John Speake

There is a fault find section on my website. http://www.jdsporsche.com/fault%20find.html

I don't think you have an LH ECU problem. More likely a relay or flywheel speed sensor.

AO

Ryan, can you verify that you have spark? If you do, then it's not the flywheel speed sensor.

As Jim Bailey says, "Relay, relay, relay... really!"

Make three relay jumpers. Then jumper the LH relay (XXV for 1990), ignition relay (X for 1990), and Fuel Pump relay (XXVI for 1990) by connecting terminal 30 to terminal 87 (look at the relay for the numbers). If the car starts, shut the car off and replace the relays one-by-one, starting the car with each replacement. When the car refuses to start, you've found your bad relay.

BTW, don't leave your relay jumpers installed all the time as this will power those items continuously. I've made a jumper with a switch on it that allows me to switch it on and off from the driver seat.

SteveG

Why are you saying fried? He didn't jump it or spike it and this is new behavior so he didn't fry it. If the relays check out, it could be slow death of the computer which is not unusual for this MY. For the sake of clarity, I'm just trying to define "fry" and I always thought that was a condition induced by some action usu electrical, like charging or welding with the battery connected.

heinrich

Look at the plugs. It is possible the car has the plugs fouled. Just take a look, it's worth it.

RyanPerrella

Steve,

yes your right, i said fried and when i think of fried i think literally fried, smoking and what have you. But as you said i dont think that would have happened to the car, it would have been as you said a slow death.

Thanks for the ideas on the flywheel sensor, i will check for spark, if i have spark that rules that out.

Now to get at those relays, lets see if i can get those out of the way and hopefully thats the problem.

Jim bailey - 928 International

Four out of 5 times when a 928 has stopped running when I was driving it was a ....RELAY the 5 th time it ate a bolt and split a cylinder ....I like when it is just a relay

dr bob

Ryan-

Relay remover is a couple paint can openers from the wall at Home Depot. These are the goodies that look like a combination beer bottle opener and screwdriver with a bent end. You may want to bend the ends a little more. Pull the ground strap, then get the bent ends under either side of the relay base and rock it a little then pull. Thanks to another Rennlister for this perfect solution, by the way. You'll need to carry a couple bucks with you for the openers, BTW.


There is probably a working test LH brain in your area, or at least a car you can swap yours into to test. I have the original in my car still, and know it will never fail because I have a spare from Rich Andrade in Phoenix. Let me know if you are in a pinch and you can borrow one while yours is reworked. Or just call Rich and get one on a bus to Texas.

Also-- Considering the history on your car, don't forget the "stupid stuff", like temp sensor II, the cam position sensors on the pass side, etc, that may have been disturbed during refurb. And the wiring that connects all that stuff.

dr bob

I looked on the list and there's no relay that causes a bolt to be eaten and split a cylinder. If there is such a relay, it probably needs to be replaced!

I guess that old "chew before you swallow" didn't apply to 928 motors?.

RyanPerrella

Ive pulled the horn relay, also pulled the LH relay

I put the relay that was in the LH slot into the horn and the horn works fine, i assume that that is in fact a good relay.

I guess I'm on to the spark to see if thats my problem.

RyanPerrella

Which relay is for the EZK? Andrew you mentioned X and on my fuse chart in the description for X is "Relay X" Is this the ignition?

I took relay X out and put it into the horn socket and the horn worked there as well. Is this relay also ok based on my theory that if i put it into the horn socket and the horn works, then that relay is ok?

RyanPerrella

Jim,

When you said 4 out of 5 times when it stopped running when you were driving it.....I wasnt driving my car. It wasnt running then just died while i was on the road or something. It had run fine, i parked it, came back 2 hours later and it wouldnt run. Does the 4 out of 5 still count?

Mike Frye

Ryan,

I thought it was: replace the fuel pump relay with the horn relay and see if it starts, no?

the flyin' scotsman

Ryan............there are 7 relays on your model year that are the same.

3 of them (horn, defrost, HVAC blower) can be used to check the other more crucial 4 (ignition, fuel pump, LH, starter)



As previously suggested though pull the fuel pump relay and bridge the 30 and 87 terminals. This test verifies that the fuel pump runs and your getting sufficient pressure to the injectors.

RyanPerrella

the fuel pump relay has the same function as do the others? Most of my relays have the "53" on them, my fuel pump relay looks different, i wasnt sure if that was one that i could swap. I will check that now.

I had pulled a plug and it was dry, so i still suspect fueling to be the issue and not spark. Although I have not been able to test wether or not i have spark as i cant see if there is spark and turn the key at the same time.

BRB

RyanPerrella

Ok I removed the fuel pump relay, put it into the horn, the horn worked. Ok so it seems like all my relays are good.

I had a what I would call a jumper key on another socket on the fuse panel, I believe it was for "backup lights"

So i pulled this bridge that goes from 87 to 30 and put it on the fuel pump socket, I heard a small thump from the rear of the car, then nothing. I do not hear the fuel pump at all. I did this the first time with the LH unplugged, so i plugged in the LH and still got the small thud but no mechanical noise common to a fuel pump.

So do i have a faulty fuel pump, whats the concensus?

Whats my next step, remove the pump and try and put power to it and see if it runs or not?

Interestingly I have had an issue since i owned the car when i get around the 40 miles left range for fuel, when i go around a left turn the car cuts out, i assume this to be fuel starvation, could a weak pump be the cause of this? Could this also have in turn contributed to the pump failing completely?

I am told there are two pumps, one right next to the fuel filter, the other inside the tank. I suppose both are dead?

New thoughts?