Ok, I'm baaack!!

I posted a few weeks ago about my 928 that wouldn't start. Well, it still won't do anything. For reference, it's an '85 with a 5sp. So far I've replaced the fuel pump, pertinent relays and spark plug wires, no change.

One thing I noticed is that the tach doesn't budge when I crank the engine. Could that be an indication that the crank speed sensor is bad? From what I can tell I'm getting no action at the fuel pump and no spark so it seems like something is keeping the computer from turning on.

Thanks for any help, much appreciated as always. It's spring and I want to GO DRIVING!!

Thanks again! - J

 

I know this sounds stupid, but did you quadruple check all of the fuses? Even when they look okay, they could have bad contact. Trying removing and reinstalling all of them, check for corrosion.

 

yep, pulled, tested with an ohm meter and reinstalled.

Swapped relays all over the place.

Even went so far as jumping 12v straight from the battery to the fuel pump to force fuel into the engine, still nothing.

 

Can you be specific on what happens when you turn the key.
What have you checked?
Did you do a Ether test for spark?
Have you cleaned the battery terminals?
Did you check and open the 14 ppin connector at the hot post?
Did you clean all of the grounds including the one at the battery and the one for the crankcase on the bottom of the engine to chassis?
Have you removed the grounds for the CE panel and cleaned them? Have you removed the connector at the brain to check for corrosion?
Is there any tell tale of water dripping onto the CE panel from the blower box?

If you find corrosion on any fuse/relay it should be opened and the blower box should be resealed.
Lastly what was the last thing you fixed, and has the car gotten wet or had been snowed on??

 

Yep, here's a little more info.

Full background: The car was driving fine and about a year ago started randomly not starting after I'd shut it off. It was binary, if it wasn't going to start it just wouldn't start. Come back the next day, fine. Then one day the car shut down on me while driving, just turned off. Couldn't get it to restart but by the time that I got back with a trailer to tow it, it started just fine. That was about when I parked the car in the garage.

Hadn't touched it since until about a month back. Battery was flat dead, like zero volts, so I replaced that and cleaned the cable ends. No love, not even a rumble.

Got back in the car a week later and turned the key for kicks, it fires right off. Ran a little rough and smoked up the garage pretty awful but it was running.

Came back the next day to pull it out and let it run a bit, again, no fire. By this point the car and I are barely on speaking terms.

So I replaced the ignition relay, fuel pump, spark plug wires and try to restart it this week and found the battery to be basically flat which struck me as odd since I'd been careful to make sure that there weren't any lights on or anything drawing on the battery. I charged the battery and cranked it over last night, nothing.

So, to answer your questions;

Yes, I did ether test the engine last year and I don't think it did anything, it's honestly been a while though. I could be mistaken.

I'm not sure what the 14 pin connector is, haven't done anything to it, should I?

Haven't gotten under the car or touched the ground strap. I'll probably do that this weekend but the way it was behaving just seemed so binary it didn't seem like a gounding issue. As I said, I'll do that this weekend either way and see if it has an effect.

Haven't checked the connector on the brain, a little afraid of damaging something expensive so I've thus far stayed away.

I haven't seen any signs of water dripping from the blower box. The fuses and relays fight coming out but not more than I'd expect. No real noticeable corrosion to speak of.

The problems started happening really out of the blue, I hadn't changed much in probably six months. Probably the last thing before that was the timing belt.

Two questions;
-is it possible that the alarm is somehow on and drawing down the battery/turning off the brain?
-if the tach doesn't register anything while cranking would that point to an impulse sender?

Thanks guys for the help, I really apreciate it!

J

 

Start with the basics right?

1. Fuel (does the pump run?)
2. Spark
3. Compression

After that, well it gets more complicated...........as we all know.

Next on my list would be sensors. Easy ones to check are the Temp II and Time Temp, procedure is outlined in the WSM 24-17 I think.


Keep us posted, I am sure you will get it.

Shawn

 

Sorry, should have included that bit too, can't hear the pump running. If you put power straight to it still no love.

Hadn't thought about temp sensors, can that disable the car?

thanks,

Joe

 

Check for spark, and tell us what you find.....

 

And do not forget to clean the ground points, especially the thick ground cable under the engine on the passenger side - corrossion there will keep the car from starting, and look symptomatic of alot of other things.

 

open the air cleaner and spray a 2 second burst of ether into the intake hole, crank it see if you have fire. Do this after you have cleaned all of the grounds.
The 14 pin connector is just on top of the hot post connection disconnect the battery B4 working on it. You should open the back of the top portion of this connector and see if there is broken insulation/wires touching. If you dont have a hot post connector cover , then a cover from a 1988 S4 will work

 

Eliminate one step at a time...........if your not sure the fuel pump is working jumper the fuel pump relay pins 30 and 87; the fuel pump should run giving fuel pressure to the engine.

The most common relay on the CE controls many major components including the brains and they're cheap to replace.

If you're sure there's sufficient spark and fuel pressure checks out when was the last time you inspected the brains and their connections?.

 

Dude, What color is the car?

 

If the pump is not running, then the car will not start. If you put 12v to the pump and it still will not run, then the pump is toast.

If your pump is not running the car will not start, did I mention that

MRMERLIN suggest:

open the air cleaner and spray a 2 second burst of ether into the intake hole, crank it see if you have fire. Do this after you have cleaned all of the grounds.

If it starts, well then you have spark.

From what you just mentioned about the FP not running, that is your no-start problem.

Shawn

 

Assuming you are getting no spark:

I'd try these...In no particular order...

1. Ground points. Clean terminals and contact points till too shiney..
2. Computer. Unplug blow out connections. Reconnect. This alone has fixed some non-starting 928s for me.
3. CRANK POSITION SENSOR. This F-ing thing has been an issue for me in the past. Make sure it's seated fully. If its loose and backed out, it is the problem. I have an old cracked insulator spare that works on hand that I use just to swap out and check this item. One time, after replacing all the ignition components....last thing I checked....Started right up.
4. Ignition modules.
5. It's an 85 with dual coils and dist., so It's probably not a coil or coil wire, since it would still fire intermitantly...
6. Ignition switch.

Good luck!

 

Thanks guys,

Regarding the fuel pump, I should have probably been more clear. The pump doesn't run when you crank the engine but if you put 12v to it it will run fine. I just did that to determine if it would run with fuel running to it or if there was more to it.

Bigmac, the car is red. I just noticed you're in AA, where bouts? Car is parked in old west side right now.

Where's the Crank Position Sensor? Can I check the output to see if it's working or is that just a replacement deal.

Thanks again, as soon as I can get her running it's off to the body shop for a fesh coat of paint!

Cheers - Joe