Help! Battery installed backwards!

[Petros]

Hi all,

New to this forum, but not new to fixing old cars. I am helping a young friend who has a 1974 912 with the EFI system. It has not been running for some 5 years except for the rare occasional start and short run.

Somehow the battery was installed backwards during one time when it was removed for recharging. I came over to help get the car started after it had not been running for about 8 months, the owner installed a new battery (swore he put in it in the same way it came out) and he was cranking and cranking it when I arrived. I found no spark and no fuel, and noticed the dash lights did not come on with the key in the "run" position. I inspected the battery and discovered the leads were connected to the wrong terminals. We corrected that and now the dash lights came on, but of course the car still would not start. Appears to have no spark since it would not even sputter when I sprayed starter fluid into the air cleaner (as a test).

So my question is, what most likely has to be replaced? I was surprised to find that this model still had the points and condenser distributor (rather than electronic ignition) even though it has the bosh electronic fuel injections system. It seems the ignition system should have not been harmed but it appears I am getting no spark. Also, how much damage would have been done to the fuel injection system? Anything else we should check or be concerned with?

Thanks

[Jim Chambers]

I am guessing that the ECU (electronic control unit, aka the "computer") would be damaged by wrong polarity. I have worked on many 914's but have very limited knowledge of electronics.
I suggest you post your question here. This group will have answers.
914World.com - A Porsche 914 Community / Forum / Club

[WRGREENER]

been there.... did this on my 72 (the new bat. had terminal positions reversed). i ended up having my ECU rebuilt (company out of Florida--core+300--great job). i burned up the diodes in the generator (replace whole thing). the one other area that was effected was the wiring harness that runs from the control panel to the gen/distributor. here is the tricky part. the ground wire in the wiring harness burned out. i saw the smoke while turning over the engine but could not see the damage because of the black harness wrap (well it burned thru in one small place) you will need to split open the harness and inspect for the burnt ground wire (green). since it did not burned any of the other wires i replaced the ground and re-wrapped. i can not speak about the EFI system....but i would open any wiring harness that you can get to for ground burn-out. i was lucky only that one area was effected on my car (that i could find). hope this helps

[Petros]

thanks for the advice. I have somethings to check out. I found a 912E fuel injection manual on-line, and will be working my way through that with these issues in mind.

Was the outfit in Florida called "Specialized ECU repair"? I found them on-line, replacement ecu is $275 with a 5-year warranty. Not bad at all.

[WRGREENER]

"specialized ECU repair" that is the place it.... came back like new.