Bjbpe

The car is a 1987 five speed S4 which I have owned since it was new. Living here in Wyoming, I do not have access to the sort of Porsche-bred mechanics that one might find in California or other types of high-population regions. Generally I have been able to limp along keeping the car reasonably well maintained. There are several service shops where I can get some things fixed but I am afraid I might have run into something that needs a little more introspection.

Some time back I was traveling over a rough rural road (we have a lot of them in Wyoming) and I experienced a sudden loss of power. Fearing that a shut-down might result in a no-start I drove immediately to the shop that usually takes care of the car. It turned out that one of the two ignition coils had broken (from the rough road) and, after replacement, I was back on the road.

I had been having occasional non-start problems before the above occurance and they continued after the coil repair. However, I was able to start the car and drive it home; however, upon arriving home and shutting the engine off I could not restart; it cranks but does not start.

I suspected that I might be dealing with a bad pump fuse even though the fuse did not have a break. One helpful person on this forum suggested that I should coat the prongs with solder to obtain a more secure insertion. This I did and I believe the relay is now driving the fuel pump ok.

At 80 years of age I do not have the sort of dexterity that I used to have and so I turned the car over to one of the shops in Laramie.

So, I now have a fuel pump that is working but the car will not start. If I squirt a little ether into the air cleaner the engine will fire as long as it takes to consume the ether. That's all I can describe right now. I would like to add that the brain was replaced a couple of years ago

To all of the younger owners who have some ideas as to where to look for corrections to this problem, I would appreciate your suggestions. If you know just where to look and what component to address, I would appreciate it if you can give the name of the item and not a nickname as I am too old to understand modern jazz. I appreciate any help you guys can throw my way.

I love Wyoming but there are some drawbacks such as what I just described. Still, living up here in the Rockies at 8330 feet and skiing at 10,000 feet is not to hard to take.

Barney

FredR

Barney,

Now that you are leaving the middle age sector of life and approaching senior citizen status I am sure all the folks on this list will be delighted to help as best they can.

First of all I would recommend that you try to establish the nearest knowledge source in your neck of the woods - someone who does not mind the odd blast to get to your location- hardly a tribulation given your location I suspect. A quick geography lesson on Google Earth suggests your nearest major centre is Denver Co, and I am pretty sure I have seen a couple of listers based there so hopefully one or two heroes will emerge from the ranks.

As to your problem well there are so many things that can and do fail with age and cause no start issues. Based on your post it sounds as though the problem is already halved in that it seems you are not getting fuel so let's take a look at the most likely suspects:

Is the fuel pump running? You need to be sure it is running- as you try to start the car ask a youngster to stick his head under the back of the fuel tank - he should be able to hear the fuel pump humming away [it lies just behind a bolted on cover at the back of the fuel tank.

This can fail to operate for two main reasons:
1. -the fuel pump relay is not switching on- try changing the relay from another known good one [I think they are all type 53 relays and there are a number of this type on the central electric board [under the passenger foot board] that are not required for the car to run [lighting circuits for instance].
2. -the fuel injection computer [the LH unit] has failed [a very common failure]. This unit has a secondary circuit board that is infamous for packing up- the computer itself is usually OK but this board is used to switch the fuel pump on. If you replaced the LH unit earlier what did you replace it with- a new one, a rebuilt one or a second hand one? Either way any of these possibilities could fail again but I would be suspicious if you used a second hand unit.

Once you have established that the fuel pump is running the next test at this point will be to check for fuel pressure but let's eliminate the above before we go further.

Regards

Fred

daveo90s4

Hi Barney,

Worth checking that the small red wires that connect to a T bar on the positive battery terminal are all nic a tight.

