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Discussion Starter · #1 ·
I bought a electric fuel pump and put it in wired it to a to the positive side of the coil so that it would come on and off when the key is on .was working fine for a short wile .wasn't sure if it went bad are if something else .desisted to hook directly to battery,it worked just fine . just to make sure i was going to hook to another positive wire didn't work. pump only works when hooked to battery no were else whats going on.
 

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When you go direct to the batt is this both pos & neg? If so you may have a ground issue. You should never run an accessory off of the coil as this limits the available voltage for the ignition. as to any of the other circuits you might choose. make sure that you have a full 12 volts available to the pump. You might consider a relay for your fuel pump. Good Luck
 

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Discussion Starter · #3 ·
blue54 said:
When you go direct to the batt is this both pos & neg? If so you may have a ground issue. You should never run an accessory off of the coil as this limits the available voltage for the ignition. as to any of the other circuits you might choose. make sure that you have a full 12 volts available to the pump. You might consider a relay for your fuel pump. Good Luck
pump is grounded to fire wall it has a good ground just wonderring why pump only workes while hooked to positive post and not any were else.
 

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Coils generally run on 7 volts on the older cars, before electronic ignition.

Plus, it sounds like you were running it directly off of the coil wire without a relay......Lucky you didn't burn up the circuit. A fuel pump needs a circuit of its own a relay is recommended........and they push better than pull, should be mounted back by the gas tank.
 

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About using relays.......A fuel pump or any device that uses a lot of power should be hooked up to a relay. If not, it can overload a wiring harness and burn it up. What a relay does is, it acts as an on/off switch....A small amount of power can switch it on, but the large amount of current to run the pump goes through the relay, not the on/off wire. They can be bought at any parts or electronic store. You need to know what amperage that the pump draws...it should be on a tag on it.
 
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