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View Full Version : Suddenly Dead 97 Suburban 6.5L TD



twinter
08-17-2010, 08:37
Hello All,
A couple days ago, my wife was driving uphill on a gravel mountain road. She reported that there was a "thump" (went over a bump or through a pothole?), and then the engine died, right in the middle of the road, on a curve! I drove out to her location to see what I could do. I was unsuccessful in getting it going, so had to call a tow truck. Here is what I found and tried while out there in the middle of nowhere:

Battery is good. The starter motor turns over fine. But there is no ignition. The "wait for glowplugs" light cycles on and off, with corresponding dips by the in-dash voltmeter.

I replaced the fuel filter with a new one. Cranking the starter motor with the air bleed valve open spewed fuel out, so it appears the fuel lift pump is fine.

I reseated both ends of the cable on my remote-mounted PMD/FSD with no effect. I then replaced the PMD/FSD with a spare. Still no good.

I hooked up my OBD-II code reader, but it could not communicate with the onboard computer, even after repeated tries, and reading the manual carefully to make sure I was using the right procedure.

After 2 days, with a cool engine, I still have absolutely no ignition whatsoever: not a cough, snort, or sneeze out of the engine. Just a cranking starter motor.

Previous to this, the engine had been running beautifully for the last year (that's when I remote-mounted the PMD due to frequent stalling).

Any ideas? Do I have a dead computer? What could fail so suddenly without prior warning and completely kill the engine?

Thanks for you help,
Todd Winter

JohnC
08-17-2010, 09:59
I guess I'd start at the PCM and work outward, looking for loose connections, blown fuse, bad grounds....

I think that the fact that the glow plugs and lift pump are not dead points away from a total PCM failure.

rameye
08-18-2010, 16:52
crank position sensor??

if the avenues above bear no fruit...

DaveBr
08-18-2010, 20:25
My OBD code reader does not work on my truck unless the truck is running. I'm thinking that this is an electrical issue. The thump your wife heard may have been a pothole that shook one of your connections loose.

Try checking your fuel shut off solenoid. You should be able to hear it click when you have someone turn the key off and on.

If you hear it working I would crack an injector line and crank the engine to see if there is fuel coming out the loose connection.

If you have fuel that far then I would turn my attention to the dreaded PMD. Got a spare to try on it? PMD Extension cable - Grab a mutimeter and check each connector end to end for resistance just to make sure one of the wires hasn't come out of the connector.