V1 LeoZug's Montana Street Goblin - '05 Cobalt SS donor

[Leo Zugner]

And would the fuel pump need to be all hooked up before it would satisfy all this checks? Meaning it need to fully wire it up to get that 12v read?

 

[Gtstorey]

Be careful putting jumpers in the fuel pump relay slots. If you short them the wrong way you will burn out a trace in the circuit board in the fuse box. You didn't empty your donor fuel tank by jumping the relay did you?

 

[Ross]

Swap the relay with a working one. The AC relay or the Aftercooler pump relay.
Test #2: put your finger on the relay, can you feel it go click when the key it turned on?
It should throw the relay whether the fuel pump is hooked up or not.

 

[Leo Zugner]

Be careful putting jumpers in the fuel pump relay slots. If you short them the wrong way you will burn out a trace in the circuit board in the fuse box. You didn't empty your donor fuel tank by jumping the relay did you?

Ok. Noted. No. We were able to siphon it out.

 

[Leo Zugner]

Swap the relay with a working one. The AC relay or the Aftercooler pump relay.
Test #2: put your finger on the relay, can you feel it go click when the key it turned on?
It should throw the relay whether the fuel pump is hooked up or not.

Ok. I’ll try that.

 

[ah.b.normal]

How do I check if the relay is ok? The car ran great right before I strippped it apart. For what that’s worth.

Swap it with the horn or headlight relay if they are the same, cheap checker! As Ross mentioned, the gray wire is hot just as you turn the key on but I'd bet if it gets no signal from the fuel pressure circuit it shuts right off to prevent fire! I am speculating on this exact logic as I turn my ignition switch on, the brain(?) cycles the throttle butterfly and the fuel pump runs momentarily and stops due to a signal from somewhere? My bet is a fuel pressure sensor BUT I have never had reason to explore this specific system. (((((Maybe the fuel pump pressure switch is in the pump? No, it can't switch off at the gray wire if it is in the fuel pump. I am curious how it is deciding, wow! a new anomaly for me to explore.)))

 

[Leo Zugner]

So I did a quick check of feeling the relay when I turn the key and I don’t feel a “click”. I also get .4 volts on the grey wire. Obviously not 12 b but strange that there’s any at all? Also, can you all confirm the fuses and relays look like they are in the right spot? Don’t know why they wouldn’t be but just want to be sure. Also it looks like some relays are upside down based on the text on them. Should I go ahead and wire up the new pump incase it’s absence is the problem?

 

[ah.b.normal]

The 4 pole relays poles are on the diagonal axis so can only be installed correctly. even when the print is upside down. Pretty tricky eh?

 

[ah.b.normal]

Swap the relay with a working one. The AC relay or the Aftercooler pump relay.
Test #2: put your finger on the relay, can you feel it go click when the key it turned on?
It should throw the relay whether the fuel pump is hooked up or not.

Mad I can only up vote this post once! Brilliant!

 

[Ross]

The pins 85 and 86 on a relay are used to energize the coil, and make the relay click.
When the PCM wants fuel pressure, it uses this low amperage circuit to throw the switch.
This is not working on your goblin.

The pins 30 and 87 are part of the high amperage circuit that runs the fuel pump. So your grey wire having .4 volts is part of the fuel circuit after the relay/switch... which doesn't really matter if the relay/switch isn't working.

My 06 Cobalt seems to have a different fusebox than your 05. I highlighted the fuel pump fuse and relay with an orange square.

We need to figure out why the PCM isn't energizing the fuel pump relay...
What OBDii codes does your car have?

 

[Leo Zugner]

So you think that relay needs to be replaced?

 

[Ross]

Only if it is a defective relay. Have you swapped it, and tested if it does the same?
You can bench test the relay too. Just give it 12V and ground, and it should click.

 

[Gtstorey]

The relay can also be tested with a 9v battery

 

[ah.b.normal]

The relay can also be tested with a 9v battery

Cool Hack!!

 

[Leo Zugner]

Ok cool. I’ll try these.

 

[Leo Zugner]

Ok. Sort of a success. I put 12v to that relay like you showed in the pic and I felt a click. So we can at least cross that out? That must mean the fuse box isn’t getting 12v to that relay? I do get power to crank though. So it must just be to that particular area.

 

[Ross]

Okay, so the relay coil works. Good start.
We need to figure out why the PCM isn't energizing the fuel pump relay...
What OBDii codes does your car have?

 

[Leo Zugner]

I haven’t plugged that in yet but I’ll do that in a minute. Gonna have to put daughter to bed so might not have an answer till the morning. Thanks for your help!

 

[Leo Zugner]

Ok I couldn’t wait. Here are the codes I got:

P0223
0230
0449
0452
0463
1183
2138
0641
2228

 

[Gtstorey]

Ok I couldn’t wait. Here are the codes I got:

P0223
0230
0449
0452
0463
1183
2138
0641
2228

And do you want us to do the google search for what each code is? I doubt many of us have them memorized. I might do the search if it was only a couple but you should post the internet definition for them so we can pick out any important ones.