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Discussion Starter #1
1. Describe the problem you are having in detail:

Truck starts like a cummins. Well in all seriousness, hard starting cold. Hasn't been warm enough for me to try in warmer temps outside yet (been hovering around 5°C since I fixed everything else). Basically huffs white like crazy and misses, for probably 10-15 seconds. Cylinders catch 1 by 1 and then she purrs like a kitten. Starts fine after that.

2. Year of truck/engine. 95 K2500, engine has maybe...6,000kms on it

3. Odometer reading (indicate miles or kilometers).
4. Indicate the model number on the Injection pump (starts DS4 or DB2......). 5521, tried a few different pumps I had laying around, and different timing
5. Indicate if you know if it’s a 1500, 2500, 2500HD, 3500, 3500HD. 2500
6. Do you have an EGR on the engine? (An F or an S engine code 8th VIN digit) No sir, vin "F"
7. Air Filter condition (visual check). Peachy
8. Fuel filter condition (freshly changed, mileage since changed). New
9. Location of PMD/FSD? (ex. on pump/remote over intake, behind bumper).Bumper
9a. If remote mounted, describe wiring harness (homemade or purchased from which vendor). Purchased, tried without harness as well
9b. Indicate the location and condition of the FSD/IP grounding wire. On the pump
10. Outside Temperature (C or F). _____ ° -5 to 5°C

11. Service Engine Light while running?- on/off/intermittent Nope, no DTCs
11a. Service Engine light does glow during start/cranking/bulb check: Yes/No Yep
12.Have you scanned for engine codes? Yes/No Yep
12a. List exact results on engine codes.

13. Condition of Battery terminals (removed, cleaned and tightened).
14. Known condition and age of Batteries. New. Load tested at 475A for 20 seconds, never dropped below 10V
14a. Are batteries a matched set of same age? Yep
15. Condition of Major Grounds (removed, cleaned and tightened) Cleaned, and re-done
15a Have the batteries been individually load tested? ^^

16. Does engine crank, or "turn over"?Mhm
16a. Does engine start and run? Yes Sir
17. If engine does not start- Crack injector line: do you have fuel? Yes/No
18. Does your Wait To Start light come on? Yup
18a.Number of seconds WTS light is lit. ~10-15
19. Engine Cranking speed (if you have an accurate tachometer). 175rpm on the Tech II

20. Are you experiencing Stalling? Nope
20a. Describe the event (upon startup only, down the road, hit a bump, etc...)Doesn't miss a beat once it's started
20b. Do you notice loss of dash or instruments? Nope, but new ignition switch in fall due to cruise/blower/ABS cutting out
21. Check turbo inlet and air filter for obstructions. Could fit a small child through it it's so clean
22. In a no-hot start, pour a bottle of room-temp water on the injection pump. Does it start now?
23. Lift pump test - Describe results. OPS quit for the 3rd time in 2 years after work i will describe, so bypassed that, in the relay box, so relay gets powered any time key is on (do not judge me, it's diesel, it doesn't burn in the best of conditions aha) LP is a year old, shoots diesel to the moon when filter is cracked with engine running, didn't bother with pressure test at that point. It's good.

24. Upon cold start, does the radiator hose get hard quickly? Yes/No Nope
25. Upon cold start, do you have excessive white smoke? Yes/No Yes
26. Do you have excessive cranking time before the engine starts? Yes/No No
27. Have you used the block heater? Does it affect engine starting? (only try for starting problems). haven't tried it yet, sure it will help though, been getting harder to start as it's getting colder outside.
28. Are all glow plugs in proper working order? Yes, each drew about 15A, cold (as they are bosch, and self regulating)

