Son has a 1998 Bonneville which has sat for about 4 years,decided would like to use it again and we can't get it started.Added some fresh fuel to the tank but no go.Put car on blocks crawled under and unhooked inline filter to check for flow but nothing,(wife turned on key) checked for power going back to plug,nothing.(Will check again tomorrow not sure if I had a good test light ground)Just wondering if I apply power using my booster pack using grey and a black wire in plug going to pump can I test to see if pump will run?

Was the vehicle ok, before it went to sleep?

First turn key to on, not crank, and observe SECURITY light in cluster,,,,should come on for 3-5 seconds and then go out......if it doesn't, you have a PassKey problem....

cycle key to on, then off for 5 seconds....do this several times to build up fuel pressure.....have a rag handy.......remove cap from schraeder valve on fuel rail, cover the valve with rag while depressing plunger....should have a good squirt of fuel....if none/trickle, you know it'* fuel pump or circuit,,,,,of course if you have a fuel gage, you should use it....with it attached and after cycling the key several times, should get well in excess of 40 psi....

Or, easiest thing to do, is get a can of carb cleaner, and spray into the intake while cranking the vehicle.....if it starts and runs as long as you spray, then you know it'* a fuel delivery problem........

Next put your hand on the F/P relay, and feel if it clicks when you turn key to the crank position.......if it doesn't, try swapping a relay......if still no click, then have to check for power on circuit #465 with key in crank position and circuit #451 for a good ground....you check this at the I/P junction block, where the f/p relay is located...remove relay to do test.....while there you can verify your fuel pump fuse is ok, by checking Circuit # 839, should be hot with key in "on" position....

If ok thus far, disconnect the harness to the tank....attach test light to the harness half, NOT going to the tank.....probe terminal "C"(grey wire), and other end of test light to a good ground......have someone turn key to "on".....light should come on for 2 seconds and go out.....crank vehicle and light should be on steady......If it doesn't open circuit in #120.....

Now verify ground........ attach end of test light that was grounded to terminal "A" (black wire), and do same test again....if no light, bad ground....

If all the tests check out, it is fuel pump.......

if you are doing this yourself, I suggest soaking the strap bolts with PB Blaster, and give it time to soak in, and then spray again just before removal ....Also, be VERY CAREFUL when removing the fuel lines, otherwise you will be replacing more than just the pump.....sometimes removing the plastic lines from the metal ones out of the tank are a bitch.....dirt gets into the plastic connectors making it hard to depress them to release the lines and then pull off......and sometimes when you struggle with this, if those lines out of the tank are rusted/weak, they will break/leak, and then you have to get the housing assembly instead of just a pump.......this job can be a real head ache if everything is rusted up under there(especially if those strap bolts break the welds and just spin).....so maybe a shop would the best solution......

And yes, you can apply a booster to the correct circuit to the fuel pump....pos to"C" and neg to "A"...

Thank You so much for your excellent reply,going to have a look at it again today just wishing it was summer I'm located in Sask; Canada bit cool at the moment.When I try to give it power is A the ground 2 over from the grey,when I was testing D is also a Ground is that correct?

If I remember right, "C", grey, is the power from the relay....."A" is the ground for the fuel pump......."B", purple(I think), is power for the level sensor, and "D", black or black with white stripe, is the ground for the level sensor....if two are black the thicker one should be "A" for the fuel pump ground....

Thank'* so much Tech II for all your help,put booster power directly to pump got one little click sure pump is done.Checked plug feeding pump all is good.Just wondering i'm worried fuel gauge migth not be working added about 25 liters to tank don't think gauge moved,do you think it would be a good idea to replace complete pump assembly,is there anyway to bench test fuel level sensor?Going to call today for estimates because don't have a lift.Thank You again.

Those senders often have issues. Nearly four gallons should have moved the needle. When I did my fuel pump in my `97 LeSabre I had to watch my money so I didn't replace the sender even though it had issues. While you're getting it done it'* worth the extra unless you are good at setting the trip odometer and watching it for ~300 miles to come around for fill ups.

IF YOU APPLIED POWER CORRECTLY, you should have heard a steady hum from the fuel pump while connected........

As for level sensor, all you need to do when you remove the assembly, is attach an ohm meter, to terminals B and D of the harness and then manually move the level sensor.......I forgot what year they changed the readings........

On the old ones it was 0-40 ohms,,,,,,the newer ones were 40-240 ohms.......

Depending on which one you have, "E" with the float down, should be 0 or 40 ohms.....1/2 should be 20 or 140 ohms.....and with the float up at Full, should read 40 or 240 ohms.......but I think your'* is the 0-40 ohm range...

412.00 Candian sold as Napa brand.

Can order from the US for around 135.00
Just wondering how these 2 pumps can be so different on the top but both be direct replacements,have never changed before so don't know what original looks like.

Merged your threads together to prevent confusion.

OK thank you.