Massive loss of power and electric gremlins on 930

[Motte]

Hello all,

I am experiencing some very annoying issues recently with my 85 euro 930 and I suspect there are more than one fault to chase and they may not even be connected so I am really scratching my head on this one. Maybe one of you can spot a culprit from my list of symptoms so I can finally resolve the issues.

The car is a stock CIS 1985 Euro 930, 2000 miles since a full rebuild, SC cams, K27-7200, Kokeln long neck IC, Clewett turbo oil scavenge pump, Fabspeed headers and exhaust,Tial 46WG.

Last year I had the alternator replaced as I had the tacho bouncing and car would drain battery and die while driving then no battery power at all. I also replaced the ignition cables and coil. The car ran great and after this and last time I took the car out was in March this year.

Only issue that I have had the whole time is that once in every 10 starts, nothing would happen when I turned the key. Then on next try the car starts fine. Also I noticed the thermo time switch has been disconnected the whole time, also when car ran great.

Then after 2 months of stand still I took her out and suddenly I could not get past 2000 rpm as the car would loose power, sputter and just bog down when under load. I can rev it to redline when car is stationary, but certainly not while driving. I also noticed the speedometer would suddenly bounce, then die, then bounce as well as the oil pressure gauge. This happens both when stationary and while driving.

A weird thing is that the speedo and oil pressure gauge will also bounce when I shift gears while car is not moving. Like they suddenly got a power spike.

Basically all the gauges are affected and acts with some erratic needle movements in synch with the speedo bounce. One second they look normal, then they either die or bounce and then normal.

The car also would not turn off when key removed.

Here is what I have checked/done so far:

• Removed the Kokeln IC and checked hoses etc for leaks, all looks fine (as I could see)
  
• Removed the fuel pump relays one by one, and when removing the front pump relay car dies. BUT when I remove the relay for the rear pump, nothing happens. I also tried to turn the key to on and then install the fuel pump relays one by one. I can hear no change when I do this.
  
• The CDI box gives up the normal whine
  
• Checked the dizzy/rotor/ignition wires, all looks okay
  
• Replaced the coil with the old coil, no change

As you can see from the symptoms listed there are electrical gremlins making my gauges act weirdly together with what seems to be a boost leak or massive loss of power when engine is on load.

Can it be a faulty rear fuel pump, CDI intermittent issue maybe, old wiring, faulty ignition switch, alternator fault (although brand new and was working 2 months ago) or??

Any help that can point me in the right direction would be greatly appreciated:-)

/Morten

[gsxrken]

More than one problem at a time can really be frustrating and complicate troubleshooting for sure.
I'd suggest you put eyes on the back of the alternator and the ground strap that runs to the top of the engine case behind it. I know it's a PITA to pull the alternator but the recent work, and the issues, could be related. There's also a braided ground strap near the transmission mount that could be cleaned or replaced. Lastly there is the negative battery cable. Remove, wirebrush contact areas and replace.

The fuel pumps won't run with the key on unless you disconnect the plug on the back of the airflow meter. If you do that and your rear pump still does not run, that's an obvious issue. But I fought a struggling rear fuel pump that wasn't pulling enough weight and had the same inability to rev under load that you are having. The front pump can fool you by putting out enough pressure that you think your'e ok on your fuel pressure checks, but it can't provide enough flow over time when you're driving.

Lastly, the ignition switch sounds flaky. They're known to go eventually. Do a search on the 911 technical board for more incidences of that sort of thing than the turbo board.
Good luck!

[908/930]

Like gsxrken said, check all battery ground and positive attachment points and also clean battery terminals. That once in 10 starts that nothing happens can you hear any click sound from the starter solenoid?

[Motte]

Ken,
Thank you for great advice - was really hoping not to deal with the alternator again but guess there's no way round it. I will also check the transmission ground strap and negative battery cable.

So if I remove this plug (if I can get to it) and turn ignition on, should I then hear both fuel pumps?

[Motte]

Regarding the once in 10 starts I am pretty sure there were no sound from starter solenoid.

[908/930]

When you turn on ignition your pumps should run for about 1 sec, at least mine do. Yes if you unplug the sensor switch for the throttle flap the pumps should run with ignition turned on. You should be able to reach around and unplug it.

[Motte]

I am quite sure that I could hear both pumps with a high pitch sound before when I turned the key on and I didn't have these issues. Now I can't hear them.

[908/930]

Check if you have power from your ignition switch.

[Motte]

Thank you, this is helpful. I will try to check for ignition power.

[flightlead404]

Originally Posted by 908/930

Like gsxrken said, check all battery ground and positive attachment points and also clean battery terminals. That once in 10 starts that nothing happens can you hear any click sound from the starter solenoid?

I wouldn't just check them, I'd remove and clean, and reinstall them.

I would also check the two connectors in the engine compartment. One in front of the engine on the cross member and the other in the rear LHS corner on the sub panel.

