I have an '89 760 with 235k. About 3 weeks ago I pressure washed the engine to try and find an oil leak. Afterwards, the car started and ran fine for a couple hours. I got home, shut it off, and went to move it 10 minutes later and it wouldn't start. I've found there to be no spark.

I have a friend with an identical car, and we started swapping parts. I swapped the ignition module, the distributor, the coil, and the two relays on the DS shock tower which I seem to remember someone telling me to check if I ever have a problem but don't actually remember what they control. In each case, his car still ran, and mine wouldn't.

Having eliminated those items, what else controls spark on this car? I've checked fuses, and I can hear the fuel pump coming on under the car.

Thanks

 

Do you own a test light? Turn the key to the run position, not start and start tracing the juice. There's 2 separate issues going on w/ electricity here. The conventional battery to coil, coil to dizzy, dizzy to plugs. That's. easily enough tracked by either using an inline spark tester or sticking a screwdriver into each plug boot and holding near block and check for spark while cranking. The second electrical issue is if the injectors are firing. You can buy a 'Noid light for cheap at AZ. Make sure it's for Bosch style injectors...plug it into each injector lead and see if there's juice.

 

I got the noid light, and my test light, and checked. I have a signal at each injector, and power to the coil and the distributor. As I was wiggling the connector at the distributor to get the plug off, I could hear the fuel system pressurizing and then cutting out. It cycled off and on several times, and seemed clearly related to the movement of the plug.

Is there a relationship between the pick-up coil in the distributor and the fuel pump? Maybe I've got a bad wire in there somewhere, though when I swapped my distributor onto my friends car, it started and ran fine, and my car still wouldn't run with his distributor in it.

 

I had to go out of town for work, and before I left I dropped the car off with a local electrical specialist. I've used the guy before, and he's always been really good.

I got home, went to see him, and he says he checked everything he could find (which is all the stuff I had already swapped with my friends car), and everything is good. He suggested that the only other thing would be the ECU. I pulled mine out, swapped it into my friends car, and his car still ran. I put his ECU in my car, and mine still won't start.

So now I've stumped the electrical specialist.

Thre is only one other think that's a little odd, and seriously, I'm grasping for any answer with this one. When I crank my car, there is a strange knocking sound. It's coming from the starter, and when I grab the starter while it's being cranked I can feel something inside hitting the housing.

So...is there some ignition signal that somehow gets sent through the starter when it's cranking, that maybe isn't going through because something inside is broken? Electrical is not my thing, and like I said, I'm grasping at any possible answer now, regardless of how strange.

As always, all thoughts appreciated.

 

I guess your 760 is a six cylinder and not a turbo, right? The n/a cars went to using a crank sensor in 89, at the top of the bell housing straight down from the firewall. That will definitely cause a no start. The starter is unrelated; might be going bad but in and of itself wouldn't cause a no-start.

 

Sorry, I thought I had included the engine info, but I must have missed that bit of info. It's the turbo 4 cylinder.

 

Crank sensor..........