I bought the truck a little over a year ago off of ebay. (Mistake #1) Heading home from the owner/DEALER the service engine light came on. The truck was not as described to say the least. After getting it out on the highway the Service engine light came on and it seemed to stumble every once in a while. When doing the “paper clip test” it gave code 78 turbo wastegate. I replaced the wastegate solenoid and all vacuum lines. I tried to use it to take the family and the boat to the river and it ended up dying mid trip. I let it cool, it would crank. I drove it back home as soon as I could. I cleaned grounds and replaced where necessary. I purchased “remote mount FSD with heat sync” from SS Diesel that mounts on the intake. (Mistake #2) The wires would not reach the remote mount as indicated and three had to be extended to mount. This seemed to fix the dying but not all of the stumbling. I checked the lift pump. Replaced the lift pump and OPS. The ops was not functioning. It took three tries at AutoZone before buying one at Advance that worked. Later, I intermittently had SEL come on indicating EGR circuit fault. Had problems with another vacuum solenoid. I kept having trouble with the SES light. All three solenoids seemed to work fine. I would remove the vacuum line at the map sensor and vacuum was fine. I eventually checked the vacuum by removing the line from the EGR valve. I was loosing vacuum through the map sensor mounted on the firewall. I replaced the map sensor and eventually had to replace the third solenoid. It seemed I had finally taken care of most of the problems that the truck had when I bought it over a year ago. I introduced bio to the truck and drove it around town for about 3 weeks. I slowly worked it up to b50 and all was fine. It seemed to finally be a dependable truck with no issues and ran great off of the b50. This led me up to about 2 weeks ago when we decided to take the truck for a camping trip instead of the suburban. We took the 1.5 hour trip to are camping destination pulling a boat. The truck handled the trip great with no service engine light. It was the first time in almost a year since buying the truck that no check engine lights came on for such a long drive. I apparently knocked on the wrong type of wood after bragging about it to my wife. After taking my son to the doctor to get a fishing hook removed from his eyebrow, the truck would not start. It would crank up and run but die immediately. It seemed like a fuel issue. After having to tow my truck back to the campground I replaced fuel filter, fuel lines from filter to IP, and lines for filter housing down to the steel fuel lines. The truck cranked and ran idling for about 20 minutes. All seemed well. I decided to drive it around the campground to the bath house to clean up. It died. I could crank it up and it would run sometimes. When it cranked if you depressed the accelerator it would die. Most of the time it would crank and die immediately. I did the paperclip test and found code 19, Crank position sensor and a couple of cylinder imbalance codes I think it was 91 and 98. I could not remove the Crank position sensor in the campground and had to haul the truck and boat back home. The flange on the CPS broke off and the wires eventually pulled out. I tried running screws of different lengths into the wire hole and pulling it out. Pieces of it would come out but not the sensor. I ended up removing the alternator and power steering pump,drilling into it, tapping it, inserting a bolt, and with and unbelievable amount of force pulling it out. The end of the CPS was busted by the time I got it out. It did not appear as though the drill and/or the bolt went all the way through the CPS. It was very close to the end of it though. I replaced the CPS with one from AZ. I disconnected the batteries to clear the codes in the ecm. I checked the codes to make sure they had cleared and got code 12. After cranking I got the same results as before, code 19 and it would start but not run. If it started it would idle but die when trying to accelerate. I tried to crank it without the CPS plugged in and it cranked and ran fine in the limp mode. I checked fuel pressure from T-handle, and cracked fuel injectors to see if oozing fuel. All seemed fine. I checked fuel coming from filter at the inlet line at the top of the IP. It came out fine. I tried another CPS thinking I had got another bad part, same results. I tried a third CPS from advance, same results. It would crank sometimes and idle fine. If you depressed the accelerator it would die. Most of the time it would crank and die immediately. When I unhooked the CPS it would crank eventually and run fine in limp mode. I have drained all fuel from tank, lines, and filter housing and put diesel(no bio), 2cycle engine oil and additive into it. Removed all air from lines and filter housing. I cracked the injectors again, no fuel. I tried checking the fuel shut off valve to see if it was clicking. I checked the voltage across the plug going to fuel shut off valve. When the key was on, it was only 0.8 volts. I tried to check to see if the valve was functioning properly by hooking up a 12 volt source to it, it seemed to click fine. I removed the optic sensor filter. There was no fuel or voltage to the fuel shutoff solenoid. I cleaned all grounds again and tried looking for any trouble with wires. I had checked the fuse box previously. I checked it again and the fuse for the fuel solenoid was shot. I replaced it. Now the truck cranks and dies again. If I remove the CPS wires it cranks eventually and runs fine in limp mode. I tried removing the wires to the optic sensor and replaced the CPS wires. It cranked and ran fine again in limp mode.



