going to a relay of course.

What toggle for the 12ga and the 10ga?

BigDave65 wrote: best way to do it is to use a relay.

As "BidDave" wrote, use a relay. As to the switch wires they can be small, 14 or 16 gauge. The heavy wire 10 or 12 gauge will travel to the relay from the fused or circuit breaker protected wire from the battery or the battery lug of the battery switch and from the relay to the pump.

Dave.

I like relays but on small amperage loads like the black pump i feel the relay is just one more electrical devise to fail. Relays are a must for loads to large for a regular switch. If t connection only has 4 feet of wire is the relay required?

Here ya go
http://oldfuelinjection.com/?p=8

What does a relay do, anyway?
Thank ya!

It allows a bigger circuit to be energized by a smaller one.

I'm all about relays and stuff but on a small pump like that as long as the wiring and the switch are of sufficient size to handle the load a relay is not really needed. Pay more attention to the connections and stuff, butt connectors/scotchlocks etc aint good. I like to solder and heat shrink everything , if you need a connector I like the weatherpac stuff.

Understood, thanks alot.
Thanks again

cooter wrote:I like relays but on small amperage loads like the black pump i feel the relay is just one more electrical devise to fail. Relays are a must for loads to large for a regular switch. If t connection only has 4 feet of wire is the relay required?

Cooter;
An electrical component's worse enemy is heat. As the amperage nears or falls below the required amperage to operate a given electrical device, that electrical device will overheat and in time fail. Even though a switch and wiring seem appropriate, at each connection amperage will drop. The less the quality of the connection, the more the drop in amperage. My bet, upgrade to a larger wire, incorporate a relay rated above the required amperage, use a quality switch to power the relay switching event and solder ALL connections! As to the four (4) feet of wire, is the fuel pump sitting in his lap?

tconnection wrote:What does a relay do, anyway?
Thank ya!

Tconnection;
Think of a relay as a starter solenoid. Their the same only rated differently. A relay allows switching of a higher amperage requirement with a low amperage switch (supply). Larger wiring capable of carrying higher amperage loads can be switched by a lower amperage rated switch along with smaller gauge wire. All performed within the relay, much safer and more adequate for the power demand.

When we are wiring, we always incorporate a protected relay when amperage demands are above normal. It offers safer wiring, free from heat or/and component failure due to heat. Also when switch locations do not allow for larger wire, relays are a must not only handling the amperage requirements, too the ease of installation of "big wire".

Use a voltage/ohm meter that will check amperage or an automotive amperage gauge that reads low amperage and test each electrical device you intend to incorporate within your project, that's the best way to determine your electrical requirements! An ounce of prevention goes a long way with wiring!



Just my too sense,
Dave.

here is my take on things, the pump is limited to the wiring the pump company uses. the leads are usually very small and running a big wire to it is only as good as the leads in or out of the pump. this being said i like using relays when required but with only 4 amps what advantage is a huge wire or a relay? I am just commenting on this application and nut a full on racing fuel set up. Not disagreeing with larger wiring, just throwing a different angle on it.

cooter I understand your concerns and apologize for being curt. Here's my take once again! The longer the length of wire carrying DC current, the larger diameter or increased number of strands that wire will require to maintain the required amperage. In this case that you mention 4' lengths of "small wire", a larger wire will supply the required amperage to the pump more so than a wire of the same gauge that is installed within the pump. IMO, and given your example, cut the leads of the pump to 1' and install good connectors. Install a larger wire from the pump leads to the supply.

Dave.