billstevensvb

My 1991 GT is my fourth 928 and a well-maintained 80,000 mile vehicle in outstanding condition - except:
It has started...stopping. At speed, in gear, and otherwise running perfectly - all the dashboard icons will suddenly illuminate, the engine will simultaneously instantly, simply stop running and I will lose power steering and braking will also get heavy and less responsive. The internal electronics such as stereo, fans, etc continue to work but the engine is no longer running.
I turn off all internal power demands such as stereo, etc and re-turn the key - the car restarts like a normal start-up and resumes running normally.
This happened 2 or 3 three times over 6 months so I just stayed conscious of how frequently it occurred. Then it happened 5 times yesterday.
I was able to re-start and get home. I have an appointment to take the car to Hendrick Porsche here in Charlotte and it will be seen by Jim Burton - who is very knowledgeable about the 928.
I thought about fuel lines, fuel pump or fuel starvation, electronic/battery or alternator problems and was also told to check the crank sensor.
Has anyone seen anything similar or have any ideas where I might point Hendrick to give them a head start on a solution please?

Mrmerlin

spray the front and back of the CE panel with deoxit after you have removed the fuses and relays.

Spray the 14 pin connector under the hood and clean the battery connections and ground strap,
and the ground under the rear quarter liner, and the grounds in the spare tire well.

You should also replace one at a time the 4 running relays, ignition, fuel pump, LH and EZK relays,
and swap in a new fuel pump fuse after doing the deoxit spray.

I think you have a corrosion issue here for the no run, so do the simple things first
__________________

dr bob

[ I was typing then got called for dinner in the middle of the message, so there's a lot of overlap with Stan's recommendations]


Before you go spending big on dealer techs who will likely be seeing their first 928 in the flesh, invest a little time and a few dollars in some basic stuff that may easily solve the problem. Even if it doesn't, it's preventive maintenance to avoid your current symptoms.

1) "Relay-Relay-Relay" is the mantra of very knowledgeable 928 Guru Jim Bailey, and the followers have learned that this is a great place to start. Three critical relays are needed for the car to run. These are the EZK relay fro ignition, the LH relay for the fuel injection, and the fuel pump relay. (reaches for the workshop manuals, thumbs to 1991 and the electricals... flip-flip-flip and unfold the pages) The EZK relay is in position XXII, LH-Jetronic relay is in position XXV, and the fuel pump relay is in position XXVI, all in the central electrics panel. bottom of the passenger's footwell against the firewall. Lift the carpet out, and it's forward of the wood (!!) footboard. That board is hinged so it swings up.

2) Before you get into the relays, disconnect the battery ground strap at the rear of the car. The tool cover comes off, and the strap is bolted to the frame rail about the middle of the car. Remove the bolt, lift the strap crefully, and put something under the end to keep it from contacting any metals parts while you work.

There is a diagram of relay locations in a plastic retainer on the board the covers the CE panel. Else, the relay numbers are on the plastic panel itself next to each of the relays.

The relays come out using a couple paint-can openers, the ones with the bent ends. Get those ends under opposite sides of the target relay, and roll the opener to pry the relay loose from the bottom. They are stick in there pretty well!

The relays are commonly called "53B" relays due to their original Bosch part number. A call to one of our 928 parts vendors will get some on the way to you. Not expensive at all in the giant scheme of Porsche parts costs.


After that's done, you'll want to clean and inspect the connections on the positive battery terminal, the little ones that are bolted to that little plate fitting. Those operate the fans, fuel pump, and the injection. So any loose connections on the FI or fuel pump wires will stop the car, yet leave the dash lights and indicators working.

Randy V

DeOxit is not the panacea that Stan evangelizes about.

Seems every post from him includes hosing down the car with DeOxit.

Come on dude.

The Forgotten On

Deoxit is a great contact cleaner, but that is it as that is what it is designed for. Your issue is much more severe than anything deoxit can fix.

I recommend looking over all of your connections in your engine bay as the 3 pin connections for knock sensors and the hall sensor are commonly broken or cracked which can cause severe corrosion.

Another thing that can cause all of your lights to illuminate, from what I have heard, is a bad alternator. Which can wreak all sorts of havoc.

A faulty ignition switch could also cause those sorts of issues because the electronic part on the back could be worn and slowly move out of position 2, where the engine is running,
into position 1 where just the accessories are running. It's another thing to check if it is original.

M. Requin

You heard right. I just had my alternator fail (on a long trip, unfortunately - I'll post a write-up shortly), and that is exactly what happened- all the dash lights came on instantly. Fortunately I could restart the car and limp to a place to park it.

siscogts

at the moment i suggest checking alternator and also bad contactsto the ignition switch....

Francesco

dr bob

Relay-Relay-Relay. Repeat as needed.

The 'starts fine but then just dies', coupled with the 'been happening for the past six months but just now getting worse' do not point to the alternator. It points to the fuel pump relay, and the power supply to it. The pump itself doesn't give these symptoms, usually just one or two weak episodes then total failure. So I'm offering odds for relay and power connection as the cause.

FiveElements

It could be as simple as poor connections with some of the fuses. I had similar issues, and after pulling the fuses and bending them slightly so the contacts were more angled to the fuse panel pluggs, the car stopped stalling.

Payload

What else is on your keychain? The weight may be rotating your ignition switch back into the acc position, which would explain why all the warning lights come on and everything else non-engine related keeps working.

WallyP

Adding to "all the above" - After you disconnect the ground strap, open the battery box and carefully clean all of the connectors, especially the smaller connectors on the positive terminal. Just because...