0. Describe in detail the problem you are having. Please be as descriptive as possible.
1. Does the engine crank, or 'turn over'? Yes
1a. Does the engine start and run? It starts and dies immediately but dies as soon as it starts. It cranks and runs in limp mode.
1a1. If the engine does not start - Crack injector line (http://www.dieselplace.com/forum/showthread.php?p=2188140#post2188140): do you have fuel? Yes
1b. Do you have a Wait To Start Light & the amount of time (seconds) lit. yes, 4- 6 seconds
1c. Ambient Condition (temperature outside indicate F or C) __92° F
1d. Engine Cranking speed (if you have an accurate tachometer). No Tach
1e. Are you experiencing stalling? yes
1f. If Stalling, describe (upon startup only, down the road, hit a bump etc) Upon startup
1g. If Stalling, do you notice loss of dash or instruments? No.
-note if experiencing stalling,you must indicate PMD location in #24.

1h. Check turbo inlet and air filter for obstructions. Cone filters have lost disk and stopped air to turbo. Stock filter is clean
1.1 Lift pump test (http://dieselplace.com/forum/showthread.php?t=39350)- describe results: 8 psi at T valve
2. Service Engine Light while running?- intermittent code, 19 sometimes 91 and 98
2a. Service Engine light does glow during start/cranking/bulb check: Yes
3. Model year 1995
3a. Odometer reading (indicate if in miles or km) 123,000 miles
3b. Miles on major engine components if been replaced (example Injection pump) Do not know.
3c. Indicate the model number on the Injection pump (starts DS4 or DB2......) ????
4. Have you scanned for engine codes? Yes 19, sometimes 91 and 98
5. List exact results on engine codes (http://www.dieselplace.com/forum/dtc.php): 19 Crank Position sensor, 91 and 98 Cylinder imbalance.
6. Air Filter condition (visual check): good
7. Fuel filter condition: freshly changed
8. Condition of Battery terminal connections: removed, cleaned and tightened
8a. Known condition and age of the batteries. Both batteries test good, and turn the engine enough to start. They are not a matching pair.

8b. Are batteries of differing age or are they a matched set? Different batteries, do not know age
8c. Condition of Major Grounds (http://www.dieselplace.com/forum/showthread.php?t=157085). removed, cleaned, retightened. Replaced engine to frame ground.
9. Upon cold start, does the radiator hose get hard quickly? Yes
10. Upon cold start, do you have excessive white smoke? Sometimes, but rare
11. Do you have excessive cranking time before the engine starts? no
12. Have you used the block heater, and does this effect engine starting? Yes I have use, no it does not effect engine starting.
13. During hard acceleration, do you have excessive black smoke? Not since wastegate solenoid replaced
14. Do you have any unusual exhaust smoke issues? Upon startup white smoke sometimes
15. Turbo check out (http://dieselplace.com/forum/showthread.php?t=39368)- pass/fail
16. Do you have an EGR on the engine? yes
17. Indicate if you know if it’s a 1500, 2500, 2500HD, 3500, 3500HD. K2500 4x4
18. Indicate fuel that you are using: Bio-diesel, and Diesel
18a. If running a VO (Veggie Oil fuel) setup, indicate details of your conversion (homemade, or packaged system)
19. Are you using any fuel additives? If so, please list.
20. Please indicate geographic region you are in: TN
21. Do you have any service history available that might pertain to the problem you are having? No
22. Please indicate any modifications to the vehicle that might help us diagnose better.
23. Upon unscrewing the fuel cap (http://dieselplace.com/forum/showthread.php?t=42338), do you have a large vacuum formed in the tank? Not excessive
24. Location of PMD/FSD (http://www.dieselplace.com/forum/showthread.php?t=39436)? /remote over intake
24a. If remote mounted, describe wiring harness (homemade or purchased from a vendor?) Extended from harness
24b. Indicate the location and condition of the FSD/IP grounding wire. On aluminum heat sync. I have read it is not the best place to have it.
25. Are ALL glow plugs in proper working order as per this thread (http://www.dieselplace.com/forum/showthread.php?t=39182)? Don’t know. I haven’t checked them yet.

