Electrical How To Proceed

[Matthias]

my horse is giving me trouble. I think it might be connected to a lot of rain we had in LA over the last weeks.

I was driving just a few days ago, no problems... then just two days later I start up the car and it dies immediately. I could keep it running by going into neutral and giving gas, but it dies immediately when idling. I also noticed the following:

- I can't pull the codes, my reader just starts beeping constantly, even with key off.
- when I turn the key in ON position (engine off) the fan kicks in. this is odd, it usually never does that.
- instead I usually hear the fuel pump for two seconds or so, but now it does not respond, instead, the fan comes on
- I tried it this morning again and at first I was happy, no fan, fuel pump came on and car idling smoothly. but after 15sec, dead. fan comes on, no chance to keep it running without kicking the gas.

I checked the fuses, all good. tank is half full.

So what could it be? fuel pump gone bad? but why the problems reading the codes? I suspect a short somewhere due to some accumulated water, but any of you guys having a suggestion where to start looking? I checked the engine compartment and it seems dry. maybe somewhere in the back where the fuel pump is located?

Your help is very much appreciated!


95 Mustang GT, 5.0, convertible, stock

 

[jozsefsz]

Do you happen to have a chip installed? (Like SCT or Moates?) Your computer is acting like mine when it lost its tune after the battery went dead. Check by the computer - behind the passenger kick-panel to see if it's gotten wet. A bad fuel pump wouldn't cause the fan to come on. You could possibly also have some water having fouled up the CCRM (relay module by the radiator overflow). That sends power to the computer and the fans. Good luck!

 

[Matthias]

Thanks for your help!
no chip installed yet, thought about doing it soon, but that's a different topic.
No rain for a few days now and it is getting better: yesterday morning I could fire it up but it again died after 15s. Today already two out of four successful. Kinda strange...
After three days of sun I have been still noticing a little puddle in front of the right rear wheel. it's water for sure. isn't that where the fuel pump sits? maybe it shortens the pump and this messes with the computer?

 

[jozsefsz]

The fuel pump is in the tank on our cars. There is a fuel pump inertia switch in the trunk but I'd be surprised if that got wet (it's pretty high up). Even if the fuel pump were shorted, it would likely blow the fuse for the pump itself. It's the fan turning on that concerns me more than the car dying -- there are a lot of possible explanations for that -- since that's a sign of distress in the computer.

 

[Dan_Soprano]

Sounds like the CCRM to me. I'd also pull the passanger side kick panel and see if the ECU got wet.

 

[Matthias]

Checked both, CCRM on the fan and the ECU, both seem dry to me.

Another thing I want to mention. I noticed that when the fan comes on (koeo) and I jiggle the key a bit I might get lucky and the fan goes off again, then the fuel pump comes on and I can start the car. either fan or fuel pump. maybe the ignition switch? just tapping in the dark...

the problem doesn't appear anymore right now but there is a lot of rain coming tomorrow. will get a cover...