Just pulled wiring off fuel pump to test voltage. How much should I be reading during cranking. I tested and got 9v but when all hooked up not a sound from the pump at all.

 

9V is way low. When you turn the ignition to the run pos, you should see around 12.5 before the ECU times out, which is about 2 seconds I think.

 

Everything except on-board computers run on 12V.

Instead of measuring voltage, connect a spare headlamp in place of the pump. If weak or off, there is a malfunction or corrosion or bad contact in connectors, relays...

High impedance voltmeters can show some reading (as 9V) when there is actually no voltage to run a device.

 

This was while cranking. Didn't read anything in on position. Fuse is good. No corrosion visible anywhere. Changed relay under hood. Very stumped.

 

At cranking is fine, as in 'on' will run only a few seconds.
Next is checking corrosion, contacts... for the grounding connections. And try the lamp as load.
Or, connect the in-place/in-tank pump briefly directly to a battery just to confirm it can spin.
If does not spin, pump is kaput.

 

White is + and black being ground ?

 

Hooked it up direct to battery and not even a hum. It's toast I'm guessing.

 

Glad you checked pump as low vdc reading while cranking could be due to typical voltage drop when cranking. Believe you should get good voltage at connector for a few seconds when ign switch first turned on as others mentioned.

Bad pump not good news but better than a big ?

Good luck.

 

Do not test while cranking.

Turn on the key and those wires will come alive for a moment as a priming pump.

Just use a light bulb - put a tail light onto the wires to use as a test light.
LIke a brake light bulb.

Should get full brightness from it.

Make sure the inertia switch is pushed in all the way.
make sure the fuse is good - not tired and worn out.
Check the fuse contacts.
Maybe even replace the fuel pump relay. Those can get tired.

Lastly, fuel pump on its way out will take MORE current and hardly turn.

never run a fuel pump without gasoline going thru it.
Gas is a lube and no gas will burn the pump out.

 

This^^^^

You mentioned putting a good 12 volt source to the pump, but did you supply it with a good ground/earth too? A good ground is crucial to its operation, too.

The pump may have very well gone bad, but it could be from one of the issues mentioned above. A bad fuse, fuel pump relay or wiring (causing low voltage or amperage on hot wire or bad ground) could cause the pump to fail over time.

So, you may have two separate issues going on here.

You mention in your first post that you disconnected the wires from the pump and found 9 volts while cranking engine. Checking with a voltmeter, you should have in the area of 12.0/12.4, and you should also use the brake/head light method, mentioned above, to make sure you are getting enough amperage. Use the ground and hot wire supplied for the pump and see what you get when you first turn on the key (first 2 or 3 seconds), or while cranking. Your temporary light should be bright while preforming this test...if not...you have to keep searching for the problem. And you will burn up your new pump prematurely, if you do not have the correct voltage and amperage.

Good luck,

Brian.