Have you tried another good and new PMD on a heatsink?

I plugged it back into the one I left on the pump. It does the exact same thing in either PMD. The old one still worked it just cut out when it got real hot.

If I were a betting man I would bet your LP due to the b50. Bio will clean any junk in the tank and send it through your fuel system. Thus your filter will live a short life and if a chunk get caught in your LP then that is starting to fail. I don't see where you opened up your t valve on the top of your engine to see if the LP is working. all you need to do is open it and turn the truck to on and wait for the wait to start light to go out. during this time you should get a stream of fuel through the t valve tube.

If I were a betting man I would bet your LP due to the b50. Bio will clean any junk in the tank and send it through your fuel system. Thus your filter will live a short life and if a chunk get caught in your LP then that is starting to fail. I don't see where you opened up your t valve on the top of your engine to see if the LP is working. all you need to do is open it and turn the truck to on and wait for the wait to start light to go out. during this time you should get a stream of fuel through the t valve tube.

I did check the lift pump. My thread was already so long I did leave out some details. I did have a solid stream coming from the T Vavle. I hooked up a pressure gauge and maintained 8-10 psi while running. I also checked to make sure I got a good stream after the filter where it enters the injection pump.

If that is the case I would say your pmd is toast. If you wern't running the b50 I would have said the PMD first. A quick test would be to unplug the optical sensor and drive it. It will be in limp mode however if it drives fine w/ no stalling it could be your pump or your pmd. Since running in limp mode bypasses the PMD. You would then replace the pmd and if it clears up great if not it is mostlikely your pump. Oh you will get a code for the os being unplugged.

If that is the case I would say your pmd is toast. If you wern't running the b50 I would have said the PMD first. A quick test would be to unplug the optical sensor and drive it. It will be in limp mode however if it drives fine w/ no stalling it could be your pump or your pmd. Since running in limp mode bypasses the PMD. You would then replace the pmd and if it clears up great if not it is mostlikely your pump. Oh you will get a code for the os being unplugged.

It will run in limp mode with either the OS or the CPS unplugged. I did try the old pmd on the pump. It gives me the exact same results. It seems it would be somewhat different.

It will run in limp mode with either the OS or the CPS unplugged. I did try the old pmd on the pump. It gives me the exact same results. It seems it would be somewhat different.

Since that is the case I think you are looking at a possible IP.

Since that is the case I think you are looking at a possible IP.

Any way to tell? I can't afford to just start replacing parts until she is fixed. I have found a few that had threads that had similar problems but did not identify the problem. Most replaced IP, PMD, Ignition switch, and a list of other things that I can't afford to replace right now. I did a search on the Vin and the IP was replaced at 93,000 miles. She has 123,000 on her now. This doesn't rule out IP but I am hoping it is something else.

Thats why I'll never dump nothing but clean #2 diesel in my truck. Think your saving a few bucks at first, only to spend the savings and likely more replacing IP's.