29. During hard acceleration, do you have excessive black smoke? Yes/No No smoke
30. Do you have any unusual exhaust smoke issues? Only when starting
31. Turbo check out - Pass/Fail If I didn't have to listen to that whistle anymore, that'd be great.
32. Indicate fuel that you are using: Bio-Diesel, #2 Diesel, SVO/WVO, other Most likely #1 right now, don't get the option up here in the great white north, pump all change to #1 in fall
32a. If running Veggie Oil fuel setup, indicate details of your conversion (homemade or packaged system).
33. Are you using any fuel additives? If so, please list. Just a lube, don't even remember the brand, non alcoholic, so I can't drink my sorrows away sadly.
34. Upon unscrewing fuel cap, do you have a large vacuum formed in the tank? Yes/No Normal
35. Do you have any service history available that might pertain to the problem you are having? Oooh do I ever. Will write after.
36. Please indicate any modifications to the vehicle that might help us diagnose better. Heath PROM in it, factory one does the same thing

Anyway, a little more specifics on the truck that actually pertain to this:

All started a couple years ago. Truck was getting harder to start. So injectors went in, as well as glows, made it better. Shortly there after, truck was getting hard to start again. Did a compression test: anywhere from 160-320. Leaked the engine, air was coming from every orifice, intake valve, exhaust valve, and crankcase. So. Drove it as such (as truck must run, to pull my rig) for about a year, then pulled the engine and rebuilt it over winter.

Engine was garbage, I saved the camshaft. Yep. Happy days. So, when i initially rebuilt it, (New crank, rods from a donor, New pistons, rings, chain/gears, good used un-cracked block etc) I put a thicker head gasket in it, as I wanted to run some more boost through it, as well as the diamond pre-cup heads. Oh, also new injectors and glows again (both bosch), just because I felt like it. Low and behold, hard to start cold. Compression test follows, and. Fun entails. The machinist did such a great valve job, each cylinder leaked exactly the same, at 40%.

So, truck had to run, drove it as such until 2 months ago. So pulled the engine again, took the heads to a different machinist, they weren't salvageable, so bought new heads. Put stock thickness gasket back in (I just want it to start proper), started much better, but, still not good enough.

Checked fuel system for air, nothing found, put a sending unit in the tank anyway. PMD Failed a couple weeks ago (wouldn't start hot, no smoke), thought I had a "Hoorah" moment. Nope, new PMD and all of my spares still start crappy. So went on to put a used IP I had lying around, does the exact same thing. I had another IP I pulled off a donor engine a few months ago, (this one was a 5521, so figured I'd put it on anyway) put that on and still doing the exact same thing. Smokes white and stumbles cold.

I know that was a lot to read, but there's a lot of history with this truck, and figured I'd give as much as I could. There's probably a few things I'm forgetting as well, such as the 3 PCMs I've tried in it (this was last fall, with crappy worn out 6.5) due to it only commanding 2ms of fuel while cranking (which each PCM did the same thing, or I just could not communicate with it)

Going on about the PCMs though, there could be something there, but cannot for the life of me figure out. Truck is a 95 (vin "S"), but has a 94 PCM in it, according to the part number (which a local diesel shop put in before I owned the truck, so don't even know what it drove off the lot with) every PCM i've tried for a 95, the Tech II will not communicate with (starts and runs, just no comm, even though according to diagrams, pin-out is the same)

Anybody know what the actual difference is by chance with the 94 and 95 PCMs, internally they are quite different visually.

Ok. That's enough for one post. I'll play it by ear here, anything else you need to know, just ask. Just looking for some direction as to where I should be looking, while I still have 2 or 3 hairs on my head.
 

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First off, WELCOME to our forum!

What is compression on each cyllinder now?
15 amps is a lot for a single plug. Slow starting is either air in fuel, bad glow plugs or bad compression.
 

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Discussion Starter #4
First off, WELCOME to our forum!

What is compression on each cyllinder now?
15 amps is a lot for a single plug. Slow starting is either air in fuel, bad glow plugs or bad compression.
Thank you muchly!

It just spikes to 15A, will drop to say 8 or 9 within a second or 2, each plug is the same. Also put what I like to call my "Artificial compression button" (Glow plug bypass) in when I had the old engine in, was the only way I could keep it running, had to hold it for about 15 seconds after it started to keep it going. Doesn't make a difference now.

