Noth

Hi All,
Sorry to make my first post a question but I'm a little stumped.

I recently purchased a 1980 non US model 928, the motor starts when I turn the key first time but it will only run for around 30 seconds. Doing this a couple more times will result in the car idling normally. Personally I think this isn't too shabby for a 30 year old car that hasn't been run for the last 6 months. I also get a warning indicator light on the dash (exclamation point on the console) I can press the button on the centre console and that light will go away but I'm thinking that's a bad thing.

I've noticed that you can get digital testers to diagnose errors in the later models, is there a tester for the 1980 model?

I have the workshop manual and would prefer to fix the issue myself if its possible, I don't mind spending money on parts to get it perfect but I'd prefer to save money by not replacing parts which aren't broken. At the moment I have purchased vacuum lines from 928 Motorsports and am in the process of replacing vacuum lines as I was told by the previous owner who took the car to a Porsche mechanic that the issue related to old vacuum lines, I am having a bit of a problem finding all these lines since there isn't really a section in the manual which relates to replacing all vacuum lines, just single lines, if anyone has any resources even if its only a few helpful page numbers from the manual on replacing vacuum lines I'd really appreciate it.

My issue is that the car isn't registered and I'd have to tow it a couple of hours to get to a Porsche mechanic who would have any idea what a 928 is. In my part of the world (Sunshine Coast in Australia) these cars are very rare.

Cheers,
Noth

dogleg

hi i have the same spec car and maybe the same fault.when the car eventually idles from cold does it run badly making in difficult to drive un'till its fully warmed up them its almost running right?light on the dash i think is seatbelt warning light i'll check mine again could you post a pic of the warning light.

Dennis Wilson

1. Since the car hasn't been run in a while, cleaning of the fuse. relay and grounds contacts are in order and may fix a potential heating problem with the auxillary air valve.

2. The auxillary air valve could be sticking open and that coupled with any vacuum leaks could cause your problems.

3. A dirty air sensor plate or gummed piston in the fuel distributor could also be the cause.

Guess what I am saying is that any CIS injected vehicle that has sat too long needs a complete going over and tune. Replacing the vacuum lines is a good start.

Dennis

Noth

Thanks for the responses. Does anyone know a good guide for vacuum line replacement or a diagram of where all the lines are. I think (not 100% certain) that the original vacuum lines have been replaced with lines marked fuel line in the past but I don't want to replace the wrong hose and cause an issue.

I will post up a pic of the warning light tonight.

Noth

OK here is a picture of the warning light.

And there is a light on the centre dash, this light is a button and if you press the button both the light on the dash and centre dash go out.

Here is a video of two attempts at starting the car.

sndrunr1

There is a mesh filter in fuel inlet line at CIS, which got stopped up on my '80 Euro, and did about the same thing. As far as the vacuum lines, I put (yellow) silicone vacuum lines on mine, only because no one would probably use that color. Pic of my motor on EBAY on sellers ad for Porsche 928 silicone vacuum lines.

Noth

Thanks, really useful responses I will check out the auxillary air valve, fuel distributor (at the same time taking a look at the inlet line) and finish of the vacuum line replacement and see if I can sort it out. This information really did save me a great deal of guesswork and looking through the manuals at those areas what you're suggesting does make a lot of sense.

Dogleg: yep same issue but mine does run OK once its all warmed up. Have tried starting it with seatbelt in and that didn't affect the dashboard light, doesn't mean the seatbelt sensor doesn't have an electrical issue though so I'll check that out just in case.

Dave928S

Noth ... The light in the centre is the central warning light which is alerting you to a malfunction of some sort, and the button with the exclamation mark is for cancelling the central warning light. If you have a fault it will come on, but can be cancelled if its not an engine breaking condition. It will come on every time you turn the ignition on as long as the fault still exists (like a nagging wife).

When the car is running you can tell what the fault is by looking for what individual warning light stays on in the instrument area ... and then you can troubleshoot from there to sort that individual problem out.

Sometimes it's as simple as a fuse gone or incorrect or mismatching bulbs, but in your case it looks like it might be an alternator issue. Notice when the car runs the voltmeter is at the bottom of the scale ... and you see warning lights .... that's the fault and the warning system is alerting you to that.

As it seems you have one electrical fault, it's a possibility that the engine dying might be electrical too. Fuel pressure/pump issue also seems possible. Get the electrical fault sorted first and clean all the important grounds .. and then go from there.

9two8

For what it,s worth I had very similar issues with my 1980 928 S Euro, about two years ago, start the car, and within a few seconds it would stall, just like your vid picture. The fuel filter on mine had partially collapsed, and the fuel line was crudded up, had the lines flushed through and new filter and that solved it.

