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Quote:
Originally Posted by wcc View Post
^^^ That's a very good idea to have that in the car at all times. I just made my jumper and need to print out the directions because I know I'll forget 'if' the time comes.

Back on topic... So I've read on here somewhere that the AC relays can be used to replace the fuel pump relays. Does that work/apply to our 930s in case of emergencies? I haven't even looked yet...

Are there other work arounds for the other relays? Like the one under the drivers seat? Or are those a must replace situation?

I also need to carry a few spare fuses just to add it to my list.
Yes its the same relay. Still one short if they go both. My 930 is in the shop right now. Probably Airflow Sensor Charging Pressure relay.
Old 07-12-2012, 12:42 PM
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Car Not Start

Thanks to this thread--solved my no start problem. Have had car about a month--after a trip to the mall would not start. Towed it home. Did recommended checks and jumpers--no fuel and no spark. Tracked it down to speed relay under seat---only item I found that would stop both (fuel and spark)--it now runs. Thanks!! I owe many some beer!!
Old 07-31-2012, 09:20 PM
  Pelican Parts Technical Article Directory    Reply With Quote #62 (permalink)
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Quote:
Originally Posted by Shadetree930 View Post
Adding to Mark's excellent response in Post # 12 :

I made a jumper and tested it per his instructions.

The jumper is made from #12 wire soldered at the tips to keep the stray wires under control.

I removed the yellow relay and jumped pins 87 & 87a.



Turned on the ignition and the pumps started right up. OK ..... so we know we can jump the relay.

Next I printed out the instructions (Post #6 of this thread Yellow boost relay issues ) with pin numbers and such. Attached the jumper to the instructions and also taped a couple of toothpicks onto my rescue sheet (to help secure the wires into their holes ... I am a Shadetree mechanic after all).



Put the rescue sheet into my glovebox and I am now good to go in the event of a Yellow Relay Failure.
1. Question about the emergency jumper cable around the overboost relay: how do you know that 12-gauge wire is the right size? Does it matter if I were to use 10-gauge or 8-gauge? Anyone know?

2. Also, what is the round black relay just forward the yellow overboost relay?

3. And the two (sometimes three) bullet fuses just aft the yellow overboost relay? I have three in place in my car. But it doesn't look like one of them (the most inferior of the three--the white one in the pic above) is hooked up to anything. Looking in pictures, some people seem to have the top two (blue) fuses, but the lowest fuse spot (white) is sometimes left blank. What do those three fuses do? Or, rather, what are they supposed to do?
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Old 12-30-2012, 07:54 AM
  Pelican Parts Technical Article Directory    Reply With Quote #63 (permalink)
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Got sick of trying to track the fuel system wiring through all the other noise on the Porsche manual wiring diagrams so killed some boredom and redrew it with fuel system wiring only.
I hope it helps someone.
Just reposting this as I spotted a mistake in the key letters.
Email me if you want this as a clear PDF or Visio file.
Second diagram shows how to bypass these devices if you need to get home.



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Old 04-18-2013, 05:27 AM
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look at the fuel circuit as 2 seperate circuits. one is the 2 FP relays, the yellow relay(contacts), the rev limiter, and the pressure switch. the other circuit is the yellow relay(coil) and the AFM switch. the AFM switch removes ground from the yellow relay, de-energizing it when the engine is running. the FP circuit gets its ground through the contacts of the yellow, then the rev limiter then to the pressure switch. all the yellow relay is doing is energizing the 2 FP relays. the yellow relay is also (?) what gives the 1-2 sec FP run before starting.

short description:
the yellow relay is controled or energized by the AFM switch. with the key on and engine off, the AFM energizes the yellow relay, removing the ground to the 2 FP relays. that ground is of course the boost pressure switch.


the drawing i have for an 86 shows the speed relay or rev limiter side cuts out at 7k, and the other side is for the O2 sensor. it shows it cutting out at 3k. so at 3k the system should go open loop mode.

