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Discussion Starter #1
Before my truck would start run for a minute or 2 and die. Would not restart for a few minutes or a few days. New lift pump, 7.9 psi at the IP, 1 used known good PMD, 1 new known good and a new untested. No change. Next step installed new rebuilt IP, thinking the previous rebuilt IP had issues. Now with the new rebuilt IP, it will only idle with high idle kicked on, white smoke (more of a heavy haze) out exhaust and lots of dark gray smoke if accelerated. If allowed to return to normal idle, immediately shuts down. Return line changed incase it was restricted. Fuel sock in tank clear, good volume/pressure at pump and will siphon freely when disconnected from rear of lift pump. Injectors maybe? They are not from a very reputable place I found out after ordering them. With the 1st rebuilt pump it ran for about 200 miles before it started the run for a minute then die.
 

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Fuel haze smoke is an issue...

Either:
your injection pump is seriously out of time,
The injectors are PISSING LIKE CRAZY,
Or you have broken intake lofters/rocker arms...
 
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And it continues

I check fuel for air bubbles, none, connected PMD directly, no change, #9 resistors installed. Here is a video of truck running. Reason I'm leaning towards injectors is the compression rattle is loud, until motor has chance to clear out.
 

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That looks like at least one injector is pissing...
Pull em all and get em popped
 
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Discussion Starter #6
Now I have what may be a stupid question, the ones in the engine now are the infamous marine injectors. I have a set of Bosch 972 injectors, new, that are for a NA 6.5. Can I use them and would I see much difference between the 2? I'm not looking to blow black or heavy haul. Most I might do now days is load up the bobcat once or twice a year, rest of time looking for reliable everyday driver.
 

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Now I have what may be a stupid question, the ones in the engine now are the infamous marine injectors. I have a set of Bosch 972 injectors, new, that are for a NA 6.5. Can I use them and would I see much difference between the 2? I'm not looking to blow black or heavy haul. Most I might do now days is load up the bobcat once or twice a year, rest of time looking for reliable everyday driver.
N/A injectors are different than standard turbo injectors.
They are "turned down" with a lower pop rate and Nozzle IIRC, to accommodate for the lack of turbo on the N/A engine.

I would stick to using the standard 6.5L Injector
 
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You can get an injector shop to modify that NA injector into Turbo Injector assuming it is using the same thread and it has good injector nozzle (not chinese made).
 

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Marine injectors are good for marine applications where the rpm and fuel rate are relatively stable (meaning light fluctuation) vs highway use where you're at idle, then you find yourself at 1000-2100,2500. Variable rpm fluctuation all the time.

The marine injectors are also ment for 18:1 cr. The OEM cr is 21.5:1

:ditto:

Stick with the standard injectors. Jmj is correct, you can find an injector shop to adjust and pop test the injectors.

Most certified stanadyne dealers/service centers also adjust, reman and pop test injectors.

Find one local to you...
https://www.stanadyne.com/dealer-locator/

:thumb:
 

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Marine injectors are junk. You can use the NA injectors , the pressure is just a tad low but they will work fine. They can be up-graded by having a Fuel injection shop add shims to increase pressure.
The pressure will not effect anything. They might prematurely wear out but I would not worry about that.

Side Note > High pressure does not equal more power so don't worry about that.
 

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Discussion Starter #11
About ready to torch it....

Recap: Old IP, which is actually a new rebuilt, truck would start easy, run smooth, after a 1 -2 minutes would die, would not restart for a few minutes to a few hours, changed PMD...same thing, no difference. A new rebuilt IP, truck hard starting, long crank, try to idle, dies, restarts quicker, but still dies, white haze at high idle, blackish gray smoke when reved, swapped out injectors, no change. No air in return line, ran timing, 1mm at a time from about 3mm to drivers side to 4mm to passengers side no change. After installing new injectors, got trouble codes for sensor fault on each cylinder, cleared and did not return. Ran injector test, cut out each injector and would have slight miss on each cylinder as expected. Will only stay running with high idle kicked in.
:banghead:
 

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Not sure if it applies to a 94, but did you do a tdco relearn ? Or is that 95 only?
 

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Discussion Starter #13
Solved!! Finally

After a lot of frustration and checking, testing and rechecking, I have finally discovered the problem causing ALL these problems I have been having with my truck. In my 1994 C3500 on the return line there is a small black valve looking thing attached to the steel return line inside the tank. Since I was changing sock, I decided to remove this and inspect. It was plugged solid with junk. Cleaned it out and blew it and return line from motor to tank out, put it back together. It now starts and runs with no smoke, hesitation or hard starting. This valve is black with a rubber disc on side about the size of a quarter.
 

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congrats and thanks for posting the fix
 
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