Ken
80 928 S
5 Speed

UK

SMTCapeCod

IIRC, if you have the parking brake set, the red light stays on after you release the p-brake, until you step on the bake pedal-- or you tap the button. Here's hopin'.

rotaryboots

924's do this too. Same scenario though. It honestly sounds like its dying out from fuel starvation. Like the other poster said, if a CIS has sat for any period of time, things start going wrong. The fact that it does run normally after a few tries tells me that it finally builds up enough fuel pressure to run. How does it run after the idle? Does it rev and drive? First things first, if it has old gas get rid of it, change the fuel filter(s) including the one inside the fuel distributor (be carefull though, there's little pieces in the distributor that are very hard to replace if lost). The inlet line will be a direct feed to the block and shouldn't have anything T-ing off it except maybe one line that goes to the cold start injector. The return line is the one you need to be careful with because it has a ball, spacers, a spring, and a plunger inside it. Like I said, hard to replace, and they tend to wanna pop out when you undo that hose. (heads-up). Don't crack open the distributor unless you're certain you want to go down that road of trial and error for getting it to run right again after rebuilding it ...I for one hate rebuilding fuel distributors...

If it was my car. I'd remove the entire fuel distributor carefully, unscrew the nut holding or lightly bend the little tab that keep the slider from falling out slide the slider out, do a quick cleaning with some spray into the slider's opening, the slide definitely needs to move in-and-out of the hole smoothly......then set that aside. If it doesn't want to pop out, the top of the distributor has an inlet right in the middle. That goes directly to the top of the plunger hole...give it a little blow, and the slider will pop right out. (should) I'd disconnect all the injectors and clean the lines out. Disconnect the feed and return lines completely, then clear them out. Replace all the vacuum lines while you're under there, then hook it all back up with new/clean filters. Then I'd know everything was clear. And for safe measure, put some fuel injection system cleaner in with the new fuel.
Oh yeah, clean the fuel relay contacts and fuses like the other post said. As time goes by the contacts get arc-ed and bad leading to unreliable contacts. Actually, try that first since its one of the things 928's need attention in every few years anyways and could save you a lot of time if a relay ends up being the real problem. I haven't seen this typed anywhere on the forum yet while searching, but those relays can be opened up and the contacts can be cleaned with emery paper instead of replacing the entire relay. You could also try jumping the fuel pump relay, turning the key to on, let the fuel pump run for a few seconds, then try starting the engine and seeing what happens. This is actually how I kinda have my fuel pump set up in my old 931. Pretty sure this will be mentioned in the shop manual in the fuel section.
I noticed there something wrong with your gauges in the video. The oil psi is pegged, and the other gauges don't move. Sounds like more electrical fun on the to do list.


Nice, my first post here was CIS related, the years of 931, 911, and 924 CIS troubleshooting paid off.

Noth

Just an update on this in case anyone else comes across this same issue, turns out the previous owner took this car to an auto mechanic who either had no clue or had a clue and wanted to rip him off; the fuel pump relay was not installed. Purchased a new one and it now starts.... kind of... OK I have to cheat in order to get it to start but at least it starts every time. Everyone was 100% correct, the issue was fuel supply related.

Another issue has now come up, this one raised by my workaround to get it to start, someone in another thread (which I now cannot find) suggested taking off the air filter and putting a vacuum cleaner hose down there, new fuel relay installed and still having issues starting it I was desperate enough to give it a go, I was just a little surprised to find out this worked.

I can now start my car every time as long as I have my driver door open and stick a screwdriver down into a hole which seems specially built for this purpose in the air filter cover.



This seems to open the gate which allows initial airflow through then once it has built up a flow of air the engine will run smoothly. I am trying to figure out if this air intake might be the only issue remaining so that I don't have to take apart the fuel distributor (which from the post above sounds like something I should try and avoid) before attempting to tackle the obvious electrical gremlins which are causing my dials to not read correctly.

So far since last post I've put in a new distributor cap, spark plugs, replaced remaining vacuum lines (someone had them switched around, new ones in now installed as per the diagram), new intake manifold rubber connectors, fuel pump relay and I'll be putting in a new fuel filter and draining out the fuel this weekend.

Probably my biggest issue is parts take around a month to be delivered, I'd honestly prefer to buy too many new parts and stand a better chance of having this fixed in one go than keep ordering in small quantities to try and diagnose exactly what is going wrong. Once running the car does drive, not very nicely (auto transmission servicing kit is on my next shopping list, along with power steering fluid and a MityVac which I am thinking may come in handy) and once running it keeps running and will start again once I turn it off unless I leave it overnight. All of this leads me to believe it's not electrical and more likely a vacuum issue as once pressure is built up it seems to work fine. Any advice on what to look at or a best solution for what to purchase next would be greatly appreciated.

ROG100

Shipping parts to Australia should take 6 to 10 business days using USPS Priority Mail. Quicker if you use DHL/FedEx.
There were a few slow deliveries in Sept/Oct but the majority made it on time.

Dennis Wilson

Pushing down on the A/F adjuster causes the air sensor plate to raise the piston and richens the mixture. On cold starts this is normally accomplished by the cold start valve. Have you checked the CSV to make sure it is getting 12 volts during cranking? If not, check the connection at the starter and ground.

Dennis

Mike LaBranche

As Dennis points out, the circled area in your picture is the Air/Fuel adjustment screw/spring, adjusts idle mixture, you set it and forget it. It's interesting that you have what appears to be a pressure gauge next to the warm up regulator (wur). What values are you seeing there?

Chances are your problems are crud/gunk in the system. A good dose of Berryman's or some other fuel detergent run through the system will work wonders. You can jumper the fuel pump relay after adding to the tank and circulate without starting, let it run that way for 10-15 minutes. Best thing is to drive it, fresh fuel, drive it, etc.