Reconnected the ground wire in the engine bay, sanded it and everything, cant find one by my parking break. I tryed testing the pump with a small car battery with the positive end and it didnt hum so im still lost. How do i test iv im getting 12v to the connector? As of right now i have my tank dropped and the fuel pump assembly out too.
What year is your Jeep ? Mine is a 91 and the ground wire was mounted at the dash on the mounting bolt on the dash. I feel you on this one, it took me a month to figure out I had accidentally disconnected the ground wire. I am getting to be an expert on that damn 4.0
Yes a separate battery, and no i did not, i heard that it was not necessary.
If you were to hook a light bulb to the positive on one battery and the negative of another, it will not work and that is effectively what gou are doing to test your new pump. If you want to test the pump, it needs to be grounded to the same battery to complete the circuit...
If you just ran a positive wire from different battery, and you didn't run a negative wire from the same battery the fuel pump will not work. You need to run both positive and negative from the same battery in order for it to work.
Will doing this create a spark? I am dealing with a lot of gas.
IF you are worried about sparks setting off gas fumes, run 5' of wire to the battery set 5' feet away (or whatever distance you feel is safe) and do it outside. Get a good connection down in the plug and then attach or make contact with the battery so any sparks will be well away from anything flammable and you can remove power as soon as you hear the pump come on.