New member! Car wont start!

[Porsche Noob]

Hey there, my name is Roman and I just recently purchased my 83 928s. The car has been running perfectly fine since I got it but today it decided to start acting up on me. The car started fine this morning and I drove it about 5-10 mins to the auto parts store. After I left the store the car would not start. I tried starting about 15 times letting it sit about 5 mins in between. I bought some starting fluid and sprayed it down the TB and the car sputtered to life then died a few seconds later. I can hear the fuel pump priming so I don't think that is the problem... I believe the fuel injectors are not pulsing for some reason. Does anyone have any advice for me?

[Maleficio]

I have some advice.

Your computer's MAIN ground is hidden underneath the supplemental air valve on the passenger side valve cover.

If that ground is loose, your car will not run. You can grab the valve and feel if it's not mounted tightly.

If you find that your computer ground is loose, you may have difficulty tightening it because of how it's mounted.

Do like I did and relocate the ground to the vacant screw hole on the opposite side of the valve cover, forward. You can then be sure it's mounted tightly, and you actually see it to make sure it's good in the future. Just splice in some new wiring to fit.

But essentially I'm saying to verify your grounds throughout the car, and this ground is the most important one, save for the battery ground.

Good luck, and report back.

[Porsche Noob]

I will check the ground when I go try again in a few hours. Thank you!

[Maleficio]

Originally Posted by Porsche Noob

I will check the ground when I go try again in a few hours. Thank you!

It's on the aft end of the cover. The valve has a large black rubber hose attached to it. The ground is hidden underneath it.

Start the car with starting fluid, loads of fluid to give you time, while it's idling, grab the valve and twist it, see what happens.

[Danglerb]

Green wire from dist to ign box does what yours is doing.

[Porsche Noob]

Ok so I tried wiggling the ground on the valvecover and the green wire to no avail. Looks like I need to get the car towed because it is getting too dark. I am picking up a noids light tomorrow to confirm pulse to the injectors. Thanks for the help so far.

[kelanel]

i know this sounds semi silly, but ive had similar issues to my o2 sensor being wirefaulted (thanks to some not so clever splicing to extend wires with headers that pushed things back), cold starts fine, then randomly if i let it sit for 10-15 mins then start again, it would not start for another 45 mins until it was cooled down. likely not the cause in this case, something to look at then laugh at me later (i sure did laugh when i found it)

[kelanel]

and welcome!

[924CarreraGTP]

So nobody thought that it might be a good idea to check the fuel injection relay in the passenger's side footwell? It's a good place to start. Jump the relay on the appropriate pins and see if it starts. I think there's a link on how to do this on 928INTL.com

[Porsche Noob]

Originally Posted by 924CarreraGTP

So nobody thought that it might be a good idea to check the fuel injection relay in the passenger's side footwell? It's a good place to start. Jump the relay on the appropriate pins and see if it starts. I think there's a link on how to do this on 928INTL.com

I would like to try this! I couldn't find the link on the how-to though.

[924CarreraGTP]

Not sure. You might search this forum for it. I think the fuel injection relay is the same as a couple of other relays in the car. Find an unimportant system and switch it out with a different relay. If you have the owners manual, read the relay list and look for simular relays on systems that don't matter. Some of them have the same numbers on the relays themselves like 53, and 24, but I don't remember which ones are which. I would have to look at a 928 relay panel. I would try that though, and make sure your fuel pump relay is working. Check viable fuses to these systems.
Other than that these guys have some good advice. The green wire is troublesome. I believe the speed reference sensor can cause problems like this too. I've been trying to help a local troubleshoot his 1980 928 and it sounds simular to what you are saying.
Check all connections to the fuel injection any time this kinda thing happens. Chances are it's relays rather than wiring issues unless some wiring genius PO has a bunch of stuff jerry rigged. That happens too. Don't rule out the Jetronic brain if you don't figure it out with these ideas.

[stepson]

Fuel injection relay is specific to this function. There is no substitute for it already in your central fuse panel. Here is the 928gt.com link to the relays and fuses:928 SPECIALISTS... dedicated to the restoration preservation and enhancement of your 928 Go the tips/links fuses and relays for your model year on the left side of the page.

You can remove the relay (XVI; 4th relay from the top right) and use a 3 prong jumper wire in its place to remove or confirm the fuel injection relay as the possible cause of your issues. Terminal 30 should be connected to both terminal 87's. The terminal numbers are marked on the spade end of the relay. Match up those terminal numbers with the corresponding slots on the relay panel and you should be good to test.

[Porsche Noob]

It started.... Looks like I need a new relay

[Danglerb]

Quoting Jim Bailey, relay, relay, relay.

[stepson]

Originally Posted by Danglerb

Quoting Jim Bailey, relay, relay, relay.

I was gonna quote Jim earlier, but I was afraid the irony might be wasted on a noobie, so I just thought I would just give instructions instead.

I guess the OP is saying it started with the jumper. Glad to hear it!

[924CarreraGTP]

Always suspect your relays first! When that fails, check fuses, when that fails check wiring, then the Jetronic, clogged fuel injectors, green wire, spark, etc.
Any engine runs with fuel, air, spark, and compression. The 928 needs the injection to function, and fuel to even have a chance of running badly. If it gets fire, you're half way there. If not, start trying to find out why.
It's good that you got it started, and that you reported back what you found. That's what this forum is for. If it's used correctly, we can all benefit from it.

[Porsche Noob]

I really appreciate you guys helping me out. I probably would have been troubleshooting for a loooong time. I look forward to learning more from you guys!

[bfieb123]

Originally Posted by Porsche Noob

Hey there, my name is Roman and I just recently purchased my 83 928s. The car has been running perfectly fine since I got it but today it decided to start acting up on me. The car started fine this morning and I drove it about 5-10 mins to the auto parts store. After I left the store the car would not start. I tried starting about 15 times letting it sit about 5 mins in between. I bought some starting fluid and sprayed it down the TB and the car sputtered to life then died a few seconds later. I can hear the fuel pump priming so I don't think that is the problem... I believe the fuel injectors are not pulsing for some reason. Does anyone have any advice for me?

Squirt starter fluid in the intake.If it fires for a short burst you may have a plugged fuel filter, bad fuel pump,no vacuum to the fuel pressure regulator,ignition module failure

[gjmascoli]

um, he got it started.

[MPDano]

Originally Posted by 924CarreraGTP

So nobody thought that it might be a good idea to check the fuel injection relay in the passenger's side footwell? It's a good place to start. Jump the relay on the appropriate pins and see if it starts. I think there's a link on how to do this on 928INTL.com

Ding Ding Ding, the Winnah!!