5.3L Quit and Won't Restart...

BillWms01 · April 23, 2003

My 2000 Yukon XL (5.3L) quit without warning a couple of days ago, while going down the highway. I had it towed home, figuring I'd track down the problem. No luck, so far.

I pulled a spark plug to check for spark, and am not getting any. I also tested for fuel at the Shrader valve on the intake manifold, and am not getting any.

I'm thinking it's a cam or crank position sensor failed? Where are these located on this engine?

TIA for the help.

CMNTMXR81 · April 23, 2003

The CKP is behind the starter and requires starter removal to get to it.

It will also require a CKP system variation re-learn after replacement which will require a Tech2.

The CMP sensor is at the top back of the motor (where a distributor would be on an old engine). It may require a "sight shield" removal as well as possibly an intake plenum removal if you don't have the room to navigate back there.

BillWms01 · April 23, 2003

Thanks for the reply. Doesn't sound like a a one-banana job! Are a failure of either one of these fairly rare? I've looked around a bit, and have seen no references to their replacement.

I know on my daugther's Exploder, the CKP Sensor seems to be a relatively common problem (and also a simpler replacement).

CMNTMXR81 · April 23, 2003

For older Vortec 5700's it was a kinda common thing, but I haven't seen a pattern on these new Vortec's yet.

It's a one banana job if it weren't for the CKP relearn procedure needing a Tech2. But anytime you replace the CKP sensor or replace a PCM with a new one, this procedure must be done.

gomer · April 24, 2003

i had this same thing happen to me a week ago on my 99 6 liter. had it towed to the dealer. the problem was the positive battery terminal in the battery broke loose. i had shut the truck off and come back 2 minutes later and turned the key and it looked like my truck was possesed by demons. all my guages were bouncing around very erraticaly.got charged 200 dollars for a battery change. 96 dollars for battery, 50 dollars for towing,70 dollars for labor,20 dollars for checking diagnostics. told the dealer they lost any future buisness of mine. knew i was screwed when i went to pick up "ole red" when i had the only vehicle in the shop and 6 or more mechanics were sitting on tires drinking pop.

BillWms01 · April 24, 2003

Well, since it's still sitting in my driveway waiting on tow to shop (not dealer), I figured I'd try the new battery idea. No luck. Still won't hit a lick. Hopefully the shop will pick it up later today, and track the problem down.

BillWms01 · April 30, 2003

Got the Yukon XL back from the shop today, and it's running again! It took them most of two days to find the problem, a shorted wire feeding the ECM under the dash.

Tab was $128 (not counting the tow and new battery). Not too bad, I guess.

BillWms01 · April 30, 2003

Wait, the saga continues...

Yukon started and ran fine last evening. This morning, it quit again on my wife. (And, coincidentaly it happened in the same place on the highway it did the first time!)

Took key to shop, and they're supposed to have picked it up.

Surely, they didn't just replace the blown fuse and not find/fix the short?

This GMC is starting to be like the Chevy motto, "Like a Rock". It's big, heavy, and just sits there quietly. ???

BillWms01 · May 7, 2003

The last chapter (hopefully)...

The Yukon's running again. The shop spent three days tracking down the problem. Finally had to drop fuel tank, and pull the fuel pump and gas gauge sending unit to track those wires. The problem was where fuel pump power wire and gauge sending units terminate at the fuel pump. The pump has some sort of spring-loaded (three springs) between the mounting flange and the pump body. When it's installed, the body rests on the bottom of the tank and the springs are compressed. (I've never seen one like this, and don't know why it's got the three springs).

Anyway, the wires terminate between the flange and body, and they had rubbed together enough to finally rub the insulation off, and short out. It was blowing a fuse in the fuel pump circuit when the truck would hit a certain rough spot (RR crossing). Weird.