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Discussion Starter #1
My fuel pump will not work in the car but works fine on the bench when hooked directly to my battery. I have 11.7v at the battery and 10.7v at the pump. I ran a wire from the - on the battery to the - on the pump to find out if my ground was bad but it didn't change anything.

Any ideas
Thanks
Dino
 

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Is it mounted a little lower than the tank level?
Make sure it has gasoline on the "in" port.
Always use a 12 gage wire & a fused relay for electric fuel pumps.
 

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Discussion Starter #3
It's not that the pump won't pump, I can't even get it to make a noise anywhere but on the bench. It was working for years them just quit. What would make a drop of 1v from battery to pump?
Thanks
Dino
 

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Originally posted by CanCamaro:
What would make a drop of 1v from battery to pump?
Thanks
Dino
Only thing that would do that is, too thin wire gage on +/- terminals. Do you have a relay, to feed battery voltage directly to the pump? Also, pump might be defective, sometimes those type of parts get affected by the position in which it is mounted, when they start to fail.
 

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Ditto with others' suggestions given. When you install a relay & fuse, a good practice for insuring the power gets to the pump, is to solder the terminals to the wire. A bad crimp will show up at the most inopportune time.

As for losing voltage from the battery post to the pump, every connection from post to terminal to wire, etc., has some resistance. Plus the wire itself, as mentioned, if smaller gauge. Across every connection, a minute amount of voltage is given up. Hence, a volt is lost, usually as heat.

To see the voltage lost in a wire connection, measure from the power source to the end product, ie., pos battery post to the starter armature. You'd be amazed at the voltage drop. Shouldn't be less than 0.4 vdc.

Plus too, the pump may be going south, as in needing repair, brushes, armature turned, bushings, etc., or replaced. It is a DC motor and draws a good amount of current when pumping, especially under pressure.
 

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Discussion Starter #7
It ended up being a bad crimp. It was one of those press together crimps that make a connection of the 2 wires by cutting through the insulation with a blade. The connection was enough to let voltage go through but not current. Just thought I'd let you guys know how I made out. I got it going just in time for a couple inches of snow.LOL O well it'll be ready for next year.
Thanks for all the help

Dino
 
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