Fuel pump

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Fuel pump

Postby 1972vegaz28 » Sat Mar 12, 2016 10:43 pm

Hey all. I got my sending unit/fuel pump rebuilt because of the fuel Guage not working. It's always at full. Well, I connected the newly rebuilt pump to the car and moved the float up and down with the key on. No movement of the gauge, and no fuel pump noise..hooked the pump up to a battery and it works. Not so on the car. Any ideas?? Thanks . 1972 vega. Also the fuse for the pump has power
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1972 Chevrolet Vega Hatchback

Re: Fuel pump

Postby cjbiagi » Sat Mar 12, 2016 11:14 pm

Since neither the fuel pump or the gauge is working it sounds like it could be a bad ground. A bad ground would affect both the pump and gauge operation I believe. Otherwise you may need to track back do the oil pressure switch and see if you are getting any voltage at that point
Last edited by cjbiagi on Thu Mar 17, 2016 6:33 am, edited 1 time in total.
Clyde.........75 Monza 2+2
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1975 Chevrolet Monza

Re: Fuel pump

Postby cosvega76 » Sun Mar 13, 2016 9:59 am

Similar to what Clyde said: if you were holding the pickup and moving the float you would have to attact a ground wire to the chassis, as the pickup grounds through the tank. The pump operates only when the engine is cranking (gets power from the "S" terminal of the starter) or when the engine has oil pressure, connecting to power through the oil pressure switch.

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1973 Chevrolet Vega GT

Re: Fuel pump

Postby Monza Harry » Sun Mar 13, 2016 10:32 pm

Here is a pic' of the sending unit/pump from a Monza with the ground lug circled. Harry
Fuel Pump Monza II with Text.jpg
Sorry Black on Black :(
Fuel Pump Monza II with Text.jpg (219.97 KiB) Viewed 526 times
Monza Fuel Pump Electrical hook up.jpg
Here is a Close Up Much Better
Monza Fuel Pump Electrical hook up.jpg (42.14 KiB) Viewed 525 times
I'm not a hoarder I'm a preservationist 78 Monza Spyder (Soon To Be 2+2 with Spoilers)
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1978 Chevrolet Monza 2+2

Re: Fuel pump

Postby 1972vegaz28 » Mon Mar 14, 2016 10:54 pm

I'll have to check the ground, and if that's good maybe go to the switch . Thanks for the tips!
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1972 Chevrolet Vega Hatchback

Re: Fuel pump

Postby monzacoupe » Thu Mar 17, 2016 12:06 am

I had a similar problem when I installed my rebuilt sending unit. It was a loose wire/bad ground. Easy fix. Good luck!

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