My Vargas siar symptoms and Greg advised as above, and that immediately solved my no-start problem


Good luck

Dave

outbackgeorgia

Barney,
I also have an 87 S4 so I can at least give you a little history of experience with this particular model.
Also while earlier models have a myriad of fuse issues, the 87 on panels have much more robust design for fuses and rarely have fuse issues that the earlier panels exhibit.
These are most likely issues ( my experience only), listed in order of most likely. Of course, not having eyes on your car is a disadvantage, but I have experienced the following:
1) Fuel pump relay-replace fuel pump and LH computer relays with new. Simple, cheap.
2) Crankshaft position sensor CONNECTOR. This was my second no start. Note the connector failed. I still have the original sensor. I just spliced the wires to eliminate this failure prone connector. The sensor is just a magnet and coil and rarely fails.
3) Mass Airflow Sensor(MAF)- replace with rebuilt one, it will fail due to cycling of the platinum sensor wire. Not a design flaw, just a limited life item due to the burn off cycle at shut-down. This is why it will run fine, then not restart. It can be tested by unplugging the connector, the car will start, but run good only at medium RPM due to fixed default injector cycle.
4)Fuel filter-replace, seems obvious, but can get plugged with junk from fuel debris. You do not have an in-tank pump, sono worries there
5) fuel pump-replace it. It is a limited life item also, just wears out. Fuel filter at the same time
6) Coil wires, won't cause a no-start, but arcing is an issue, replace the 2 coil wires. Coils rarely fail.
7) Hall sensor-ignore this for now
8) ignition switch-electrical part only-just replace it. Easy, cheap.dont use a Chinese part, however.
9) LH computer, it will fail due to a custom chip inside with a limited life-rebuilt one from Louie Ott. I believe you have already done this
10) water/debris in gas, this happened to me on. Trip to FL. Drain some fuel and check when replacing fuel filter. Usually will start OK, but depends on how much water
In your case, FROM YOUR DESCRIPTION, I believe it is the MAF (3 above) if the relays are OK.
This is an easy check. MAF is in the center rear of the intake area, after removing the air filter assembly. Cylindrical, with a 5 pin connector. Just unplugs and try a a start.
By now you probably have many other responses, hope this helps.
Dave

dr bob

Barney--

A similar set of symptoms caused me to be stranded once, fortunately at the bottom of my driveway and not further away. The fuel pump was running as I cranked it -- I could hear it. Pulled the car back up the hill to the garage, and for some reason decided to check the fuel pressure first. Not enough. Put a jumper in the relay socket, and full pressure. swapped in a new relay, car ran perfectly again.

Jim Bailey, who was for a long time the resident expert at 928 International (now in his third career as a film and TV star/producer) preaches a mantra "relay-relay-relay" as first step in getting suddenly non-runing cars back to running condition. The three critical relays in the S4+ cars are the fuel pump relay, the fuel injection relay, and the ignition relay. The X-bus relay follows along since it supplies other critical, but not engine-threatening, functions such as lights and HVAC. All of these relays are "53B" type, the easiest to find and the least expensive. There are cheap ones available at your local parts place for instance, but cheap isn't what you are looking for when it comes to critical relays. Roger, 928 International, 928 Specialists and our other suppliers carry Genuine Bosch replacements.

In the meanwhile, as you wait for the care package to arrive from one of them, you can substitute the horn relay into the fuel pump position. It's the same type, and probably hasn't seen the same service that your fuel pump relay has.

I don't have your fuse and relay chart layout handy, but there's one on the door of the central electrics panel, under the carpet at the forward end of the passenger's footwell. Before you start prying relays out, disconnect the battery ground strap at the rear apron, bottom center of the tool panel. Isolate that so there is no available energy at the relays. The relays tend to be stuck securely in the sockets, such that pulling on the relay case will often just pull the cover off. There's a fancy relay tool available, but for the rest of us there's a workaround -- From the local hardware/paint store, a couple paint can lid poppers, oval handle with what looks like a bent screwdriver tip on the end. I bend the partially-bent tip around some more, so it's closer to 90º. Then one on each side of the target relay, wedge the reformed end underneath the base a little, then roll the handles some to pry the relay out by its base. Put the realy that was in the horn socket into the fuel pump socket, and with any luck at all, the car will start right up.