Id suggest you check the entire fuel system for air leaks. This requires more than a visual look see and it cost next to nothing but time.. The potential savings could be huge!
I suggest you remove both the return line and supply line from the fuel tank.
Plug up the return line with a bolt and install a valve stem (one cut from a bicycle inner tube works great) in the supply line.
Then carefully pressurize the ENTIRE FUEL SYSTEM (minus fuel tank and sender) to 20 PSI. I suggest a hand operated bicycle air pump with built in pressure gauge and clip on hose, might cost $20 bucks at walmart.
The fuel system should hold steady pressure for several minutes, if not the added air pressure will usually force fuel out the leak source making it easier to locate and/or identify.

I dont care what the gurus tell you, its worth doing BEFORE you replace this, that, any and/or everything else. It seems a small air leak in the '95 models will cause havic and often resembles a faulty ECM/PCM, FSD, OS, and/or an IP. Been there, changed all that, yet it still just "shut off".

It seems checking for air leaks not only has a low priority at authorized GM service centers, its also status quo on the .net. However GMCorp thinks its important enough to list it as an Important Preliminary Checks and throughout there FSM. But as usual, its often the last thing that gets checked, cant plug in a scan tool for that.. Usually after they've changed most of the expensive good parts and the problem(s) still exist will they take the time necessary to check for air leaks..
Air Leaks are easily misdiagnosed, unless of course its leaking perfusely.
And before your told "checking for air leaks its a waste of time if the LP is functioning properly," let it be known thats not true. Unless of course they dont count the LP suction (supply line ahead of lift pump) line as part of the fuel system.

Good Luck.

Thats why I'll never dump nothing but clean #2 diesel in my truck. Think your saving a few bucks at first, only to spend the savings and likely more replacing IP's.

Id suggest you check the entire fuel system for air leaks. This requires more than a visual look see and it cost next to nothing but time.. The potential savings could be huge!
I suggest you remove both the return line and supply line from the fuel tank.
Plug up the return line with a bolt and install a valve stem (one cut from a bicycle inner tube works great) in the supply line.
Then carefully pressurize the ENTIRE FUEL SYSTEM (minus fuel tank and sender) to 20 PSI. I suggest a hand operated bicycle air pump with built in pressure gauge and clip on hose, might cost $20 bucks at walmart.
The fuel system should hold steady pressure for several minutes, if not the added air pressure will usually force fuel out the leak source making it easier to locate and/or identify.

I dont care what the gurus tell you, its worth doing BEFORE you replace this, that, any and/or everything else. It seems a small air leak in the '95 models will cause havic and often resembles a faulty ECM/PCM, FSD, OS, and/or an IP. Been there, changed all that, yet it still just "shut off".

It seems checking for air leaks not only has a low priority at authorized GM service centers, its also status quo on the .net. However GMCorp thinks its important enough to list it as an Important Preliminary Checks and throughout there FSM. But as usual, its often the last thing that gets checked, cant plug in a scan tool for that.. Usually after they've changed most of the expensive good parts and the problem(s) still exist will they take the time necessary to check for air leaks..
Air Leaks are easily misdiagnosed, unless of course its leaking perfusely.
And before your told "checking for air leaks its a waste of time if the LP is functioning properly," let it be known thats not true. Unless of course they dont count the LP suction (supply line ahead of lift pump) line as part of the fuel system.

Good Luck.

What kind of symptoms was yours having? I will deffinetly try it? I can't afford all of the other parts at this time.

I hear ya bud.

Started out as "stalling" as if I reached down and shut the ignition off. No bucking, skipping, read no advanced warning and out of the blue, it just shut off.
Happened once or twice every other week, then every other day for a week or so.
Then it became a daily thing and it got hard to start afterwards and was hard to start after anytime it "stalled." It quickly progressed to stalling every 5 minutes or so before I through my hands up, said some colorful language and had it towed to the shop. They found a host of DTC's , so many they said it must be a faulty ECM/PCM. When the new ECM/PCM quickly produced virtually the same DTC's, then it was determined to be a faulty Optical Sensor (new it was), then it was the IP (new it was too). When all that didn't fix it, they started changing all them parts again claiming they all were defective.
40 days and $2500.00 later, after they changed every fuel delivery related component MULTIPLE TIMES, it was doing the same ol BS and spitting out the same ol DTC's.

