SHO engine cut out...Fuel pump codes

[Rockledge]

OK, here's the scoop.

I'm driving along and all of the sudden the SHO cuts out, seemingly at the same time that I went over a small bump. It almost seemed to me like it had popped out of gear, that's how quick it died. I was able to restart it and it ran fine for another mile or so, and then same thing. Now it won't start at all. Tried cranking it many times thinking it might have been related to a CMP sensor problem, but no start.

It was dark, but I was still able to pull codes codes, here's what I get:

543 - Fuel pump monitor circuit shows no power

524 - Problem in low speed fuel pump circuit

Of course I'm thinking bad relay and/or fuel pump now but I tried pushing in the fuel pressure relief valve and it seemed to be spraying out plenty of fuel, which would seem to indicate it's getting fuel, no? shrug

On a related note, I had gotten a 542 (Fuel pump open, bad ground or always on) code a few months ago but it went away when I replaced my 02 sensors. And yes the pump was noisy.

Thanks in advance for any feedback.

 

[revhardSHO]

It may be the fuel shut off. To reset this there is a switch in the trunk on the left had side, simply press down.

 

[SHO_Driver]

Check that pump is getting power, does it still prime with ignition on?

If the pump has power then you know the lack of pressure is from the pump.

 

[billyshoe]

I found the fuel pump experience to be caused buy a loose spade terminal on the fuel pump. this terminal (inside the tank) probably loosened because if hi resistance at the connection due to a overheated pump. I just replaceded the pump and no problems followed. If the pump fails you can maybe get it to work temporary if you rap the tank with a soft hammer. It might save you a tow.

<small>[ November 20, 2003, 01:59 PM: Message edited by: billyshoe ]</small>

 

[Rockledge]

Thanks for the replies.

Well, here's where I'm at:

Tried the intertia switch, but no go.

The fuel pump does not prime when the ignition is turned to the "key on" position.

I grounded the fuel pump test pin at the EEC-V connector and heard the click from the CCRM, but still no fuel pump operation.

But, when I disconnected the CCRM and jumped the #5 connector to 12V, I heard the fuel pump come on (like I said, it's noisy).

So you think it might be a bad CCRM?

 

[projectSHO89]

Sounds very possible.

This might help: Fuel pump troubleshooting

Steve

 

[sdpatt]

With a second person turning the ignition key turned to START, slap your hand on the CCRM and see if the relay spins the pump to start the engine. If so, the CCRM is faulty.

 

[Rockledge]

Thanks for the info. The hand slapping procedure will be the first thing I try when I get back at it tomorrow.

I also read through the link that Steve referenced and see a few things I can try since I do have a decent digital multi meter. However, so I don't end up accidently cooking my SHO's computer system, I'd like to be sure about my testing methods. Hoping you guys can help straighten me out, if necessary. Here's my questions:

(a) After I ground the fuel pump test pin on the EEC connector, if the pump does not run (and it hasn’t so far with me doing that, only a click from the CCRM), I should then check the voltage at Pin 5 of the CCRM?

(b) To measure Pin 5 (PINK/BLACK) voltage, I should connect one side of the multi meter to Pin 5 and the other side to what, ground?

(c) The Pin 5 test reading should be full battery voltage (~12v)?

(d) I should also be getting battery voltage from Pin 12 (YELLOW)?

(e) I'm measuring Pin 5 and Pin 12 for voltage while the harness is still plugged into the module, correct?

Sorry to sound like a meatball on the testing process but I want to make sure I do it right so I don’t go off on a wild goose chase or fry the computer.

Again, thanks a bunch everyone!

 

[projectSHO89]

(a) Yes. You are checking to see if the relay inside the CCRM is routing power to the wire that leads to the inertia switch and the pump.

(b) Yes. All measurements are always referenced to ground unless otherwise specified. This is standard in electronics troubleshooting.

(c) If the circuit has a single speed fuel pump circuit, then yes. if there is a low speed fuel pump drive, then it will be partial battery voltage. Service documentation I have consulted indicates that the 94 MTX is a single speed pump.

(d) Yes. This is the input supply that is switched by the FP relay and actually runs the pump. If it is missing, check the 50A PCM/FP relay in the engine compartment fuse box.

(e) Yes.

Steve

 

[Rockledge]

Great feedback Steve, thank you.

I checked the #5 Pin and get pretty much nothing (.024v). Not even close to the 12v that are supposed to be there.

Also, I jumped the #5 Pin again and tried starting the motor. Fired right up.

So at this point I'm pretty sure the problem lies within the CCRM. So that's what I'm looking for right now.

Anyone know where I can get one cheap? Tried a few boneyards already and no luck.

 

[Rockledge]

Well, I looked around for a CCRM today but no luck yet. So I decided to drop the fuel tank and change the noisy pump, which I did this afternoon, as better described here.