tim's relay had several broken solder joints. one was on the coil for the FP's. the others where on some of the major pin joints. some even for the O2 side. so for those that have bad relays' pull them apart and just resolder the points i mentioned.
you can apply 12v to pin 7 and ground to pin 5 to test the relay. both relays should pull in.
(i actually used a 9v battery)



here is how i would go about TSing this system: based on whats esiest to do first and each step does not fix it.
(if one pump runs and one does not, then the FP or the relay is bad.)
the letters in () are to go along with the diagram above.

both pumps not running:
i would reach around and pull the connector off the AFM. as soon as the key is ON, no start needed, the FP's should run. (F)
then i would check to see if the boost pressure switch is grounded. with connector off AFM, ground the wire on the boost switch. (A1)
jumper 30 and 87a on yellow relay. (G5)
jumper pins 1 and 2 on the speed relay. (B3)
IF 1 and 2 run the pumps, check for 12v to speed relay. (M pin 7)
if 12v present, speed realy bad. bad solder joints are a problem on this relay.

jumping the FP relays really only lets you know the FP's work.
grounding (D4) just cuts the circuit in half. if the pumps run, then it is something on the left side. if they do not, then it is on the right side.

a note for the yellow relay:
unlike most realys, the yellow relay runs the pump in the de-energized mode, or "normally closed" mode. so the coil can be bad and the pumps can run.
you might consider popping the cover off and cleaning the contacts with fine sandpaper. i bet there are a LOT of good/repairable yellow relays that have been replaced.

the yellow relay and speed relay are known for bad solder joints.

the FP circuit was different for the years on the 930 from what i am told. the 87 has a fuse in the wire bundle itself that feeds power to the speed relay. it is a pain to get to....from what i am told.
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88 BMW 325is 200K+ [__] RUNNING: [__] NOT RUNNING:
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Last edited by T77911S; 07-11-2013 at 04:00 AM..
Old 07-11-2013, 03:57 AM
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Nice thread, thanks
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Old 12-08-2013, 11:03 AM
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So this thread has already helped me! Car turned over no problem, but just wouldn't start. Based off this thread, I pulled the yellow relay off and it just seemed very loose in the plugs, so I put the key to the on position and didn't hear the fuel pumps. I wiggled the yellow relay and the fuel pumps fired to life. I used a small flat blade screwdriver to crimp the female recepticles a little smaller and a razor blade to make the male plugs on the relay slightly larger. It plugs in much more snug now and the engine fired right up!

Thanks guys! Great thread!
Old 12-08-2013, 11:33 AM
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A couple of years ago, my 86 carrera (207hp) don't wanted to start in the morning

A piece of the old clutch had damaged the tdc sensor... Only mechanically, a multimeter showed normal values but the motronic didn't get right information anymore

Lundtauto in Berlin found and fixed it (hat tip to the guys...)

Tim
Old 01-24-2014, 12:49 AM
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83 RUF btr Fuel pump, ignition issue

My car was not getting enough fuel on full boost so I stopped running it up. I think I have one of the fuel pumps out? If that is the issue how do I tell which one is at issue? Where are they? I was told there are two years ago....

The other night I went out and went to restart the car and it would not start. It was running fine before. The battery and oil pressure lights come on but ZERO response to turning the key. I used to hear the fuel pump start but not now.

Any ideas?
Old 07-16-2015, 08:15 PM
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Engine died after run.

