jkann1

Well this is what I got.. my fuel pump quit working I replaced the sending unit and fuel pump.. and fuel pump relay.. all I get is it shows a full tank..( its not ).. I check for voltage and I get 11.6 volts at the pump connection.. but when I plug up the pump and test It .. nothing I lost voltage, now I can put 12 volts to the pump direct it works.. checked the sending units ohm there good.. Need help driving me nuts.. anything.. Thanks for your time

pcolt94

Did you have to do any wiring and could there be an error?

Troubleshoot each problem separately. Are you getting 12 volts to the pump for 2 seconds when the key is turned to ON?

High resistance on the sending unit will indicate an indication toward full. A low resistance will make the fuel gauge read a low indication (resistance range is about 10 to 120 ohms). Sounds like the sending unit is not connected.

Almost sounds like there is an open ground for both units. Make sure there is a ground connection to the connector (got to pull it out and look and test).

whalepirot

Tom400CFI

Sounds like a classic case of a poor connection or bad wire; your tests for voltage and continuity are good...when there is no load on the circuit. I suspect a bad ground, since both the pump and the sending unit aren't working.

jkann1

Thanks..... I agree its a open ground but where.. where can I start if there is a start.. thanks for your time

whalepirot

get a solid ground to the tank, and the pump assy. See if the pump runs. the tank may well be grounded, but when trouble arises, I have learned to look first, where work was performed.

Hot Rod Roy

This is a confusing statement.

Are you having trouble with the pump not running, or are you having trouble with the fuel gauge?

First: you need a FSM (Factory Service/Shop Manual)!
Second: you need to fill in your personal information page so we can figure out what year car you're working on. I checked your previous posts and am guessing this is an '84. (That's the hard way)
Third: the fuel pump and the fuel gauge have separate grounds, so your description of the problem is even more confusing!

Please tell us what color wire you are testing.
Yellow is fuel pump 12 v. supply.
Pink is fuel gauge wire to the digital diplay.
Black is fuel gauge ground.
(If my '84 FSM is accurate)

jkann1

Well I don't know about the gage yet... I can't get the pump going like I said I have 11 volts at the plug that you plug into the fuel pump but once plugged in volts are gone pump don't come on... now I have 3 pumps because I thought it was a bad pump.. wrong I put voltage straight to the pump it works.. all 3 work.. I think there is a open ground some where but where.. the car ran great then went drive it and nothing was not getting any gas.. There you have it.. any help is appreciated...Thanks for your time

jkann1

Its a 84 corvette and your color are right .. but yellow is beige and the volts are the... Thanks for your time

antfarmer2

Do you hear it run for two seconds when you key on without starting?

jkann1

No, I didn't hear nothing with key on... but the pump work.. Thanks for your time

Hot Rod Roy

You have a bad connection in the 12 v. supply circuit for the fuel pump. Maybe corrosion in a connector, a bad FP relay, a bad Oil Pressure switch, or a bad FP fuse.

Plug in your FP, then connect 12 v. to pin G in your ALDL connector, and your FP should run.

If the pump doesn't run, what is the voltage on the little test points in the top of your FP fuse?

Let's do one test at a time, so we don't get confused. Do this test and report back to us.

(The ALDL connector is at the bottom of your dashboard, near the steering column.)

Hot Rod Roy

I think that's good news. Does "didn't hear nothing" mean that you did hear something?

The FP in my '84 is super quiet. I cannot hear it run, but my car runs just fine!

If you have the FP working, can you start the car? Where are you located?

jkann1

Tried that and the pump didn't come on...

jkann1

I know what your saying you turn the key I could hear FP... I don't hear that anymore.. I'm in Tenn.. Thanks

whalepirot

How did you run the pump? On the bench?

Does it run from the normal 12vdc connection IF you ground it out of the tank? I'm wondering if you insulated the path to ground of the mounting bolts to the tank, with some kind of sealant.

jkann1

Yea I check the pump from the bench.. it runs good, I ran a ground wire from the sending unit/pump to the tank.. again nothing, is that what your suggesting. I'm confused.. Thanks for your time

whalepirot

Ok, sorry.

U said there was 11vdc at the pump connector, at the tank.

If it won't run when you ground the assembly, maybe the ground wire, in that assembly, to the pump is detached or broken.

Do you have an ohmmeter and know how to use it? IIRC, the ground path is frame>tank?pump assy bolts>assembly>pump/sender; all need continuity (close to 0 ohms).

jkann1

I tried testing it so many ways.. I think I check that I didn't get any reading at all.. I check the sending unit and it checks ok I got a reading but don't remember it.. I check it from the ground plug from the car not the FP assembly I went from the ground on the car plug to the tank... no reading it be a open ground but where...Thanks for your time

antfarmer2

Does that year have a fuel pump relay?