I call BS on wire size!

[SquareRoot]

Putting ep 381 in-tank pumps in and everyone says to use a minimum "14 guage" wire for the supply voltage. Fair enough. But what confuses me is the factory wiring from the pump to the weatherpack connector (inside the tank) is 18 (16 at best) guage.

I've always assumed that the smallest wire in a circuit is the weakest link. Isn't that how fusible links work?

Can someone "enlighten" me?

 

[Blue Ox]

Wire size in a DC circuit has to do with circuit length. So the short bit of 18ga is probably enough to make it from the connection thru the pump and to the ground (which I @$$ume is the tank itself) without overloading that portion if the circuit.

 

[Itali83]

Yeah, I agree. Size needs to increase with length. Still think it’s cheesy for the pump to have that small of wire attached to it but I’d run bigger wire from there to the power source for sure.

Ben

 

[SquareRoot]

So essentially, it's like putting a fusible link inside the fuel tank. Unless, that small guage of wire can carry the required amperage and the likelihood of a short happening inside the tank is next to zero?

 

[Frankenchevy]

Amp draw would need to run away pretty good to fry a 8” length of 16ga wire. That circuit should have a 10amp or so fuse. That’s your limiting conductor.

Not having anything to chaff on certainly helps as well.

 

[Doppleganger]

There was an article in Car and Driver about 15-20 yrs ago interviewing a now retired engineer for Bosch. He said that factory wiring is on average 1 to 1 1/2 gauge sizes below where it should be due to cost cutting (bean counters). I dont doubt that figure a bit.

 

[Ellie Niner]

The last fuel pump I replaced on my 1991 Lumina overheated the wiring in the tank, mostly discoloring the plug that went into the pump. I do question the choice to put 16-18 gauge wiring in the fuel tank... but I've never heard of a vehicle fire related to an in tank pump (unless it's the movies, then everything explodes).

And yeah. Manufacturers always skimp on wiring, so you know that what's there is the bare minimum to make a circuit function (mostly) acceptably. GM also tends to have fairly high voltage regulator setpoints to help compensate for the gimpy wiring... my truck drops about 2.5 volts on the headlight circuit.

 

[SquareRoot]

UPDATE:

Response from Edelbrock engineering:

" The wire coming out of the fuel pump is larger then the wire inside the fuel pump..... it's just it's connection point.

You FEED it a larger gauge wire, do to voltage drops smaller FEED wire would cause. "

Blue Ox- you were correct.

This makes sense to me. It mad eme think of the utility electrical grid and how the wire diameter gets progressively smaller from the power station to the 120v toaster oven.

The windings inside the pump motor are actually very small and thus the "weak link" in the circuit. That's what you actually fuse the circuit for, not the 14 gauge+ feeder wire. Correct me if I've gone astray.