I haven't actually checked compression on it since I put the heads on it, as it runs SO much better than it ever has, smoother, more power, less smoke blah blah blah.

I want to check compression on it (also afraid to, every time I do I find something else haha), just the only problem being as it's currently only a 2wd, as i have 373s in the front and 410s in the back, we're getting some-what pooped on right now by someone upstairs in the heavens, and need a 4x4 to get anywhere. Kicker is I have the 373s for the front, just gotta get it to my shop in order to put them in... which is also where i'd be doing the compression test :banghead:

What I can tell you though, when I do disable it from starting, each cylinder does sound the same, normally with a bad cyl or two, or varying compression, you can hear that when turning it over.
 

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Discussion Starter #5
How was the injection pump timing set?
Tech II, first pump was 3.5 degrees @ .75 TDCO, now with the 5521, have it set at 3 degrees @ 1.14 TDCO (It's slowly getting cleaned out, it's getting better with the more fuel i keep pouring through it) Initially this one was at 3.5 degrees @ 2.02 TDCO, couldn't even get it close.
 

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I hope you mean -.75... tdco should be negative. ..
 

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Discussion Starter #7
Yes, everything is advanced. If you wanna get technical timing is a negative number as well aha thing probably would barely run, or not run at all, if it was all retarded that much
 

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Yes, everything is advanced. If you wanna get technical timing is a negative number as well aha thing probably would barely run, or not run at all, if it was all retarded that much
Start by installing a clear line from the IP to the return line system to check for air, If you find air bubbles in the line then that's your culprit..:
http://www.dieselplace.com/forum/63-gm-diesel-engines/21-6-5l-diesel-engine/736442-1999-gmc-bluebird-6-5l-td-pmd-resistor-settings.html#post7305306
 

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Discussion Starter #9
Yes, everything is advanced. If you wanna get technical timing is a negative number as well aha thing probably would barely run, or not run at all, if it was all retarded that much
Start by installing a clear line from the IP to the return line system to check for air, If you find air bubbles in the line then that's your culprit..:
http://www.dieselplace.com/forum/63-gm-diesel-engines/21-6-5l-diesel-engine/736442-1999-gmc-bluebird-6-5l-td-pmd-resistor-settings.html#post7305306
I did try that, found no air, other than the air that absolutely refused to bleed from the hose. Confused me, then found out after a small bit of research, nothing should be flowing through that while the engine is running anyway. Fuel shut off apparently stops that from happening. Though I may try and track down a permanent clear piece of hose I can put in there to be positive
 

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Where to begin..


The '94 and '95 PCMs are virtually identical, the proms are very different.
Find and make note (list it here if you need it decoded) the PCMs blue BBC (code), it may not be compatable with the upgraded IPs such as the DS4-5521.
Aside from the early HD high volume/high flow IPs (DS4-5068) that require a dedicated eprom, the rest of the '94 and 95 models used the same PCM and proms (for specific applications) for the light duty (DS4-5067) IP thats been upgraded several times since. All the upgraded IPs are 100% compatable with all '95 models, assuming noones replaced the PCM thinking the OEM is malfunctioning..
Easily, routinely, and often MISDIAGNOSED, the PCM is fairly robust and typically outlives the vehicles usefulness when spared the try and fry approach to diagnostics..
Often, replacing the PCM or IP or other components prematurely or needlessly only compounds the s'ituation, SPECIALLY if theres underlying undiagnosed problems.

I'd suggest you re-install the correct '95 PCM w/ original prom (hopefully you still have it), then perform TDCO again. TDCO is required whenever PCM is replaced..

Then start at the beginning. IF the SCAN tool fails to communicate, suspect your scan tool is incompatable. ALOT of modern scan tools wont communicate with GM's OBD1 diesel models, including most of the tech2 scan tools. Look in the tech2 scan tools owners manual for OBD1 6.5 diesel compatability.. Whats the name and model of your scan tool?
Until then, try using a paperclip (step 3) to perform the OBD System Check.


