There Was Power. And then there wasn't...

[Michigan944]

Hey everyone!

Late last year my dad decided he wanted to join the cool kids club and buy a Porsche. I already had a 944, so naturally he wanted something different and with more power. In August we welcomed a 1985 928S Euro automatic into the family and it has been quite a different experience from working on my 944, so I need some help.

The PO's didn't do much to maintain the car, so we've been working through some struggles, mostly electrical. Today while I was out cleaning the inside of the car I went to move the seat back to reinstall the front carpets and the seat quit moving. I thought that maybe the motor gave out since the seat had always been kind of slow, but it tried the other seat and got the same thing. Then I tried the sunroof and I could hear the motor under load, but nothing happened. Same with both windows, I could hear them trying but nothing was happening. All of these things were functional last week and the car hasn't been driven since. I've also had the battery on the charger for an hour or so and still can't seem to get full power to anything electrical. I don't even get the annoying buzzer that comes on when you turn the ignition on.

Any ideas on what I can check or where to start to figure our what's going on?

Many thanks!

[Michigan944]

**Update

I went back out to the car after posting and to my surprise everything had power again, but then slowly died out to nothing. I went back to the battery and noticed that it sounded like it was boiling inside while it was on the charger... We will be charging the battery outside of the car now.

[honerboys]

does it start and run? - dead/bad battery?

[husker boxster]

Take the battery to a parts or battery store and have them check it. A smart man (JFP in PA) once told me to start simple when chasing electrical problems and expand out from there.

[harborman]

Check the braided ground strap on the negative post of the battery to frame. I found mine had corroded inside. It looked fine on the outside but had enough internal resistance the starter would barely crank over. Replaced it and all is fine now.

[Michigan944]

I've got a load tester and tested the battery the other day. It holds a charge and tests fine. It's most likely not that.

Thanks Harborman. I'll check that also. I'm starting to think there's a bad ground somewhere. I was finding corrosion all over on all sorts of wires in various parts of the car on Saturday. In addition to that, when we hooked the battery back up after having it pulled out of the car for a while, all the lights and the buzzer came on again like they were supposed to. Once we tried to start the car everything went dead. We could still hear the relays clicking, but the starter wouldn't turn over, the windows wouldn't go down, the sunroof didn't have enough power to move and the buzzer no longer came on.

[JK McDonald]

Hey Mich - It takes a lot of umph to spin these V8's over and because of where the battery is mounted, it's not uncommon for even a small amount of resistance to cause a 928 to experience electrical issues.

As other members have mentioned this sounds like a ground problem. Now that you've made sure that your battery is healthy, clean all ends of the battery cables, recheck the resistance of your main battery to ground "contact point" just under the tool panel at the rear hatch. Then if this main ground point is tight, remove and cleaned the short ground cable attached between the right side of the block to the frame -

Now add a second battery to the car..........Connect it using a good set of jumper cables to the "Positive Jumper Post" found on the inner front side of the passenger fender and the black cable solidly to the engine block. This should get your starter working and keep power to the basic key ON B+ circuitry.

Keep Us Posted - and Good Luck - Michael

[JK McDonald]

Hey Mich - All of us have had to sort through our wiring to some degree. This is especially true for a 928 that has been sitting for a while. The process is not overly difficult - just a bit time consuming.

Did re-verifying and cleaning all the main battery ground points help to resolve your loss of B+ power during start ? Adding in a second battery is an old trick to bypass most of the rear battery cabling as a trouble shooting step.

Once you've chased down the loss of B+ power when it's under load, next comes checking the fuse panel ground terminal lugs, fuses, relays, and all the electrical wiring plugs to get your fuel pump, ignition and fuel injection working. There are lots of experienced owners here who are glad to help you along as you go......

Michael

[harborman]

Also, clean main ground from block to frame under the car. Try jumping the battery Neg. ground to chassis with another cable.

[Michigan944]

Update:

I finally got around to tinkering with the 928 some more yesterday since finals are done for me now. I got the car jacked up and found out that one of the wires on the starter solenoid had wiggled loose. We had to jerry-rig it a while back because we found that the main power wire to the starter was corroded. We ran two wires through the firewall and attached them to a switch so we could start the car for the time being until we are able to remove the bad wire and replace it. One of those wires came loose and it wasn't getting a good enough connection. Crimped them back down and she fired up like a champ!

Thank you everyone for the help. It was much appreciated. I need to actually sit down and make a detailed list of everything that the car needs now so my dad knows where to start.

[JK McDonald]

Hey Michigan - Along with your list of things to repair, now is a good time to start your 928 maintenance log book. This will make it much easier to keep up with the date of a repair and help schedule routine tune-ups, oil/filter changes, track tire life, brake pads/fluid flush, radiator coolant age, etc.... I've filled several spiral notebooks on each of my cars over the years.

Dwayn's Garage - is an example of a list of areas typically needing attention on our 928's. It's an overview put together by one of several 928 gurus on the web......

One other tip - I'm not trying to spook you but as many owners will caution you - Don't put off replacing your high pressure fuel lines too long while trying to get your car back on the road.

Dwayne's Garage

Good Luck - Michael