positive or negative earth?

[Morrisbear]

i have a fuel pump that came with the car with some spares, its an electronic one without points and it has two terminals on the blue plastic cap, a negative and a positive. but i have read these are for either negative or positive earthed cars, how do i tell what this ones for? dont want to blow fuses! thanks so much

[bmcecosse]

The electronic pumps get a very bad reputation. My advice is to not use it........ But if you feel you must....... I'm guessing that the pump body is isolated from the electronics - so assuming your car is negative earth - connect the -ve terminal to the body of the car, and the +ve terminal to the feed cable.

[simmitc]

There were some electronic pumps that had a bad reputation - but then there is also a batch of conventional pumps with points that failed after rediculously short mileage. I have electronic pumps with 50,000 miles on them and no problems. The unknown is simply wheter you have a good one or a bad one. Of course, a standard one can usually be got going by cleaning the points and hitting the body with a hammer. The electronic ones tend to either run or fail.

Use a multimeter to check for continuity between the metal part of the pump body and the two terminals. If either terminal is joined to the body, then that is the earth of that pump. Check which terminal of your battery goes to earth. If both the pump and the battery are the same earth, then the pump can be used.

[Morrisbear]

Thanks, did as told and turns out it seems to be for either negative or positive as body doesnt seem linked to either. thanks!

[Snadger]

Lots of electrical bits missing off my moggy rebuild, including leads, battery etc but luckily regulator is still there.

Just to go off topic slightly, does anyone know the advantages of a positive earth system apart from originality and being able to wire it up as it was previously?

[bmcecosse]

There is NO advantage. -ve earth was proven to reduce rusting - so that's why it's universally used now. You should start a new thread for new questions.........