yesterday I took my 1989 930 for a run, about 30km, prior to my yearly government road worthiness check (MOT in UK).
Stopped on my drive and the engine just died on me. Tried to restart but it was having none of it, turned over easily but it wouldn't fire. Normally after a run it will start immediately.
Thought it might be yellow relay which I had replaced almost exactly a year ago after similar non starting problem. No affect wiggling it so decided on the well documented jumping 87 & 87a, nothing, this made no difference to anything, I could not hear any difference to the very faint whirring sound I can hear behind the dash when I turn the key on whether the yellow relay is in place or not or whether it is shorted or not.
Checked pump relay fuse in front, cleaned contacts, no difference.
Reading this thread I thought maybe the over speed relay under drivers seat was responsible but I do not appear to have one under either seat. My car is a Euro left hand drive model 1989, is this relay located somewhere else on the later 930s?
Should I be able to hear the fuel pump/s clearly when I turn on the ignition? I am sure it is a fuel problem, the car was going fine during the run, I had stopped many times during my run at traffic lights etc maybe I was just lucky it conked out on my drive.
Can I short out the pump relay so that I can hear it run?
Any advice you could offer would have to be in simple terms as I am no mechanic.
Old 09-09-2015, 07:32 AM
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Quote:
Originally Posted by David930 View Post
yesterday I took my 1989 930 for a run, about 30km, prior to my yearly government road worthiness check (MOT in UK).
Stopped on my drive and the engine just died on me. Tried to restart but it was having none of it, turned over easily but it wouldn't fire. Normally after a run it will start immediately.
Thought it might be yellow relay which I had replaced almost exactly a year ago after similar non starting problem. No affect wiggling it so decided on the well documented jumping 87 & 87a, nothing, this made no difference to anything, I could not hear any difference to the very faint whirring sound I can hear behind the dash when I turn the key on whether the yellow relay is in place or not or whether it is shorted or not.
Checked pump relay fuse in front, cleaned contacts, no difference.
Reading this thread I thought maybe the over speed relay under drivers seat was responsible but I do not appear to have one under either seat. My car is a Euro left hand drive model 1989, is this relay located somewhere else on the later 930s?
Should I be able to hear the fuel pump/s clearly when I turn on the ignition? I am sure it is a fuel problem, the car was going fine during the run, I had stopped many times during my run at traffic lights etc maybe I was just lucky it conked out on my drive.
Can I short out the pump relay so that I can hear it run?
Any advice you could offer would have to be in simple terms as I am no mechanic.
First of all, in a stock 930, the fuel pumps should not run with just the key turned to the on position. That's a safety feature driven by a combination of things (a micro switch on the air flow metering arm in the fuel head, in conjunction with the yellow relay). The pumps aren't supposed to start until and unless the arm is deflected enough during cranking. But with that said, many cars have bypassed that and the pumps run with just the key turned to on. Has that been the case with your car....have you have always heard the pumps run without the engine running, until now?

A distinct possibility is that the single white wire that connects to the overboost sensor switch has fallen off. That too links mysteriously with the yellow relay, and the wire at the over boost sensor provides a necessary ground for the relay to work....and thus the pumps. Find that sensor, it's on the boost recirculation manifold, straight back beneath/behind the intercooler on the left hand side as you face the engine from behind. When you find it, if the wire is still connected, try disconnecting it and grounding it out to the engine somewhere.

And yes, the overspeed relay is a distinct possibility and there should be one under the drivers seat, but then again I don't know crap about Euro '89's. Maybe they put in under the passenger seat just to be Euro-backwards
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Old 09-09-2015, 05:44 PM
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Mark,
Thanks for your help, I shall be checking the sensor switch tomorrow (when I can find it). In answer to your question, I can't say that I have ever heard the pumps running. All I can hear with ignition on is a high pitched whine (not loud) from the rear which I assume is the Bosch electronic s box just forward of the magic yellow relay and a very faint humming sound from behind the dash.
Is the over speed relay flat and rectangular , about 1 inch by 2 inches with a couple of wires at each end? This is all apart from the seat controls that I can find under the driver's seat
I'll keep you posted on the sensor switch.
Old 09-11-2015, 02:16 PM
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Found switch and earthed the wire (or at least I think I did) unfortunately it made no difference.
Still no start.
Old 09-12-2015, 08:07 AM
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I am having a no start issue on my 86 Cali 930. Just did a fair bit of work back there had the entire intake off and everything. Anyway, cranks like a champ, cdi whines, and when I pull off the air box and push down on the metering plate with the key in run I hear the pumps running and injectors singing.

To me this means the problem is somewhere in the ignition after the cdi, and that all the other switches and relays are working fine. Is my logic correct?
Old 09-17-2015, 06:33 PM
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You need to be a little more specific about what work you did. Did you touch the plug wires, distributor cap, wiring harnesses, fuel system? It takes a while to prime the fuel system if you pulled the lines. It is pretty easy to mess up firing order if you pulled the dizzy cap, etc. It's even easier to leave a vac line unconnected. What were you doing "back there"?

