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TOPIC: New to the Houston 928 community - Car stopped running

New to the Houston 928 community - Car stopped running 03 Jul 2017 19:21 #19853


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Hello! I’m new to the 928 community here in Houston. I have a 1981 928 – it is in great shape and a blast to drive. It has a basic engine, no charger or turbo and it has been running great for the past year. The other day while driving it just cut-out and the engine stopped. There was nothing wrong with the starter, battery, engine would “crank” fine, but I got no smell of gas, as if nothing was getting to the engine. I had a new fuel filter and fuel pump in my spare bag, so I changed them out one at a time.
After changing the filter didn’t help, I changed the fuel pump, the engine started on the first try. I thought my problem was solved. After about 2 hours though, it stopped again and would not start.
Now I am looking for either new ideas, or a great, inexpensive place to take it and trouble shoot.
Anybody know of a good place in the Houston area? Or any troubleshooting steps that could help me narrow down what could be wrong?
I would appreciate any help you’all can provide.

P928.jpg
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New to the Houston 928 community - Car stopped running 05 Jul 2017 11:14 #19855


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Hello Dennis,

You have a very nice looking Porsche 928. I suggest the following:
a) Clean the positive and negative connections at the battery. Check the multiple connections that bolt to the positive cable. Inspect the negative cable, sometimes there is corrosion that has damaged the copper under the plastic covered section. Replace if necessary.

b) If you have never changed out the relays or cleaned out the fuses in your Porsche 928, I suggest.

Look to your owners manual for the position of these items in your fuse panel (aka Central Electric)

1. Fuel pump fuse #22 (25 Amp): clean the fuse ends and retainers (good idea to do this for all fuses, do ONE AT A TIME).

2. Replace these relays

Relay # XVI : Fuel Injection Part Number 928.615.119.00
Relay # XVII: Fuel Pump Part Number 928.615.113.01 (note, this is a special relay that has an RPM sensing circuit inside)

If the problem goes away, you're good to go. If not, you need to go into full diagnosis mode and determine if there is spark when the engine will not start. If no spark, that has to be fixed because the spark system triggers the fuel injection.

If you'd like to contact me for more suggestions, drop a note to info at electronikrepair.com
Rich
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1993 928 GTS Cover Girl
1987 928 S4
1979 928 5-speed rescue
1979 928 5-liter track beast
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New to the Houston 928 community - Car stopped running 09 Jul 2017 18:22 #19870


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Thank you~! and thanks for the information. i will let you know how it works.
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New to the Houston 928 community - Car stopped running 05 Oct 2017 15:28 #20007


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Thanks for the diagnosis. I now have the two relays and am ready to replace them, but I would really love to know what the issue is and if these fix it.
I’ve been starting the car and running it for about an hour ever two to three days. It runs great, I’ve even taken it out around the block a few times. But, never for too long,

I’m afraid of breaking down again, and my towing option doesn’t pay 100%.

From what I see I have 2 options:
1) Drive it until it “fails” again, change out the relays and see of it starts.
2) Change out the relays and send them “someplace” to be tested and evaluated. Drive the car and hope this fixed the problem.

Anyone see another option? Or know where I could send the relays to be tested?

Also, thanks to all the 928 members that reached out to me during and after the hurricane to ask how my car (and me) were doing (ha-ha) and came through the storm undamaged. We are the lucky ones. A lot of folks in my area were hit hard.[/b]
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New to the Houston 928 community - Car stopped running 06 Oct 2017 09:25 #20011


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US-spec or Euro? MY81 featured 2 vastly different injection systems. On the US '81 (L-jet/AFC), it is going to be imperative that all of the vacuum controlled components are in good working order & that sufficient vacuum is achieved. A vac leak can cause sudden stalls.

Need to know more about your symptoms. When the car died, will it start right back up? Are there are any other indicators to suggest that problem could be an electrical issue? Perhaps connectivity.

I would replace the large ground strap at the battery & strongly suggest to clean all of the ground points as well. Also, Rich's suggestion to clean up the CE panel is a 928 must-do.
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New to the Houston 928 community - Car stopped running 06 Oct 2017 20:04 #20012


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I really appreciate the information. I (really) enjoy learning as much as possible about the car I love.

As for symptoms during failure. After driving for about two hours, the engine “just stopped running.” I was driving on Hwy 225 at about ~75 mph and the engine cut out, no sputtering, jerking or backfire. The car is a manual, so I put it in neutral, and costed to the “safest” place. The temperature, oil and voltage were all normal prior to the engine cutting-off.

I tried to restart the engine for the first ½ to ¾ of an hour, but it would never “catch” and I never smelled a gas odor, which I would have expected after trying to start the car for so long a time. After having it towed home and draining the battery, I cleaned the connections and battery posts when I installed the “new battery.” On a side note, I had the battery checked, it should not have drained so quickly, and had it replaced under warranty. After that, I changed out the fuel filter and tried to start the car, with no changed. Then after changing out the fuel pump, she started right-up.

Thinking I had solved the problem, and destine to supplant Ferdinand Porsche, I took her out for a test drive but, after about one hour the car stopped in the same manner.
This time however, after sitting for a couple of hours it started right up. Since then, I’ve been starting it, and running it every few days, and even taking it for short rides “around to block,” just to keep it oiled-up and the battery charged.

Now I have the two relays recommended and am ready to move forward.

I will (of course) take your advice and clean all the connections on the fuse panel. I’m not sure how I can check to see if I have US-spec or Euro injection system. Any leads here on how I can verify which I have?
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New to the Houston 928 community - Car stopped running 06 Oct 2017 20:29 #20013


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Hello Dennis,
We're glad to hear that your shark wasn't one of those swimming due to the Houston flooding. Corrosion is often the cause of these problems where the engine dies after some time running, but will restart after things cool down. I suggest finding all the ground points (where a brown wire screws into the body). The factory workshop diagram shows them as MP (mass punkt or ground point).

An Arizona 928 owner had a similar problem and I worked on his L-Jetronic fuel module and corrected the corrosion problem.
Rich
Membership Chairman
Charter Member
1993 928 GTS Cover Girl
1987 928 S4
1979 928 5-speed rescue
1979 928 5-liter track beast
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New to the Houston 928 community - Car stopped running 08 Oct 2017 16:05 #20015


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Here is a picture of one of the relays removed. It shows significant “heat” damage. Hopefully this was the cause.

Took it out for short two-hour ride and a little. I could really feel the difference in the idle, and “smoothness” of the engine acceleration. It’s hard to put into words.

Thank you all for your help.
Dennis
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