Mark87AT

Well, my '87 S4 suddenly won't start, it almost kicks over but then just dies. It was running fine yesterday. I suspect it is the fuel pump, but really it could be anything. I am going to poke around a bit myself but will likely have to take it to someone. Can anyone reccomend a good mechanic in the Berkeley/Oakland area? And also any suggestions as to where to start looking, such that I might be able to fix things myself would be greatly appreciated. Mark

IcemanG17

Mark
There is several other Rennlisters in the East bay who might be able to help you out, I'm sure they'll respond later.

But if you do want to take it to a shop, Devek is just across the bay in Redwood city, no matter what it is they can fix it...might be worth the extra tow $$.

One quick fix thought...have you checked relays for the LH brain and fuel pump (+ the fuses)..they are the same as the horn relay...might be worth a quick check? Hope you get back on the road soon!

Rich9928p

The first things to check are relays and fuses.

A relay is an electrical mechanical device that enables high current load switching controlled by a small current signal. The Porsche 928 uses relays to control many of electrical circuits. Many 928 are still operating with their original relays, so failures are common. The main relays for1987 1989 engine start are:

Fuel Pump Relay XX Fuel Pump and O2 Sensor

EZK Relay XVI LH and EZK control Unit

LH Relay XXV Fuel Injectors

Starter XIV Starter

[Horn Relay XII Horn]

Note: The horn relay is the same relay type as the LH and fuel pump relay (and starter relay for automatic transmission cars). So if your horn works, the horn relay may be removed from its socket and swapped with these other relays for testing purposes (or in an emergency as a spare). Bridging relay socket position 30 and 87 closes that circuit and removes relay functionality as an issue for testing. To identify the positions for bridging, match the relay pin numbers that are marked on the bottom of the relay to their corresponding position on the relay socket.

I have very detailed no start diagnostics on my website http://www.electronikrepair.com ... look to the diagnostic page

Mark87AT

Wow! thanks for the quick replies and excellent info. I got the car from my Dad a few months ago. He bought it new in '87. The first thing I did was take it to devek for a new timing belt and other stuff. I would certainly take it there, but they are about 40 miles from me and so it would be a long tow, but not impossible. I am mechanically inclined and have tools but have been a bit daunted by the complexity of my shark but already I am totally empowered by your suggestions.

dr bob

>>Mark Burlingame
>>'87 S4
>>Oakland, CA

Mark, your parents did you dirt. If you'd been born Mark Oakland and you lived in Burlingame, you'd be just a few miles from Redwood City and a mere stone's throw from Devek. Sometimes life deals us the poor hands...

SL8GT

Mark,

Do you hear the injectors clicking when you turn the ignition on? If so, might be the brain.

I have a spare if you need to borrow one. Send me your contact info...

John Struthers

Say!
What about that crank sensor thingy?

Bill Ball

Mark:

I'm in the area and would be glad to drop by and troubleshoot this with you if you need another set of hands and eyes.

The usual suspects have been covered already and it is pretty easy to rule out/in the relays and fuses follwing the above information, then move on to the more serious stuff. The LH brain is a common failure point, and we can swap your brain into my car to rule that in/out.

PM me and we can work out a time.

UKKid35

I borrowed a fuel pump from Jon928se (who took it off his car to lend it to me) to find that when I started to remove mine no fuel spilled out from the tank - Doh!

Mark87AT

Well, thanks for all the help and the "help" I switched out all the relays, and check the pump fuse, then jumpered the fuel pump and it whirred and still no starting... To my great astonishment and gratitude Bill Ball is coming by tonight around six to swap out brains, he didn't think there was much else I could (or should at this point) check before the brain test. M

Mark87AT

Well the good news is that both my EZK and LH units allowed Bill's beautiful white 89 to start nicely, so it's not them. the bad news is I still haven't found the problem! So, I have check the relays and fuses, the LH and EZK, what's next on the list? Mark

Garth S

Mark,
You've got a ton of expert ( and friendly ) help nearby; however, in reading your post, I missed any verification that fuel and/or spark were present at the engine. I must assume that you have checked this prior to delving into relays, brains, etc. .
If not, counter hold and crack open one of the front fuel lines: pressure yea or nay when cranking, or relay jumpered ? Similarly with ignition spark - there is a lot of energy in this system, so be careful. The safe way is to insert one of the cheap neon testers between a wire and the dist. cap ( glow orange with each ign. pulse).
If not already done, it will help focus or communicate your attack.

Bill Ball

I stopped by Mark's place last night. The engine fires weakly. The pump whirs when the relay is jumped, according to Mark, but the car would not start. In the dark I decided to go for the likely items (other than relays and fuses, which he tested before I got there) and pull the LH brain. My car ran fine with Mark's LH. Then swapped the EZK. Again, fine. Mark's battery is very low. A brief jump did not help. Mark stated the battery cable clamp is bad. Rather than fuss any more, he needs to fix that first and get the battery up to full charge. That could be it. Grounds at fuse panel look fine, but should check others. The fact that it fired weakly lead me to believe the crank sensor is outputting, but we need to make a good checklist of the potential causes other than the LH, EZK, fuses and relays. Checking for good spark and fuel would be among them - thanks Garth.

I told Mark that Tony's thread on a similar problem is scary but worth reviewing. I think Tony is still puzzling over his problem, although he changed injectors right before the failure to start, and that may ultimately prove to be it.

heinrich

Bill, you're right. Just a bad battery, and a lot of cranking, can cause it not to want to start. Check spark plugs for fouling.

Bill Ball

Right there, Heinrich. The wires looked good by flashlight inspection last night. Battery is first order of business.