dukenukemx

My uncle is giving me his Porsche 928 which has been sitting for a while. The car was abandoned because of electrical issues. So far I can have the engine running if I have someone spray the engine with starter fluid and I hold the ignition relay closed. Some reason the ignition relay and fuel pump relay don't engage, but I know I can make them work with a car battery. Both wires to the fuel pump go straight to ground, which I don't know why, but I ran wires from the battery to the pump and it does pump fuel, but the injectors don't seem to engage either.

He swears he ran when he last parked it 8 years ago. What will prevent the relays from getting power? Could it be a dirty ignition switch?

dukenukemx

Was doing a bit of research and I realize that the symptoms might be related to a faulty kick-down relay. BTW this car has an automatic. I'll need to get a photo of the fuse box to see if I can determine if that relay is installed and not the wrong one. Someone else did mess with this car before.

Mrmerlin

at this point best to clean the battery terminals and replace the 3 running relays ,
Fuel pump, EZF and LH IIRC they are all 53 relays

The Forgotten On

Start off with the obvious and replace the ignition switch. They can cause all kinds of weird issues with the gauges and all other systems in the car.

With how old our cars are it is very prudent to just do this to get it out of the way.

Also check the rear main ground to see if it is corroded. Again, when they go bad from battery vapors corroding them under their sheath they cause all kinds of weird issues.

Just to be extra safe, clean EVERY ground point in the car. Dirty grounds will cause most electrical issues.

As suggested above by Stan (one of the most knowledgeable people here), replace all standard 4 pin relays (known as 53 relays here). Make sure to get quality parts that are made in Germany for this one as the Chinese ones are iffy.

What most likely happened with your car (and most of ours) is the sealant around the recirc housing above the fuse panel failed and allowed water to drip onto the fuse panel among other things in the passenger's footwell.

You should go over this area and clean every connection along with spraying it with DeOxIt (your new best friend with these cars) to remove and prevent new corrosion from occurring.

BTW welcome to Rennlist, we're all a little crazy here when it comes to our cars

dukenukemx

First thing I did was clean the battery terminals, include the ground wire where it bolted to the car. The car didn't even crank until I replaced the starter relay with a nearby 53 relay. I'm gonna try to order 4 of those relays since I already found one faulty. Only place I can find them is Ebay, will these work?

https://www.ebay.com/itm/Porsche-Relay-928-multi-purpose-starter-horn-blower-defroster-power-window-new/361557316275?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

Thanks, I'll look for a replacement.
Already cleaned it and added another cable to make sure the ground is good.
Do you have a diagram which shows where those ground points are? This car sat outside for 8 years and is surrounded by grass, so find these grounds is gonna be painful.

Someone else replaced that panel, so that would explain it. Something I'll have to keep in mind once this car runs.

Thanks, I think I'll fit in.

SeanR

Wisconsin Joe

"Running when parked". Sure. They all were.

Have you read through the "New Visitor" sticky yet?

If not, you should.

One of the many things listed in it are several trusted and respected vendors. Known as the "Big 4".

You can get good relays from them, and it won't cost much more than the cheapest E-Bay seller. Certainly less than the Wherle listed in that ad. Bosch is suggested.
You can get an ignition switch that isn't a cheap Chinese one from them too.

Ground points are also listed there.

If your CE panel was replaced, make sure the replacement is from the same year. They may look the same, but there are a lot of differences.

And, as is a bit of a running gag around here:

THIS...

Landseer

Grounds of importance are just above CE panel, also at both sides of the very back of the block, at base of V, close to firewall --- which btw are the critical grounds for computer and engine control sensors and injectors via computer. You will need 10 mm socket on long 1/4 inch drive extn, plus a good magnet on a stick to navigate these. Be thinking about replacing fuel lines too before driving, talk to Roger about options.

There is a ground point for fuel pump and rear lighting beneath the rear corner of the interior quarter panel, passenger side. It might be possible to partially detach that panel and reach that ground without breaking the quarter panel. To remove panel and get better access requires removing rear seat cushion and back, a methodical process.

The battery ground plastic generally hides the corrosion deteriorization of the fine copper braid, so cleaning ends is often pointless, best to replace that one, talk to Roger. I realize you'e
Augmented it with a parallel ground, but know it's a real source for voltage drop during deep draw of starting and can limit the control voltage at the back of the relays. Especially through an imperfect ign switch. See how this stuff adds up?

Beneath car on passenger side you will see a braided cable linking engine to body, best to clean ends on that one.

These are the relevant ones. Ign switch replacement is also a good call.

87 30 can be jumpered on those relays to bypass them using a spade end on each end of a jumper wire instead of relay. Testing puposes.

...THREAD....

PorKen

Does the tach needle move while cranking? If not, the Crank Position Sensor or its plug are suspect.

The fuel pump relay will not close until there are RPMs detected.

The Forgotten On

IS.......

gomez123

I think but not sure
USELESS

Landseer

...WITHOUT...

dukenukemx

Thanks, this is exactly what I needed to know. The 928 is a good 2 1/2 hour drive from where I live so I need to load up on what I can to try and get it running. I ordered relays, gonna bring a multimeter, and now I'll bring a 10mm socket and extension as well. My uncle has tools but I'd rather come prepared. BTW is this what the engine ground looks like?


I took both wires off the fuel pump and both wires go to ground. Not sure why that is? Also I ran wires from the battery to the pump and got it running, so I know the pump is good. I tried running the pump while cranking the engine and no good. I'm guessing the fuel injectors aren't working.

What I did was a temporary solution. Once I can start the car I'll get a nice new ground cable. I noticed when I was hooking the battery that under the plastic protection that there was corrosion.
So this engine has three grounds?

Oh god, this has a crank position sensor? That's pretty advanced for 1985. I didn't pay attention to the tach, but next I will. Are there 2 crank position sensors? Also, are they hard to get to?

bureau13

PICS!

Well, you did post one, but we always want more pics.

Only one CPS that I know of, my previous owner replaced the sensor and connector before selling it to me, so I haven't messed with it yet...

Wisconsin Joe

Keep in mind that this was one of the most advanced cars for it's time. Not so much for today, but it was well ahead of most of the rest of the cars on the road back then.

CPS, Temp2, MAF, all that stuff wasn't common for a number of years.

Only one sensor, AFAIK Mr Merlin corrected me and said that there are two. Trust him over me. Every time. Not terribly hard to access, but it may be somewhat difficult to remove. Plenty of threads on the trials & tribulations of that particular task.

Roger at 928s R Us carries the sensor. He has a Bosch equivalent that is far, far cheaper than the one in the Porsche box.