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Originally Posted by flightlead404 View Post
I am having a no start issue on my 86 Cali 930. Just did a fair bit of work back there had the entire intake off and everything. Anyway, cranks like a champ, cdi whines, and when I pull off the air box and push down on the metering plate with the key in run I hear the pumps running and injectors singing.

To me this means the problem is somewhere in the ignition after the cdi, and that all the other switches and relays are working fine. Is my logic correct?
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Old 09-18-2015, 02:20 AM
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Originally Posted by DSPTurtle View Post
You need to be a little more specific about what work you did. Did you touch the plug wires, distributor cap, wiring harnesses, fuel system? It takes a while to prime the fuel system if you pulled the lines. It is pretty easy to mess up firing order if you pulled the dizzy cap, etc. It's even easier to leave a vac line unconnected. What were you doing "back there"?
I removed the entire intake down to the heads to replace all the gaskets and seals in the "triangle of death" area and put on a new internal oil cooler. At that time I also did the valve adjustments and put in a new set of plugs, new sound pad, new fuel filter, new BOV seals, new thermo valve, new oil pressure switch, new temp switch, new breather coupling hose, new high amp alternator.......I'm sure there are a few other things I've missed. I have not yet replaced the distributor cap, rotor, coil, or plug wires although I have new for all of them right here. Thoroughly cleaned the engine, compartment, and all components with Coleman fuel, replaced every gasket, o ring and seal on the way out.

Fuel system is fine. Disconnecting top of the fuel filter and pressing on air metering plate results in a fountain of fuel. Like I said, when connected and pressing on metering plate I hear injectors singing. When I first put it together I held down on the plate and you can easily hear as the injectors come on line. Pretty sure fuel system is bled out.

Because I get fuel when I press on the metering plate, that indicates that all the other stuff, speed relays, over boost switches, yellow relays, metering plate switch etc on the fantastically valuable diagram above are working correctly, or at least not an issue here, correct?

CDI whines when ignition is on and for a couple of seconds after its turned off, as it should.

The engine cranks strong. It doesn't fire at all. Doesn't try to fire, doesn't kick, doesn't sputter. Nothing. In my mind, getting the timing off, switching a couple of plug wires, a bad plug, vacuum lines off or swapped, would result in some attempt to fire, or some running albeit very roughly. When I rebuilt my last long block I put the distributor in waaaaaay out and the car started, this is nothing at all.

Last edited by flightlead404; 09-18-2015 at 04:21 AM..
Old 09-18-2015, 03:55 AM
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Ok then I guess you've got it figured out. Good luck
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Old 09-18-2015, 12:37 PM
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Clearly I don't but snarky replies like that don't help at all

Last edited by flightlead404; 09-20-2015 at 07:51 AM..
Old 09-19-2015, 11:05 AM
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Haha... I'm probably the nicest, most laid back guy on this forum bubba. First of all, get off the sticky (hopefully the mods will delete the last few posts). Second of all, telling us you've done everything right doesn't help YOU. The only thing you're right about is that it probably is something simple. Lastly, take your know it all attitude and your 44 noob posts and head back over to sixspeed or one of the other ego forums. Good luck figuring it out.

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Clearly I don't but snarky replies like that don't help at all jag off
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Old 09-19-2015, 11:44 AM
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Haha... I'm probably the nicest, most laid back guy on this forum bubba.
No, that would be me!!!


Quote:
Originally Posted by flightlead404 View Post

To me this means the problem is somewhere in the ignition after the cdi, and that all the other switches and relays are working fine. Is my logic correct?
Since you've verified that you're getting fuel, and that the CDI box whines when it is supposed to, the next thing you might consider doing is disconnecting one of the spark plug leads, putting a spare spark plug in it (ground the plug against some nearby metal) and engage the starter to see if you have spark. If not, it could be that one of the coil wires is not connected, the green CDI-to-distributor wire is disconnected or damaged, or the coil itself is bad.

Last edited by Ronnie's.930; 09-19-2015 at 12:09 PM..
Old 09-19-2015, 12:03 PM
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