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New IP installed now P0251 & P0370

B

ByronF

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Location
Louisiana
I have just installed a new injection pump on a 97 Yukon ("New" model for low sulfur fuel from Heath’s Diesel) also replaced all injectors (From Heath) replaced oil pressure switch under manifold wile in there. Replaced fuel filter and confirmed lift pump working correctly as well as bled all air from lines. Truck runs perfect and smooth when started cold, few miles down the road get a SES light with double codes P0251 & P0370 (four codes total each one twice) Once these codes appear cannot be cleared (or at least return instant) and trucks runs very bad stalls, dies, un commanded jumps in throttle, until truck cools down completely then codes clear and the process starts over about the same place down the highway 3 to 5 miles down the road. I have removed the electrical filter in the wiring harness to the optical sensor and plugged direct, installed a clear hose from filter housing to IP to ensure no bubbles and still have the same problems. Engine has all vacuum system removed with a turbo master installed and EGR system removed. Fuel pressure gauge installed at T drain and reads over 5 psi under full throttle slowly drops no lower than 3.5 psi. Last ditch trouble shooting I unplugged the optical sensor and drove the truck with it unplugged and it ran almost perfect, other than a few jumps here and there near some shift points that would go away with letting of the throttle a little and getting back in after transmission shifts. I do not have equipment to test IP timing only a generic code scanner. Could the timing cause this? Anyone in Louisiana willing to rent me a GM tool to check IP timing? Which tool/Scanner would you recommend (cheapest) Any other trouble shooting ideas?
 
How did you set the timing when you swapped the IP?,
Even if done with the KOKO method you need to verify with a scantool if it is within the perimeters.
 
Thanks for the reply I set the alignment pin at 12 o’clock position when old IP pump removed and went in with new one. Also the old IP had a scribe mark new one did not so I carefully transferred the scribe mark on bolt flange. My scan tool will not show timing info. Will out of fine tune timing cause this severe of problems? Seems odd also that it will fire up great and smooth as can be when cold for a couple of minutes then goes to crap!
 
Could be timing related. PO251 and PO370, what exactly do these codes translate too? IF it is timing related, there is a good chance that once the engine reaches a set operating temperature that the cold advance solenoid is turning off and the pump is "physically" timed incorrectly. Keep in mind, 1mm is equal to about 2 degree's of timing (on a 6.5L) as far as the pump is physically concerned, so "very carefully" transferring the alignment mark from the old pump to the new may be throwing your timing off enough to make the truck run like it is.

You need to get ahold of a real scan tool that will provide a live data stream. (IE an OTC Genisys or Snap on Solus) and use this to determine what your physical timing is.
 
Anyone have opinions on an autoenginuity scan tool little closer to my price range since I have no contact to borrow one.
 
Since its a 97 and OBD2 you can use Car-Code:
http://www.obd-2.com/

Here is the link to the thread that has all the info you should need including the PDF file that shows you how to check and even set TDCO with it.
http://www.thetruckstop.us/forum/showthread.php?9198-OBDII

This program does require one to have a laptop to use in order to run the program. I suppose you could setup a desktop in your truck if necessary, but that just seems painful. Hope this helps. All else fails you can always bring it to a local shop and see what they will charge to set your timing for you, just make sure its a reputable shop that has had experience with diesels before, especially the 6.5L.
 
P0251 and P0370 are optic sensor codes, more precisely.


Not so much to do with timing, but can be if you've got air in the fuel(you did change the filter after all), a bad optic sensor, and cloudy fuel causing the optic sensor not to be able to "see" it's reluctor wheel.

I had the same codes when my optic sensor was dying and basically only working 1/2 of the time.
 
iamdave0887 said:
P0251 and P0370 are optic sensor codes, more precisely.


Not so much to do with timing, but can be if you've got air in the fuel(you did change the filter after all), a bad optic sensor, and cloudy fuel causing the optic sensor not to be able to "see" it's reluctor wheel.

