6.5 TD died Not PMD/OPS/Fuel Filter/air/no codes

[peoplesm]

To start my 94 6.5 TD Blazer died with less than 1/4 of gas and would not restart. This is my first time working on one so I am sorry for not being up to speed on all of the terminology and mechanics of a diesel engine.

So the the next day, I got 10 gallons of new fuel from a different station, changed the fuel filter (very dirty), bled the fuel threw the top of the filter, still would not idle long and does not respond to throttle, blew white smoke.

Searched the internet and before making the PMD purchase changed the oil pressure sensor, bled the fuel again at each injector (seemed to help a little) but still 98% hard to idle and nonresponsive to throttle, finally had one time where it did respond and ran it at 1700 RPM for a couple of min and tried to drive it, heard a loud Psssssssss sound at high rpm before it tried to shift and it died 1.5 blocks from my house and would not idle. Towed it back home

Replaced the PMD, checked for codes, no codes only the standard 12.
Checked for air in the return lines, no air

Unplugged the optical sensor and it started right up, no smoking, running rough or anything.

Checked for codes now, and came up with 17,18,35,36,43

took it to a shop today, they told me the same codes, but after clearing the codes and pluggin in the optical sensor, now it is showing the same codes. So they are saying it is definitly the injector pump and I need a new one at 1200+ 600 for install

I am just curious why it was not saying any codes until I unplugged the optical sensor and if they did clear the codes and plug it back in why it would show codes now.

Secondly, I am not willing to pay that much for the rebuilt injector pump.
Is there anything else I should ask them to do while it is at the shop, or take it home, buy a new pump for 700 and install it and have the timing checked afterwards

Also, John C suggested checking the timing when the optical sensor is plugged in, if it is off, what could I do, or what would that mean?

Thank you in advance for any insight!

Kind Regards!
-=- Mike

[gmctd]

17, 18, 43 are OS failure - Hi res, Cam, and Temp, expected when disconnected.

35 IPW short could be from the original stall at low fuel level.

36 IPW long could be the actual failure - wunner if they cleared the DTC's at operating temps, or tried to clear them cold.

Clear the codes , try removing the OS Filter, inserted between the OS connector and the engine harness conector, try another start

[peoplesm]

Thank you for the further explanation of the codes and ideas.

I forgot to mention a couple things in my original post.

I have tried plugging the optical sensor in without the filter and no change.

I am assuming that when they supposedly cleared the codes, plugged the optical sensor back in and checked for codes, that it was cold. The vehicle was there for 3 hrs before I asked them to redo the codes with the OS plugged in because originally it did not have any codes via the infamous paper clip.

Also checked a couple of the grounds and the connections of the components of the IP.

Also if anyone was interested in the louder pssssssssssss sound I noticed that a fair amount of oil was in the front intake of my turbo and seemed to be coming from my crank case. I had already ordered it when I was informed of my error in determining if it was working properly (could blow air threw both ends) anyways, it doesn't make that noise anymore and hasn't sucked any oil yet.

In addition, this engine has over 170,000 and the vehicle has just over 400,000 and no major problems encountered (except replacing the engine) during the entire time of owning it as a farm vehicle!

[gmctd]

Could indicate the OS Filter is failing\failed - substitution is the preferred solution.

Make sure the 6-pins in the OS connector, both Filter connectors, and the engine harness connector all make good contact

DTC 35 is historically symptomatic of low fuel level or failing fuel supply - air or bubbles in the fuel.

Leaves only the DTC36, which can also be caused by low battery voltage or poor connectivity or failing IGN switch.

Remember - that's 170kmi of accumulated oil in the intake, prolly quite normal.

Get a 4' length of clear vinyl 3/8" tubing, push it onto the dipstick tube, place the other end in a bucket of water, crank the engine and observe the tube at idle and 2000rpm - water should rise in the tube ~1-3", indicating no blow-by, system operational. (quick method courtesy of Bill Heath)

If the water doesn't rise, but shows bubbles in the bucket, that's indicative of excessive blow-by - if it blows all the water outta the bucket, prolly time fer a new DMax.............

[peoplesm]

Thank you for the insight into some of the codes and causes!

I will recheck for air in the fuel lines, and for blow by also.

In addition, I was suspecting the ignition switch was going out (my dash lights would go off random times and come back on after a jolt to the steering column) So I have one sitting around, just haven't changed it out.

Odd question about my lift pump though that I have not been able to get a straight answer to.
When I crank the engine over it comes on and after I turn off the engine, I can hear it running still, a fair amount of fuel comes out the top of my fuel filter so I am assuming it has adequate pressure. But I was curious if it is supposed to come on, when I turn my key to the on position (ie prestart when warming my glowplugs) Some people say yes, other say no as long as it is in the park position. I read on here that I could put in gear and turn the key to the on position, and it should run. Mine does not????

Just curious, Thank you!!!!!!!!!!

[joem]

The lift pump runs durning cranking then switches over to the ops when started then lift pump will shut down when oil pressure drops in the motor. You should not be able to turn the key with it in gear. I have a 5 speed and when I crank it with the clutch out it will run.