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Discussion Starter #1
My '97 K15 refused to start late winter of 2019, and shop was full so it sat outside. I got called out for 8 months so it sat some more. Came home December, shop still full, so Chevy sat some more. FINALLY got some time, so had a look at it. It would crank (now with new batteries) just fine, but no fire. Had already tried my spare FSD when it first quit, so didn't go there. This time, I subscribed to "AlldataDIY" thinking I was getting access to a real manual. Absolute rubbish (forgot about the links to shop manual here) might as well be Haynes or other such generic junk. On the way over here, I did a quick search and found the GM factory diesel injection manual for everything UP to 6.2, but could not find the 6.5 version. What I DID find was the link appearing below. It is a comprehensive and well summarized diagnostic guide by someone who has obviously "been there, done that" with these engines./pumps. Especially nice to have cold hard numbers to diagnose and verify with.


My question for here is: I suspect optical sensor (will test in a few minutes). How critical is alignment? I was going to make some kind of reference line, but what about "calibrating it to the pump" as in the Oregon guide?
 

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My '97 K15 refused to start late winter of 2019, and shop was full so it sat outside. I got called out for 8 months so it sat some more. Came home December, shop still full, so Chevy sat some more. FINALLY got some time, so had a look at it. It would crank (now with new batteries) just fine, but no fire. Had already tried my spare FSD when it first quit, so didn't go there. This time, I subscribed to "AlldataDIY" thinking I was getting access to a real manual. Absolute rubbish (forgot about the links to shop manual here) might as well be Haynes or other such generic junk. On the way over here, I did a quick search and found the GM factory diesel injection manual for everything UP to 6.2, but could not find the 6.5 version. What I DID find was the link appearing below. It is a comprehensive and well summarized diagnostic guide by someone who has obviously "been there, done that" with these engines./pumps. Especially nice to have cold hard numbers to diagnose and verify with.


My question for here is: I suspect optical sensor (will test in a few minutes). How critical is alignment? I was going to make some kind of reference line, but what about "calibrating it to the pump" as in the Oregon guide?
If you are experiencing a no start issue and think it is electrical in nature then try out member Dieselpro's gremlin solver:
Unplug everything listed and attempt to start.
 
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For starting issue, first LOAD test (NOT voltage) the batteries one at a time.
Verify that all cables are good and tight.
Grounds are good.
Verify fuel flow from Lift Pump, this is in that PDF linked.

OS is a sensitive part and should be your last last (did I say) last resort.
 

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Discussion Starter #4
Batteries are new, fully charged.
For starting issue, first LOAD test (NOT voltage) the batteries one at a time.
Verify that all cables are good and tight.
Grounds are good.
Verify fuel flow from Lift Pump, this is in that PDF linked.

OS is a sensitive part and should be your last last (did I say) last resort.
 

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Discussion Starter #5
Batteries new, fully charged. FSD all 3 are good. fuel supply volume and pressure to fuel bowl are good.

Sadly, I thought it was trying to start, but once I took off the air horn and cranked without the Op sens connected, I could feel two cylinders blow back badly. Explains why power was shriking, mileage was sinking and smoking more than normal. I think she's about done. What a shame: thousands of $$ of really good parts (fresh rebuild front end, fresh rebuild on xfr case, new rubber, etc.)
 

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Batteries new, fully charged. FSD all 3 are good. fuel supply volume and pressure to fuel bowl are good.

Sadly, I thought it was trying to start, but once I took off the air horn and cranked without the Op sens connected, I could feel two cylinders blow back badly. Explains why power was shriking, mileage was sinking and smoking more than normal. I think she's about done. What a shame: thousands of $$ of really good parts (fresh rebuild front end, fresh rebuild on xfr case, new rubber, etc.)
Verify cylinder compression next..
 

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Discussion Starter #7
Verify cylinder compression next..
I know I am down two from cranking sound and verified by HUGE blowback in intake manifold. Might just be EGR deposits in intake ports, but no time to diddle with it now.
 

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It may be fuel issue from sitting that long?
What was the problem before you put it at the shop?
What was being fixed at the shop?
 

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Discussion Starter #9
It may be fuel issue from sitting that long?
What was the problem before you put it at the shop?
What was being fixed at the shop?
Problem with no-start was why it was parked last winter. Truck in shop is my F450 that I have been rebuilding engine and modding injection further (going to single shot). Have not been home for a very long time to finish (it gets its turn starting tomorrow). Fresh tank of fuel in the K15 when it was parked. I DO run alternate fuels (thus my concern that optical sensor might be fouled with varnish) but it has been on straight diesel for a year+ before being parked.

I have so much rebuilt and new stuff in the truck, I may seek a rust free runner or non-runner in BC interior to salvage as much of this one as possible. The truck has a LOT of sentimental value as it was the first new truck my best bud had in his vet practice many years ago.
 

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What type of alternative fuel? WMO, WVO, BioD?
You cannot really flush the tank that has been used with "wasted" type alt fuel.

Fresh tank when it was parked, you need to put new fuel or at least test the old fuel to see if there is micro organism grow in there.
Did you put some sort of BioCide with that fresh fuel?
 

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Discussion Starter #11
Light napthenic base stocks - far cleaner and drier than what you can get at the pumps. No biocidal additive in the diesel that was in the tank - we have enough from the bulk plant that it is seldom if ever a concern up here (much of the parking time being far, far below freezing) and no evidence of any bio-slime in filter.
 
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