I had the same codes when my optic sensor was dying and basically only working 1/2 of the time.
Click to expand...

I disconnected the fuel line into IP and put in a bucket and ran lift pump until all air from fuel filter was gone. I also have a clear line installed between the filter and IP to monitor any air and its solid fuel no air bubbles. What are the odds of getting a "NEW" injection pump with a bad optic sensor?
 
ByronF said:
I disconnected the fuel line into IP and put in a bucket and ran lift pump until all air from fuel filter was gone. I also have a clear line installed between the filter and IP to monitor any air and its solid fuel no air bubbles. What are the odds of getting a "NEW" injection pump with a bad optic sensor?
Click to expand...

It won't be the first time.
 
Last edited by a moderator:
ByronF said:
I disconnected the fuel line into IP and put in a bucket and ran lift pump until all air from fuel filter was gone. I also have a clear line installed between the filter and IP to monitor any air and its solid fuel no air bubbles. What are the odds of getting a "NEW" injection pump with a bad optic sensor?
Click to expand...

Who did you get the pump from? Is it brand Spankin' new or a reman?
 
How long ago did you order it before installing it?
Stanadyne outsourced these "New" ULSD IP's to India and, IIRC, the pump cams in the first runs were discovered as, well lets just say they didn't meet the "Quality" standards requested by Stanadyne which led to Stanadyne recalling the pumps thus creating a shortage on the market. One or two could have gotten through like "tested good PMDs" or it is very possible that the Optic Sensors were/are faulty as well as. I uncharacteristic of Bill not to get back with you but he got kinda sick earlier this week or he's away from the shop as he often is... He'll get you squared away.
 
great white said:
Unplug the optical sensor and see if the truck still does it.


Sent from my iPhone using Tapatalk
Click to expand...

If he unplugs the optic sensor the truck will go into limp mode and the light will still be on. My Optic sensor was dying, putting out intermittent signal, and i had the same results if i unplugged it.

same p0251 and p0370 codes, same engine symptoms(hard starting, coughing, stalling, very noisy, no power, etc). You can get an osilloscope and a old OS filter harness and make a "bridge" you can connect the scope to. This will allow you to see the signal the OS is generating. If there's no signal the sensor is dead.

I'd bet money that the OS is your problem. Parts can be defective right out of the box. It does happen. If anything you'd blame Stanadyne not Heath. Heath didn't build/design the IP afterall, Stanadyne did.
 
great white said:
Unplug the optical sensor and see if the truck still does it.
Click to expand...

I know my original post was long but I have unplugged the OS and truck runs almost perfect (other than a couple of surges right as trans is shifting and only under hard acceleration) I am not sure what's normal behavior running without a OS
 
See if you can follow your wiring harness around the intake manifold area. I know putting that lower intake plenum back on can be a real PITA sometimes. Perhaps some of your wiring harness (more specifically the optic sensor wires) got caught and smashed under the manifold when you torqued it down. Wouldn't have been the first time I've seen something like that happen.

You could also try picking up a replacement optic sensor from somewhere like Ebay and seeing if that changes things. Might be able to go to the dealer and order one as well... though, if its like anything else from GM it would probably wind up being cheaper to buy the whole pump :rofl:
 
ByronF said:
I know my original post was long but I have unplugged the OS and truck runs almost perfect (other than a couple of surges right as trans is shifting and only under hard acceleration) I am not sure what's normal behavior running without a OS
Click to expand...

Unplugging the optical sensor forces the PCM to a base table with no modifiers for timing or fuel temperature (the os also does fuel temp).

It sounds like your os is bad....keep trying Heath.

Bill and Todd are probably just really busy as usual. I've always had excellent and quick service with them.


Sent from my iPhone using Tapatalk
 
Try to talk to Bill Heath first. That is a new IP, you would not want to change anything since it is still under warranty.
 
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