"OBD System Check"




Glow plugs.. Age of and/or type (9g or 60g or duraterm or) of glowplugs and glow plug relay?
Fitted with a manually overide, if so use it often? Explain how long you pre-glow and do you manually do any post-glow?

Glow Plug System Check


DTC 29- Glow Plug Relay Circuit Fault



Battery- CCA's each? Total CCAs?
Maintaining a minimum of 10.5 volts throughout Startup Mode is important.
For that reason, I suggest using a matched set of batteries with a minimum of 800CCA each totalling 1600CCA before taking ave ambient temp into account that quickly suck the life out of batteries.. Bottom line, when its near freezing, you want a minimum of 1200amps available to most efficiently operate all the systems that are competing for same limited power..​


And I know youve already concluded the lift pmp was good.. But should you want to check using the proper diagnosis...
LINK> Fuel Pump Relay Circuit Diagnosis



This diagnostic aid will actually test a healthy lift pump..
Fuel Injection System Diagnosis
Diagnosis of the fuel injection system includes the following diagnostic steps.
INJECTION PUMP
To check the fuel supply to the injection pump (figure 4-9):
1. Check that the output of the lift pump is correct:
• 1988-1993 Model Year Pumps (p/n 25115224):
• Volume of at least 0.24 liter (1/2 pint) in 15 seconds
• Pressure of 40 to 60 kPa (5.8 to 8.7 psi) (Tee in after filter at pump inlet, running at idle)
• 1994 Model Year Pumps (p/n 25117340):
• Volume of at least 0.24 liter (1/2 pint) in 15 seconds
• Pressure of 3 psi minimum with the engine cranking, the ESO disconnected, and the fuel line open after the filter to an approved canister.
2. Check that the restriction of the fuel filter is not excessive:
• Lift pump volume and pressure should be present at the inlet of the injection pump.
3. Check the fuel entering the injection pump for the presence of air, using a transparent hose:
• If air bubbles appear, check the lift pump suction line for air leakage under a vacuum.
4. Check the quality of the fuel:

• If necessary, use a fuel with a known cetane rating.

Source- DS4 Handbook page 25



Ive seen the best step deep into it, and still not fix jacks s'it in the painful end. BEEN THERE, DONE THAT..
FWIW. Do not under-estimate GMs hugely misunderstood red headed step child. The EFI 6.5TD has kicked the living **** out of GM's best MASTER DTECHS for 20 years and frankly continues to fuel those now infamous PMD Tales to this very day..

Anyhow.. Good Luck..








 

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Discussion Starter #11
Where to begin..


I'd suggest you re-install the correct '95 PCM w/ original prom (hopefully you still have it), then perform TDCO again. TDCO is required whenever PCM is replaced..
I don't have the original PCM, as I said, it was replaced before I got the truck, so no idea what was in it previously, I have tried my original PROM, with the same results.

Original PROM is a BPAA, which from what I can find, is for a 95 Vin "F" truck. Which is what I have. But the PCM is a Standard (Brand, not... stick shift) EM3977, which translates to a Delco 16183977 which is for a 94. Should be a EM2488 or 16212488 for a 95. What the difference is, is where I'm lost. And hopefully you can understand my frustration.

What would be a symptom of a mis-matched PROM and IP? Can't only be a starting issue, can it? Truck runs fantastic other than starting.

Then start at the beginning. IF the SCAN tool fails to communicate, suspect your scan tool is incompatable. ALOT of modern scan tools wont communicate with GM's OBD1 diesel models, including most of the tech2 scan tools. Look in the tech2 scan tools owners manual for OBD1 6.5 diesel compatability.. Whats the name and model of your scan tool?
Until then, try using a paperclip (step 3) to perform the OBD System Check.
It's a genuine Tech II, also have a couple Genysis and Mentor scan tools, as well as a launch X431 Tool. All would not communicate as soon as the 95 PCM was dropped in. I know for sure the Tech II works on a 95 vin "F" 6.5 K2500, as a customer had the twin to my truck, about a year ago, and brought it in for some work. I had no trouble with his. He totalled it a few months back, and asked if I could rob the PCM out of it to try it, but he'd already sold it.

