Tere had Old Blue out for her monthly run which went fine. After reentering the garage, Old Blue was having a nice cool down idle, and then just stopped. The owner got back in, turned the key and nothing happened. Lights work, horn works, windshield wipers work, heater works, clearance lights work, dash fans work. Battery voltage fine. Power up to fuse box is ok.
Checked grounds, starter solenoid wire, all good.
Suggestions appreciated
Jim

dirty filters?/

May we assume that when you say "nothing happened" the starter would not turn or engage? No indication that it was trying to start? What is "nothing"?

Would certainly be electrical if that is the case. You need to check the coil voltage source, the starter solenoid voltage source, (not the main cable to the starter unless there is a smaller wire from the heavy cable connector) and all other ignition switch operated devices.

without sufficient facts, we are guessing.
My guesses: ran out of fuel; fuel line obstruction

If it cranks but won't start, check the pink (batt) wire going into the distributor. The pink (ignition) circuit should be hot whenever the key is in the on/run position. If not, hotwire it with a jumper to a 12v source and it should run again. (This would indicate a harness or ignition switch problem.) If you have 12v to the distributor and it won't run, the ignition module (inside distributor) is probably fried. (I'm assuming you have HEI ignition, not points)

If it won't even crank, you have lost main power. The big wire on the starter has smaller wire(s) coming off to feed the rest of the engine. Check that connection. This is where the main feeds for the engine harness are connected.

Some of the 454s have an additional magnetic starter switch mounted on the alternator bracket. This switch often is the tie point for several of the "fusible links" that provide power to the engine harness and ignition switch. There are no fuses in the engine harnesses (the fuses are for the accessory feeds, etc) The alternator output often goes through the isolator back to the switch post, then splits to the fusible links.

Let us know more details, maybe I can give you more specific hints. I'll see if I can find some references.

The 86 GM wiring diagram is here:
http://truckroadservice.com/ba.../1986_P30_wiring.pdf

Sorry I wasn't more specific. It was running and then without so much as a hiccup, it stopped. Turning the key produced nothing, no starter cranking, no sound of any kind. Radio will not play and it is dependent on the key. Sounds like the ignition switch is getting no power but why would that happen all of a sudden while it was just sitting there idling?
Jim

I suspect maybe a 12v battery source wire rattled loose while driving, but it stayed running on alternator output. Perhaps when idling the output dropped enough to kill the ignition, then would not run anymore?

Check those main feed wires on starter and starter switch, also check the ignition switch itself for loose harness, good luck.

Could be the ignition switch (your symptoms are common) or the ignition/run relay, which powers up the 12VDC system, including the radio when the switch is on.

If the main battery cables or battery has failed the lights wouldn't work and other items powered by chassis batteries would not work.

On my Breakaway there is a main solenoid relay that is key switch controlled, that has failed on me twice, similar symptoms! Lights and things work but anything ignition switch related was dead



The ST85 solenoid relay is the one I am referring to

The power for the ignition circuit is a direct feed from the ignition switch. (pink wire) There are no fuses or relays in that circuit, it is original GM stuff. The panel gauges also get power from the the ignition switch. In the wiring diagram it is circuit 3, it will be labelled as 3A, 3B,etc followed by terminal location, wire size, and color (pink)

The switch gets power from the main fusible link. Depending on the year, the fusible link is connected to the large post on the starter (solenoid) or on the magnetic switch near the alternator. On my 86 it is on that switch. I think the 85s are the same.

The fuse block down low on the steering column is the original GM panel. Barth added an additional fuse block on the firewall, higher and to the left. This panel is powered by a relay, as Rusty suggested. The ignition circuit is not part of that panel but if that panel (ie radio, etc) is not hot, it does point back to the ignition switch or the main feed as the cause.

Make sure gear selector is in park.

Jim,

Months ago I had a problem with mine stopping and then it would start back up. Then sometimes it would not crank at all.
The problem turned out to be a loose wire on the back of the ignition. Vibration had caused a nut to back off ,almost to the last thread, on the back of the ignition switch.
Hope this helps.

Jim

Old Blue is now starting and running. We traced the problem to the fuse block and after taking it apart, cleaning up some crud, put dielectric grease where needed, put it back together and she started right up. Fixed a couple of other problems in the process.
1. The connection between the starter solenoid and the ignition switch was suspicious at the solenoid. So, we fixed that.
2. Then the HVAC blower motor was wired to an unfused 'aux' terminal on the fuse block. We direct wired it to a 30amp fuse above the radiator and will now buy a new blower motor. Thanks to Steve VWs very nice description, this will be an easy upgrade.
Just a special thanks to my son-in-law Dan, aka jet pilot, rock crawler builder, Camaro aficionado. It took him 4 hours to figure things out. I held the shop light.
Jim

quote:

Originally posted by Jim and Tere:
Just a special thanks to my son-in-law Dan.

It always helps to have"connections" to check your connections...