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Discussion Starter · #1 ·
I have a 1997 Chevrolet 2500 with a 6.5 turbo diesel at idle it wants to surge and die sometimes and driving down the road it’ll surge a little I have replaced the entire fuel system on it but I have not replaced the injector pump took it to a Chevrolet dealer to have them check it they said the pump was bad could this be the problem or is it the optical sensor in it. I have also replaced the PMD and relocate it and put a new crank sensor in it.
 

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I would first install a piece of clear fuel line on the return side of the Injection pump to help locate any air in fuel issues.
If the line is solid fuel with no air bubbles then I would go through all grounds ( using the link in the 6.5L FAQ page for reference).

When you replaced the entire fuel system did that include tank sock? If so, did you install an AC/Delco diesel tank sock? An incorrect tank sock will cause a fuel restriction
When you replaced the crank sensor did you install an AC/Delco brand sensor or aftermarket? Aftermarket Sensors will cause electrical gremlins.
 

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Discussion Starter · #3 ·
Yes I installed all AC Delco parts I am wondering if it is not the optical sensor any injector pump causing all these problems
 

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1994 K2500 Suburban 6.5 turbo.
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I would first check for air in fuel as ok dually said. If I let my rig sit for a week I get a small amount of air but it works out in 1/4 mile, it might not leak fuel out but could suck air in.
 
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X2^^ Air in fuel can create a lot of issues.
 

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What was replaced when you said "entire fuel system"?
 

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Discussion Starter · #7 ·
Fuel tank sending unit in stock return line and pressure light in the tank fuel pump fuel filter housing high-pressure injector lines injectors glow plugs basically everything was replaced except for the injector pump itself
 

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Fuel tank sending unit in stock return line and pressure light in the tank fuel pump fuel filter housing high-pressure injector lines injectors glow plugs basically everything was replaced except for the injector pump itself
Did you install an AC/Delco diesel tank sock in the sending unit?
The tank socks that come on the units out of the box do not contain the correct sock and will create a restriction
 

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Yes I installed all AC Delco parts I am wondering if it is not the optical sensor any injector pump causing all these problems
Is it setting any codes? P0251 or P0370 are the most likely to indicate a bad encoder. Those are for the Low and High resolution tracks on the data disc, respectively. Just curious why you suspect the encoder, sounds like it could be a PMD/FSOL problem.
 

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I was referring to the Encoder Sensor in the pump which functions as the CAM sensor.

I have also seen problems with new PMDs due to over-torqued mounting screws or faulty extension harnesses.

Are you saying all these issues and no codes are being set?
 

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Yes But the dealer I took it to said it had a bad injector pump
Most mechanics will tell you that because they are not doing a proper diagnosis
The Injection pump is always a goto when things can't be figured out
The Labor is intensive and they can also make some profit off of a pump sale.
Win-Win for them, not so much for you when the symptoms return. Your wallet feels it..
 
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Did you install an AC/Delco diesel tank sock in the sending unit?
The tank socks that come on the units out of the box do not contain the correct sock and will create a restriction
This one. If you buy a sending unit, there is a 200% chance that it does NOT have the correct tank sock (it has Gasser sock). The diesel sock have a valve and coarser while the gasser is just straight sock.

If so, you may want to fix that first since it will clog fairly fast and may cause fuel starvation into the IP and ruining the IP.
 

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did they do a tdc relearn when they replaced the crank sensor?
you can test the crank sensor by unplugging the optical and cranking for 30 sec + and test optical by unplugging crank plugging optical back in
 

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This one. If you buy a sending unit, there is a 200% chance that it does NOT have the correct tank sock (it has Gasser sock). The diesel sock have a valve and coarser while the gasser is just straight sock.

If so, you may want to fix that first since it will clog fairly fast and may cause fuel starvation into the IP and ruining the IP.
I agree with the comments that if you lose supply pressure (for any reason) the IP will suffer and die.

Sock obstruction, or lift pump tired, or obstructions of any kind, can all be detected by measuring fuel supply pressure. It should be 6 to 10 PSI I believe. I have installed a electric pressure sensor in the fuel supply line in the engine compartment, with a gauge in the cab, so that I always have intel on what is happening with fuel supply.

Before I did that, as a quick test, I connected tubing to the fuel drain petcock located just behind the radiator, and ran the tubing under the back of the hood to a pressure gauge duct taped to the windshield. That way you can see supply pressure while you are under way.

Good luck with your new outfit.
 
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I had an EGR valve that would stick open and would give me the same problems you have with your truck. It would miss like crazy when excellerating from idle.
 

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I had an EGR valve that would stick open and would give me the same problems you have with your truck. It would miss like crazy when excellerating from idle.
Just a note:
There is not supposed to be an EGR in a 2500 or 3500 truck which is 3/4 ton or 1 ton trucks, respectively.
EGR is equiped is on 1500 truck which is 1/2 ton truck.

Let's wait for OP to respond on his diagnosis first.
 

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1995 Chevrolet Silverado Z71 6.5 TD
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Whether your pump is bad or not. Make sure to run a 6 oz of lubricity fuel additive and 2 stroke oil each tank. The low sulfur fuel destroys the IP the fuel additive helps to prevent that and the 2 stroke oil is for the injector tips. I use Power Service in the grey bottle. Works fine for me. There are several brands out there to check out.
 
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