"OBD System Check"



Glow plugs.. Age of and/or type (9g or 60g or duraterm or) of glowplugs and glow plug relay?
Fitted with a manually overide, if so use it often? Explain how long you pre-glow and do you manually do any post-glow?
Glows are duraterms, new, even though the old ones were pretty much new, when I rebuilt the engine. I used to use the override all the time with the old engine, it's the only way I could get it to stay running, had to keep it held for 10 or so seconds after it started. I don't use it at all anymore as it makes no difference in starting. I've tried giving it an extra 20 or so seconds over what the PROM is giving it, as well as holding it for 10 or so extra seconds after it starts, no difference. I've checked the glow system probably 10 times over the course this, every time I checked, they all work and draw the same power.

Battery- CCA's each? Total CCAs?
Maintaining a minimum of 10.5 volts throughout Startup Mode is important.
For that reason, I suggest using a matched set of batteries with a minimum of 800CCA each totalling 1600CCA before taking ave ambient temp into account that quickly suck the life out of batteries.. Bottom line, when its near freezing, you want a minimum of 1200amps available to most efficiently operate all the systems that are competing for same limited power..​
Load tested batteries @ 475A for 20 seconds, never dropped below 10V. Means they're actually stronger than what they're rated at. Load test should be done at half CCA. Cranks over at 175rpm, so batteries and starter are all in good working order.

This diagnostic aid will actually test a healthy lift pump..
Fuel Injection System Diagnosis
Diagnosis of the fuel injection system includes the following diagnostic steps.
INJECTION PUMP
To check the fuel supply to the injection pump (figure 4-9):
1. Check that the output of the lift pump is correct:
• 1988-1993 Model Year Pumps (p/n 25115224):
• Volume of at least 0.24 liter (1/2 pint) in 15 seconds
• Pressure of 40 to 60 kPa (5.8 to 8.7 psi) (Tee in after filter at pump inlet, running at idle)
• 1994 Model Year Pumps (p/n 25117340):
• Volume of at least 0.24 liter (1/2 pint) in 15 seconds
• Pressure of 3 psi minimum with the engine cranking, the ESO disconnected, and the fuel line open after the filter to an approved canister.
2. Check that the restriction of the fuel filter is not excessive:
• Lift pump volume and pressure should be present at the inlet of the injection pump.
3. Check the fuel entering the injection pump for the presence of air, using a transparent hose:
• If air bubbles appear, check the lift pump suction line for air leakage under a vacuum.
4. Check the quality of the fuel:

• If necessary, use a fuel with a known cetane rating.

Source- DS4 Handbook page 25


Well, technically I did a volume test while not intending to do so. I had roughly 120 liters in the tank when I wanted to try a sending unit in it, thinking it could be air, so I used the lift pump to drain the tank. Filled 6 20liter cans in 45mins. Had a hose on the filter and the drain, to double productivity aha So quick bit of math states 2.66 liters a minute. Which is well over the 1 a minute stated above. Pressure I'm sure will be good, but, I can check that anyway, I'll bring home a gauge with me after work tomorrow to verify it.


Ive seen the best step deep into it, and still not fix jacks s'it in the painful end. BEEN THERE, DONE THAT..
FWIW. Do not under-estimate GMs hugely misunderstood red headed step child. The EFI 6.5TD has kicked the living **** out of GM's best MASTER DTECHS for 20 years and frankly continues to fuel those now infamous PMD Tales to this very day..
Anyhow.. Good Luck..
Tell me about it :banghead:
Really appreciate the help though. I will start re-checking a bunch of things, I'm in the process of building a pop tester for the injectors to eliminate them. As they are under warranty, so I'd like to find out sooner than later if they're my culprit.
 
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