The pins on those connectors are split and sometimes running a razor blade in the split to slightly spread them will help with connectivity.

There are other grounds as well, check the wiring diag, but the above mentioned ones are key.

[Motte]

Guys I really appreciate your help - the massive loss of power is now resolved....:-)

I started to clean and wire brush all the grounds in the frunk, the battery cables etc. Tested after each step, still had all the issues.

Was looking for the speed relay under the LH seat from the diagramme, but apparently on my 85 Euro there is no such relay. BUT what I did find was an old red fuel pump relay, I cleaned it and then I started to check for power on the fuel pump relays. It turned out that one 1/4 of a pin on one of the fuel pump relays was broken off, so I tried with that old relay I found and bingo - car ran perfectly again. Full boost and no hesitation, so aparently that china relay with a broken 1/4 pin was the culprit:-)

My speedo is still bouncing a little, so now on to that issue but at least the car runs great again.

Again thank you so much to everyone that chimed in, I will update if I find the issue for the speedo bounce - last time it was the alternator, hope this is not the issue again..

[Motte]

The faulty china relay with a broken 1/4 of a pin and the old one I found under the seat

[flightlead404]

Originally Posted by Motte

Guys I really appreciate your help - the massive loss of power is now resolved....:-)

I started to clean and wire brush all the grounds in the frunk, the battery cables etc. Tested after each step, still had all the issues.

Was looking for the speed relay under the LH seat from the diagramme, but apparently on my 85 Euro there is no such relay. BUT what I did find was an old red fuel pump relay, I cleaned it and then I started to check for power on the fuel pump relays. It turned out that one 1/4 of a pin on one of the fuel pump relays was broken off, so I tried with that old relay I found and bingo - car ran perfectly again. Full boost and no hesitation, so aparently that china relay with a broken 1/4 pin was the culprit:-)

My speedo is still bouncing a little, so now on to that issue but at least the car runs great again.

Again thank you so much to everyone that chimed in, I will update if I find the issue for the speedo bounce - last time it was the alternator, hope this is not the issue again..

If you want some adapters that replace the round relay base with one that accepts a square automotive type A, just pm me

[M5guy]

I replaced the reds with Bosch 4 pin relays. I also have each relays power source on separate fuses instead of just one for both. All in about a $25 mod, IIRC.

[mark houghton]

Originally Posted by Motte

Guys I really appreciate your help - the massive loss of power is now resolved....:-)

I started to clean and wire brush all the grounds in the frunk, the battery cables etc. Tested after each step, still had all the issues.

Was looking for the speed relay under the LH seat from the diagramme, but apparently on my 85 Euro there is no such relay. BUT what I did find was an old red fuel pump relay, I cleaned it and then I started to check for power on the fuel pump relays. It turned out that one 1/4 of a pin on one of the fuel pump relays was broken off, so I tried with that old relay I found and bingo - car ran perfectly again. Full boost and no hesitation, so aparently that china relay with a broken 1/4 pin was the culprit:-)

My speedo is still bouncing a little, so now on to that issue but at least the car runs great again.

Again thank you so much to everyone that chimed in, I will update if I find the issue for the speedo bounce - last time it was the alternator, hope this is not the issue again..

I'm late coming into this discussion so my comments are of little value, but your first obvious sign was when you pulled the fuel pump relays indivdually and found that the car died when pulling one...but not the other. Bingo, one bad relay.These cars will run ok at idle and low load on one pump, but really doggy when you try to get serious on the throttle

[Motte]

(Flightlead404) I may take you up on that offer, thanks will PM you when I get around this.

(Mark) I did actually play around with the relays including testing with a new china one, therefore I didn’t suspect that particular relay. It could be that the pins are just beefier in the old Wehrle relay making a better connection. I will get to do the mod with modern square relays and two separate fuses in the future.

Today i also replaced the shift shaft seal as it was leaking, and while under the car I cleaned the ground strap on the transmission. I also found a connector in the shift tunnel where only one wire was connected. Not sure which cured my dancing speedo, but it is now fixed as well.

Again thanks a lot to everyone who contributed!

[mark houghton]

Originally Posted by Motte

(Flightlead404) I may take you up on that offer, thanks will PM you when I get around this.

(Mark) I did actually play around with the relays including testing with a new china one, therefore I didn’t suspect that particular relay. It could be that the pins are just beefier in the old Wehrle relay making a better connection. I will get to do the mod with modern square relays and two separate fuses in the future.

Today i also replaced the shift shaft seal as it was leaking, and while under the car I cleaned the ground strap on the transmission. I also found a connector in the shift tunnel where only one wire was connected. Not sure which cured my dancing speedo, but it is now fixed as well.
Again thanks a lot to everyone who contributed!

Happy you've got it sorted out! Often takes a lot of perseverance but in the end you have a blueprint in your mind of your car's idiosyncrasies. Side note: I too replaced the shift shaft seal a few years ago. Doable but rather constricted space under there to say the least. Was the only drip I had and can still say the same.