User 41221

The car in question is a '84 944, that *was* running perfectly... My 2008 Chevy Colorado went dead after sitting too long, so I figured I would jump it with my 944 since it was the car I had driven to work when I discovered the truck wouldn't start. I hooked up the jumper cables to the battery in the 944, and figured that I didn't need to start the 944 during the process. The truck started right up, and I decided to drive the truck around to charge the battery back up, so I left the 944 where it was and just closed it up. When I came back the next day, the 944 wouldn't start, and had no tach bounce. *sigh*

I had to go on a business trip the next day, and was gone for two weeks. I checked the fuel pump fuse (loc 2 on the aux panel) and popped in a spare DME that I have, and got no change.

Questions... aside from checking the fuel pump relay (which I didn't have a spare on hand at the office where my car currently sits), anyone have any other suggestions? I am having a hard time believing that the three seconds the jumper cables were on the battery with the ignition off was enough to disable the car.

Regards,

knfeparty

I would put a battery charger on there before I did anything. That starter for your 2008 Chevy probably puts out more horsepower than the engine on your 944 does. I'll bet it sapped the battery down to low enough voltage that the current (already high because you're cranking) skyrocketed and blew a fuse/burned up a wire.

Jfrahm

How do you blow a fuse with voltage?

I'd try charging/jumping the 944 and failing that try the usual no-start stuff.

http://www.clarks-garage.com/shop-manual/fuel-05.htm

User 41221

The car is cranking over fine, the battery has plenty of juice at the moment. Looks like I need to grab my spare fuel pump relay or failing that, break out the volt-ohm meter and start checking...

Thanks! Keep the ideas coming.

Regards,

harrisonrick

dme relay, fuel pump relay...?

V2Rocket

i think this is the reason you start the "donor" car lol

User 41221

The early cars use a "fuel pump relay", which is the same thing as the "DME relay". Unfortunately, its tucked up in a relatively tough locations to access (its easiest to drop the aux fuse panel so that you can get to it). Since its a mechanical switch and I didn't have the key in the ignition, I assumed that it should have been safe. Its the next thing on my list to swap out, just need to get the time to do it, when its not raining...

Thanks again!

Regards,

knfeparty

You don't; love voltage causes high current, which blows fuses. This is why if a car sits for awhile sometimes you'll try to crank with a low battery and the fuse will blow.

User 41221

Just to wrap this up... it was the wire that runs from the battery to the starter. How it was that jumping another vehicle caused it to fail is beyond me, as it has no obvious burn marks, but its the only wire I couldn't get voltage on (and trust me, this was a LOT of fun in a rain soaked parking lot at work), but the wire is replaced now and the car is running again.

Old wiring sucks...

Regards,