1982 928 Various Electrical Issues

[raybob95]

So the car we're talking about here is a North America 1982 Porsche 928 with the normal 230-hp 4.5L V8 and a 3-speed auto, with ~120,000 miles. It had some major work on everything but electrical about 12 years ago.

The car is mechanically sound, but is being plagued by a number of electrical issues. Most of want I want to know is if this is most likely due to just contact corrosion if actual parts or wires need to be replaced.

The various symptoms include an alternator that began as charging the battery on and off and then stopped working completely (haven't tested the alternator yet, it might be just that), brake lights that are stuck on as of today (it used to be that they were stuck on until the first time you pushed the pedal, then they would work correctly), a tachometer that reads half the correct RPM (full rev reads about 3.5k) and drops to zero with the headlights turned on, a horn that would honk with the wheel turned all the way over, interior lights that never turn off, and now a fuel pump that has been replaced several times but still has the same bad electrical connection where it will just randomly cut out while driving and then refuse to start for a random length of time afterwards.

The biggest problem right now stopping me from driving it is the fuel pump. I never know when it's gonna cut out so I can't confidently drive it for any distance. I know the fuel pump itself is good; something electrical somewhere is wrong.

Any help would be appreciated. Thanks!

[nuts4porsche]

you need to go through the whole cars elect. system and clean or replace bad wires-rusted through or corroded bad and connectors. all grounds and bad wires a must.check relays and fuses-all good luck alot of good help here!

[924CarreraGTP]

Relays and fuses are a good start for fuel problems no doubt about it. Relays can slowly fail and cause problems like this.

[curtisr]

Would this help?



It's $13 at 20 Amp Automotive Fuse Circuit Tester

[lfausty]

fuel filter/check valve gunked inop not sending enough fuel through?

[harborman]

Change out all the relays you can. Mine had these #53 which were pretty cheap. Pull every fuse and clean all contacts. Do all of the above as mentioned. Clean main battery connections and main ground. Clean main connector 14 pin up front on passenger fender. Clean main ground body to engine under the car. This will keep you busy for a day or so.

[raybob95]

Can you explain where the main 14 pin connector is? Is that the one that you have to take out the rear seat to clean?

Also if I were to take out the dash and try to fix some of the gauges, approximately how long would that take to accomplish?

Lastly are you all saying that there's probably just a few corroded wires or contacts? My worst fear was that I would have to replace a whole circuit board or something. What are the odds of that being the case?

[924CarreraGTP]

Circuitboards.... Slim to none. You must realize the 928 was a lunar shuttle for it's day. Most of the electronics in the 928 are rock solid. Yes there are niggling problems with connections due to a steel and aluminum automobile, but mostly it comes down to contacts, relays, fuses, and plugs and contacts in the instrument cluster, switches, and a host of other nickle and dime kinda stuff.
Many people get overwhelmed with these things without realizing that the 928 has a pretty basic yet large and cumbersome looking electrical system. However, what you have to concentrate on is what systems make the car run and that often comes down to a couple of relays, and fuses.
When a 928 dies for good and you can't troubleshoot it with relays, fuses, contacts, and sensors that's usually the Jetronic brain, or wiring. Then it get's expensive. Especially for an early Jetronic car. Although, for all the stories out there about bad Jetronics, I've only physically seen a couple of them that were destroyed, and both were water damaged. I assure you they are a very rugged system.

[dcrasta]

Originally Posted by raybob95

The biggest problem right now stopping me from driving it is the fuel pump.

Start by reading the Sticky
then I would register on 'the other forum' and read the 928 FAQ

You are going to need to service all of the ground points, the CE Panel (there are a bunch of grounds there also).
You will need to inspect/replace the main ground from the body to the battery.
You will need to inspect/clean the 14 pin connector located near the passenger fender up front [engine bay]
You will need to pull your relays and fuses and clean the contacts (a small dremel with the brass wheel is your friend).
you should replace all of the bulbs with the correctly rated bulbs (side marker, parking light, brake, backup, blinkers)

(considering everything on this short list is just time and effort (not a bunch of $$) just do it, dont look at stuff thinking -its ok-, just do it.)

There is a brake light switch on the brake pedal arm. Check that for corrosion or a short.

Do those task and come back with the results..

[raybob95]

OK guys thanks for the help, I'll try some of this stuff sometime soon and I'll let you all know how it went.