3.8 Fuel Pump Wiring

I’m making good progress on installing the new fuel pump in my '63 FHC. I have a really basic wiring question about the in tank fuel pump. I ask this question because electrical is my weakest area (out of many weak areas) and I don’t want to accidentally fry a new fuel pump.

The 3.8 fuel pump design has the little plastic box mounted to the front of the boot well where the electrical connection is made coming from the pump. There are a black wire and a white wire coming into the box and one connector is black while the other is white. The old pump had a black and a white wire, which connected up to the corresponding color wire. The new pump, however, has a black and a red wire. Am I correct that red from the pump should go to white? (System is still 12V positive ground) Again, I just don’t want to screw anything up.

Nada? (Y veinte mas)

Don’t think you can screw anything up. If fuel comes out you are good. If not switch the wires around.

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Thank you, Kris. I appreciate it.

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It likely depends on what type of pump you bought. I don’t think an old style points pump cares about the polarity but a new style electronic pump might. Do you know if what you ordered is designated pos or neg?


Pretty sure it was this one from SNGB: SNG Barratt US | Keeping your Jaguar on the road.
Description says can be wired for positive or negative ground vehicles. The reason I say “pretty sure” is because I ordered it a couple years ago when I was more optimistic about how quickly I’d work.

Okay so unless there is some polarity switch that needs to be manually set on it, then it probably doesn’t care. Are there instructions? It seems a little shallower than normal. Does it actually reach down into the sump?

Time sure flies with Jags don’t it?

No instructions that I could find and pretty sure I wouldn’t have lost them. It might be a little shorter than what it replaced, but does reach down in the sump so no problems there.

I might pull it back out to double check for a polarity switch but I didn’t notice one.

I resemble that remark! :grin:

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As someone mentioned, either way should not kill the pump. My 63’ was negative ground and when I installed it with a replacement SNG pump, of course it was backwards. Switched the leads and all good. I no longer have the car, so I cant check. Either way you wil be ok. Jeff S.

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Thanks Jeff. That’s reassuring.

I did this last year. On the new pump the red wire is positive and the black negative. If your car is still positive ground connect the red pump wire to the black harness wire and you should be good.

Thanks, Robert! Exactly what I need. I don’t have fuel in the tank yet and going to be gone for a couple days, but I’ll get things hooked up and test it when I get home on Sunday.

Just to close the loop, Robert gets the prize! Red to black and black to white did the trick. Worked first time.