PontiacBonnevilleClub.com

First of all the bad..the car sat for about 20 months because I am a lazy bonneville owner. Ok. When the car was parked, it started and ran fine.

Fast forward to today, the dead battery was replaced and now it is a cranking no start. I have no fuel pressure at the rail so that is the path that I am currently chasing.

I pulled the access panel in the trunk and I have no voltage on the GREY wire at the fuel pump which should be "FUEL PUMP MOTOR FEED". Both grounds will carry a TEST LIGHT voltage (so they are good? but not tested under heavy load)

For the 2000 SSEi the next stop back on the voltage train is the FUEL PUMP MODULE. There is no voltage on the GREY wire coming out of the MODULE. The grounds here also appear to be good.

Next stop REAR FUSE BLOCK.
I was able to free up the FUSE BLOCK and turn it over. With the key on there is no voltage on the Dark Green/White 12V control wire that is powered by the PCM (PIN 85). The associated ground (black wire pin 86) lights a test light hooked to 12V. Both sides of the 20A Fuel pump fuse light a test light hooked to ground so good fuse and power coming in.

Visual inspection of the PCM in the airbox says no rodent damage/nests are in there.

My next step is to buy some Backprobe Pins and checking for 12V coming out of the PCM on the DRK Green/white Fuel Pump relay control wire with the key on. Its kinda buried in there to so thats a pain.

So before I start down the PCM rabbit hole I wanted to outsource my brain to the internet and make sure there wasnt some big AHA! thing that I am missing in my diagnostic process.

Anybody have anything to add to my frustration??

check the RR wheel well, some wires go there and may be rotted

Thanks for the reply. My next step was going to be to gut the car interior. It has a leak and there has been a lot of rain..maybe one of those wire connections on the floor board is full of the green crusties or something...I will check the wheel well too..

As I mentioned in our conversation, I'm still leaning towards the fuel pump module.

harofreak00 wrote:As I mentioned in our conversation, I'm still leaning towards the fuel pump module.

Would that cause no power to be coming in to the module? There is no voltage coming in or out of that module and the 12V relay signal is missing at the fuse block too. It may also be the module, but I'm not convinced yet. I do appreciate the input though..

I read your original post more thoroughly and can see you're on the right track going through the order of operations. I've not heard of a PCM having an internal fault for the fuel pump relay control, so probably a short or break in that dark green/white control wire. You're on the right track. Have you tried simply jumping the relay?

harofreak00 wrote:I read your original post more thoroughly and can see you're on the right track going through the order of operations. I've not heard of a PCM having an internal fault for the fuel pump relay control, so probably a short or break in that dark green/white control wire. You're on the right track. Have you tried simply jumping the relay?

Not yet. I'm sure how, but I dont have a fused jumper in my diagnostic kit. Im skittish of sending battery voltage down the line if there is a short to ground. That could get interesting really quick..

I am going to gut the interior this weekend ( unfortunately I am deemed an "essential employee" and I am still at work all week). I will report back with more information when I find it.

I appreciate everyone taking the time to read and chime in. It is super frustrating to fail at this especially since I am the root cause...

The car smells terrible inside so I am betting that there is water sitting under the carpet and a wire harness junction might be sitting in it. Or it could be crusty and not allowing voltage to flow.

I did apply 12V through a test light to the green/white wire and the relay clicked. The fuel pump does not come on and there is still no power coming out of the relay on the red wire while the relay is "bypass" tested. I bet here is something super funky going on in there under the carpet...

Dumb question, but you did try swapping the relay with another working one?

the wires in the well ARE for the fuel pump module, i think.

harofreak00 wrote:Dumb question, but you did try swapping the relay with another working one?

yes I did. i didnt change anything for the fuel system.

Update:

It was wet in there...here is some nasty pictures..

that little moisture absorber wasnt pulling his weight LOL
The bad:
I still do NOT have 12V at the relay. I purchased some quliter's T-pins to act as make-shift back probes and I will check for 12V at the PCM as soon as the weather gets better..( we are heading in to several days of rain). In the meantime, does anyone know of any reason why the computer would pull power from that pin? Antitheft strategy? I know there are some "run-time" reasons like loss of feedback from pump and loss of oil pressure that it would pull power...but I think that if the PCM reads RPM=0 it just turns on the pump...

The good:
I'm not sure what changed, but I now HAVE 12V at the OUTPUT of the relay if I give the signal wire 12V with my test light. That power is now showing up at the module and the pump connection itself..the pump still, stubbornly, refuses to run..

It appears that I am chasing multiple demons here..my next step is to test the PCM and make sure that it is giving 12V at that pin when key is on. at that point I guess I replace the PCM..ugh. Then I need to finish diagnosing why the pump doesnt run..

I appreciate everyone who is following along and has added input/ideas. I'm not a mechanic so I'm honestly a bit over my head here.

You could try to run a direct hot wire 12V to the pump and see if the pump turns on, if not then, replace the pump.

AnthonyK wrote:You could try to run a direct hot wire 12V to the pump and see if the pump turns on, if not then, replace the pump.

I could do that but:
1) I don't have a fused jumper. If there is a short to ground or something wonky like that I would feel better about a fused jumper. I need to get out to the parts store and get one..but you know..no school for kids, work, COVID!..I'm behind.

2) That still leaves the lack of 12V control signal from the PCM to the relay.

So I am just choosing to sort that problem out first.

It may end up being 2 separate problems..ie broken wire between PCM and relay AND a bad fuel pump but I am trying to actually diagnose the problem with out just firing the Parts Cannon at it...

I appreciate your input and thanks for commenting!

Totally understand, this virus is really putting a hurt on us. Definitely a good idea for a fused jumper...spark or short, or anything of that nature is obviously not good near fuel or vapors. This has got me wondering though, if the pumps electronics have gone bad, essentially not making a complete circuit would the pcm no longer send 12v signal to the pump ?

There is nothing wrong with hooking 12v (no fuse) directly to the pump to test it. Just bypass the car wiring completely, apply 12v and ground to the pump to verify it works.

harofreak00 wrote:There is nothing wrong with hooking 12v (no fuse) directly to the pump to test it. Just bypass the car wiring completely, apply 12v and ground to the pump to verify it works.

i'm going to get it tested this weekend. If it is bad is this a part that is best purchased new or is a gently used OEM unit an ok substitution?

If you get new, don't get the cheap chinese aftermarket junk. AC Delco or Delphi. I haven't had good luck selling used fuel pumps unless they come directly out of a running car. Sitting on the shelf and drying up usually ends up seizing the motor or bearings.

harofreak00 wrote:If you get new, don't get the cheap chinese aftermarket junk. AC Delco or Delphi. I haven't had good luck selling used fuel pumps unless they come directly out of a running car. Sitting on the shelf and drying up usually ends up seizing the motor or bearings.

I was thinking of getting OEM AC DELCO...as a bonus, that should also fix my fuel level sensor issue..

the assembly is mucho $ - they wanted 500 up here in Canada for oem

96 SSEi wrote:the assembly is mucho $ - they wanted 500 up here in Canada for oem

Rock Auto wants about 220 here in US.. that's still a stinger for a fuel pump..