The suggestion to clean the smaller connections at the battery positive terminals is a good one. On your pre-'91 S4, there are several smaller red wires connected to the battery positive terminal, at a stud from the pinch bolt, secured with a small nut and washer. They feed the fuel injectors, the fuel pump, and the cooling fans. Make sure the connectors are clean, and the nut that holds them in place is snug. I use a small brass brush to buff up the terminals, just enough to scrub off any oxicdation but not so much that it takes off the tin coating on those ring terminals. Once assembled and snug, a little Vaseline will help them stay that way.

Hopefully this relatively simple 'fix' will get you going again. Be sure to get the relays ordered, and install them when they arrive. It's no fun getting stranded by stupid stuff like this. For others playing along at home, replace these relays prophylactically, and save yourself the trouble of trying to swap pieces on the side of the road somewhere.

Bjbpe

Thanks to all for their input. Anyone else with more ingenuity that I seem to posess at the moment?

Randy V

Did you try all the previous suggestions first?

OTR18WHEELER

Most starting or running problems with 928s seem to usually be electrical, wether it be an overlooked blown fuse or a bad relay, wires also get brittle after 30 years. Start with double checking all of the fuses, and the relays, the #53 relay is used for several systems, if your horn works, use that relay to test the other #53 relay circuits. Also check any ground straps you can, each coil has a ground strap, maybe one is loose.

Wisconsin Joe

Well, basic diagnostics.

The fact that it runs on starting fluid seems to indicate that spark, spark timing, crank sensor, compression & cam timing are all good (Captain Obvious at your service )

So it's a fuel delivery problem.

Can you hear the fuel pump run when you crank it?
Or when you jumper it?

Do you have fuel pressure at the rails? You can either put a pressure gauge on it or just open the end of the rail (and use a catch can of some sort).

Are the injectors firing?
Can you hear them 'click' regularly when cranking? Or are they randomly clicking when you turn the ignition on (sign of a bad LH).

You can use a noid light (not a slang term, real tool name) to check for injector pulse too.

Note: "You" refers to either you, yourself; or your tech. None of this is difficult, nor does it require any specialty tools.

dr bob

Barney -- swap the horn relay into the fuel pump relay spot and try it, per my instructions above. This is a five-minute effort. If you've been in the battery well recently, snug the small connections at the positive terminal. You'll need to lift the spare out, making this another 5-minute effort. It took me longer to type the instruction than it takes to swap the realy. Humor me, and give it a try please.


You have a lot of friends and supporters working with you here.

Bjbpe

To Randy V:

So?? Do you have a problem with me trying to get as much info as possible. Seems as if you're the one who is off topic!

Randy V

You didn't answer the question.

dr bob

In many "please help me!" threads, original posters sometimes seem to wait as suggestions pile up, looking for that one simple Holy Grail answer, the solution that takes only seconds, costs nothing, and doesn't get their hands dirty. And causes their car to start and run perfectly, also magically solves the lingering overheating problem, causes cold air to flow from the AC ducts for the first time in many summers, plus freezes tire wear and reverses hair loss.

So when someone gets a series of responses, yet comes back looking for more suggestions, it makes sense to ask if you've tried the stuff already suggested. Saves everybody the trouble of typing their previous suggestions over again for you, in case you didn't read them the first time. Or, you could share the suggestions you've tried already, so we know where to pick up the story as we press on.


So, of the previous suggestions, what have you tried so far? And what are the results?

Bjbpe

Doc Bob, Randy, et.al.

Please check my original note. I brought the car to a automotive electrical specialist a couple weeks ago. At 79 and 3/4 years of age, I am having problems crawling around, over and under the car (arthritis does that to you).

So far, they have not produced a fix (hard to find a Porsche specialist in these parts) and, hence, I was looking for all possible ideas that I might relate to them.

I greatly appreciate your input. When you live as far out of town (Laramie) as we do, we don't get into town all that often. Hence, I have printed out the various comments and will be bringing them into town tomorrow.

Barney

Mrmerlin

Barney Thanks, adding that bit of info is always helpful to the many guesses that are possible.
From the info already posted these suggestions should result in a running machine.

BUT in the interest of of covering all the bases,
make sure to replace the 3 running relays and the fuel pump fuse
EZK,
LH,
fuel pump relays.