worf928

I agree. Something is shorted. It's factory-installed smoke will soon be vented. And possibly be accompanied by rapid exothermic oxidation.

A voltage-drop test during cranking (without LH killer hooked up) will tell all.

Also, those jump starters typically put out 14+v. That's enough that it can mask a bad/slightly-floating ground to a component or subsystem.

Kevin in Atlanta

+928 on my debugging process!

The LH computer is fine - I used another 87 to test it.

I will pass your advice on to my electrician who is going over the car now.

Kevin in Atlanta

When I bought the car besides the non-start the anti-lock warning is lit with the key on and central warning system brain was fried. Is there a possibility the anti-lock and the non-start are related? I need to look at the steps to diagnose that while my electrician does his thing.

fraggle

If you have your PC Oscope, you can test the tach signal/cps from inside the car by putting a probe in the backside of plug W. I think it is pin 23. You should be able to verify the pin outs in the WSM. That signal goes from there to the tach. The advantage here is you can monitor everything in "as connected" state.

You can also remove the tach from the circuit non-destructively by removing that pin from the connector. Use a pin pusher and no damage will occur, and is easily reversable.

Kevin in Atlanta

Broke down and ordered via Amazon.

bureau13

I suspect your ABS light is a blown fuse (something else may of course be blown as well). When I replaced my blown fuse, the ABS light stays off until I've driven a short distance, at which time I believe the lack of signal (I'm presuming this is due to some severed wires by the left front wheel) is causing the light to come on.

Kevin in Atlanta

While I wait for the oscilloscope to arrive I am going to follow mrmerlin's suggestion and look at the power and ground connections at the fuel pump. I find it interesting that with a strong charging the fuel pump comes on and stays on with the key in the start position and and sometimes pulses when I move the key into the on position just on battery power. I know the PO replaced the fuel pump and cleaned the tank and I see there might be an in-tank pump as well. I did clean the grounds in the spare tire well. Time to get it in the air.

Mrmerlin

if you have an intank pump,
it would be a good idea to pull it out and inspect the short hose as they are know to come apart and then take out the 044 pump.

You can replace the short hose and renew the clamps ,
or just swap it out with a fuel strainer.
NOTE its installed to reduce the vapor lock issue.

If you do have an intank pump pay attention to how it may be wired,
it could be shorted

fraggle

Do you have the official Porsche EZK/LH training and troubleshooting guide? It is a nice essential for situations like this. I've used mine a lot over the years. It has. The best details for troubleshooting and some of the nicest wiring schematics for refence.

Kevin in Atlanta

Jim's CDs are in the mail.

worf928

Your electrical system has issues.

Duh.

Putting 40A into a system with issues is going to cause more issues if it hasn't already. If you have a known-good fully-charged battery and cannot keep > 11 volts during cranking to the fuse panel then that is the first thing to fix.

Your LH is fried or someone has wired a bypass around the FP relay (I've seen that before.)

Pull the fuel pump relay. Disconnect the LH.

Wait for the CDs to arrive. Use the LH/EZK troubleshooting guide and first figure out why you have no spark. If you don't have spark you will never have fuel - unless FP relay is bypassed. You will certainly never have injector pulses without spark unless your LH is fried. That is how the system is designed.

Once you have spark, then worry about fuel.

Kevin in Atlanta

Worf928 - Agreed. Waiting on the o-scope and the CDs. The computers are fine.

You are probably right - I just need to document what I have. Keeps me busy while I wait for the CDs and o-scope.

Sapientoni

I had one that got water in the system and after the cleaning (of the water removal while hot and subsequent fire damages) the fuel pump was making noise like it was working, but it was frozen and just vibrating. It sounded for all the world as if it were working. Check fuel delivery and good luck.

Kevin in Atlanta

While going through my list I noticed the volts from the 30 to the 87 on the LH Relay is 11.78v and 30 to ground is 12.22v. The other three deadly relays are 12.22v~ from 30-87 and 30-ground. Another interesting thing is that without the computers hooked up the LH 30-87 was 10.78v.

Added: After jumpering the LH relay I get 12.14v at LH Connector pin # 18.
Added: After jumpering the FP relay I get 11.62 at the fuel pump fuse.

worf928

If you have observed that the LH from the sick 928 does not activate the FP relay - and therefore the fuel pump - when connected to a healthy 928 with the key in the on position, then someone has bypassed the 85/86 terminals of the FP relay socket in the sick 928, either directory or indirectly.

If indeed your FP runs with the key in the 'on' position with a known-good LH then that is where I would start: why does the FP relay activate with the key on? (Or perhaps the FP circuit itself has been hacked to bypass the FP relay.)

And that's not right. They should be virtually the same.

Have you done a static current draw test on the battery?

Have you examined all the wiring into the CEL panel plugs?

Have you unbolted and flipped-down the CEL panel to look at the back side?

If there is no obvious sign of damage to the CEL, no 'extra' wires hacked-in to the FP relay, etc. Then one thing to do is to study the wiring diagrams for the LH relay circuit so that you know which CEL panel plugs to disconnect so as to break the circuit into branches. Then you can test each branch by itself.