Again, thanks for the ideas.

Here is where I am and what I've tried. Looking for QA to make sure my ideas are sound.

I wanted to verify the power going into the fuel pump to satisfy myself that the pump itself is indeed defective. My wife already ordered another "discount" Ebay pump. I think picking up that $213 pump AC Delco pump seems like a smarter idea. Hope I don't regret her buying that other pump. I will bench test the new pump if I don't find another issue before it arrives.

As far as "testing" fuel pump, I believe I can just apply an external 12V source to the pump and it should at least run until the internal regulator cuts it off if hooked up or spin relentlessly if not hooked to fuel pipe on a bench?

I had the idea of climbing under the car and testing fuel pump power supply with a multi-meter at the "power-block plug" that supplies the fuel pump where it comes out right in front of the rear axle through the sheet metal. I have two issues. unless I drop the fuel tank again, I don't know which are the primary power wires for the fuel pump without a wiring diagram. There are like 6-8 wires at that power block. Two should power the pump, two should power gas gauge sender and at least two should be the gas tank pressure sensor, right?

I did check the fuel pump relay by swapping around similar relays with the fuel pump relay and the other circuits still worked when I swapped them around. The good news is there is 12 volts of power at the fuel pump relay every time I turned the ignition ON.

Strangely, when I crawled under car to check the power-block plug for the fuel pump, I was not seeing 12V on any combination. I did see a strange 3.5V reading with one combination...weird. I guess I am in need of a wiring diagram to really put this test at the fuel pump power block plug to rest.

 

Can't you use the old pump to figure out the power circuits? I don't have a schematic myself, but donbrew might be able to scrounge one up.

 

Unfortunately, there is a 8-12" jumper wire assembly that links the rear fuel pump "power block" to the fuel pump, fuel gauge sender, and fuel tank pressure sensor and I can't tell which wires energize which fuel tank item at the fuel pump without dropping the tank again. The wires go into that wire assembly in a bundle and come out on top of the tank where I cant access without dropping it out again. I think I'll wait on that until the new pump arrives as the car will still start after a number of tries as originally described. Still frustrated on this still. I'll be furious if it is indeed a bad new fuel pump...or confused if the pump is not the issue. Hoping it's not a wiring issue.

 

This might help. Note where the ground wire goes(red circle). You may want to check that connection since it's easy to access.

 

Does this help?

 

Donbrew to the rescue again!!! Nice job Don.

 

WOW!!! Those diagrams are AWESOME. Hopefully the 2007 wire colors are the same. :)


I'll jump back there again tonight and check the power outputs at that plug. Armed with a volt meter and this diagram; should yield something very tangible IRT a diagnosis. THANKS. Let ya'll know how it goes.

 

The ones I posted are for 2008, the only difference is it include the SS(LNF) wires, 2007 had no SS.

Colors are the same, just ignore the LNF notations.

 

No update yet, be patient my friends. Between it being 107 daily to being busy at work, I have not been able to get to her yet. I won't forget to report what eventually happens when I get back to checking the circuit and/or popping in a new pump.

 

Status update. Went back under the car to check power at the plug/block that comes out from the sheet-metal above the fuel pump. Bad news is there is only 5 volts at that location. Obviously that's enough power to just allow it to start after a couple tries, but it isn't working as designed.

I also double checked the power at the under-hood fuse block. There is 12V at the fuel pump relay, both the high amp and switch side. Of course the fuse is good too.

I also took the time to jump 12V to the fuel pump at the jumper wire and the fuel pump runs no problem.

I went to the in-car fuse block and took the time to disconnect and reconnect the three wiring blocks located there hoping I'd find a loose connection and the source of the short or low-voltage. I was especially hoping the big red block was the culprit.

Guess I'm hoping for some tips to find where the power is dropping off. I couldn't really check the red wiring block at the interior fuse block because I don't have a wiring diagram. Would be nice to see if the low voltage occurred at that location, assuming the fuel pump power even routes through there.

Thanks, Folks.