Long story short, I went and bailed my truck out of GM jail and limped it home.
Using only a paper clip, I found an inop LP (new it was too) due to a faulty OPS which exposed an air leak in the rubber fuel line (new they all were) under the fuel manager/filter. I can only summize that because all that stuff was new, they just skipped over the important preliminary troubleshooting checks outlined in the FSM and started chasing my truck with there scan tool.

i am new to the 6.5l and studying what i can, i am poking around SS diesel supply website. came across this. read thru. i currently have a Dodge w/12v cummins (I count the days till i can get back into a GM, but the 12v Cummins is SO darn reliable), it has what's called an "overflow valve", it is a check valve that holds x psi at the IP - it is on the return to the fuel tank. even though you have pressure going into the IP from the LP, if the check valve at the back end isn't holding it, there won't be enough fuel - INSIDE the IP. also, MPG's will suffer. good luck, this may be a possiblity. just a matter of going thru the list of possiblities.

94+ Fuel Pressure Regulator Valve
Fuel pressure regulator valve for all 94+ 6.5TD trucks using the DS4 electronic injection pump.
http://www.ssdieselsupply.com/images/pixel_black.gifhttp://www.ssdieselsupply.com/images/products/thumb/190--20061204145754.jpg
Go To Larger Photo (http://www.ssdieselsupply.com/product_190_94_Fuel_Pressure_Regulator_Valve.html# anchor_pimage) Model: ssd-1488 $49.99

Fuel pressure regulator valve for all 94+ trucks using the DS4 electronic injection pump. Includes all C/K trucks, Suburbans, Tahoe's Yukon's, Van's, School buses and Hummer H1's.
On the DS4 pump the regulator is built inside the return line fitting. It maintains the required 3-5 psi fuel pressure. It also acts as a check valve to prevent the reverse flow of fuel to the tank while the engine if off.
If your fuel pressure is low, it may be a bad regulator valve. Symptoms of low pressure are stalling, hard starting, and a hesitation or stumble on acceleration.
To check your pressure use our test gauge ssd-242 or permanently mount our ssd-215 gauge kit.
Installs in minutes with basic hand tools.

I checked out the wiring harness near the turbo on the passenger side. The plastic around the wiring harness was melted where the harness had fell against the turbo. This had happened before I had obtained the truck. The wiring harness was zip tied to hold it off of the turbo. I removed the melted shielding and tried searching the bundle of wires for breaks or shorts. The wires wanted to hang together but seperated. The wires were exposed to a great deal of heat at some time. I am trying to make sure that all of the wires from the ecm to the pmd are good. Where can I find a chart that shows where A1 C12 ect are on the ecm? I was hoping to see make sure all of the wires from the pmd to the ecm had not been damaged in that area. I can't afford another pmd to check and see if the old one is bad. I am unsure that the pmd is bad since both the old and remote mount cause the engine to do the exact same thing.
To review:
Truck cranks and dies immediatly
Truck will crank and run with either the CPS or OS unplugged in limp mode.
Lift pump and OPS are working and were checked with a gauge.
The fuel shutoff solenoid has 12volts with key on and clicks as if it is working.

did you check the fuel pressure regulator valve? the ss diesel site states the same symptoms.
jon

I checked out the wires. I found one that had rubbed enough for wires to be showing. I checked all the wires I could from the PMD, map sensor, baro sensor, CPS, fuel shutoff solenoid, and coolant sensor all the way back to the ECM. All showed around .2 to .3 ohms of resistance. I put the PMD ground back on the IP. I pulled the PMD and reset the screws on the transistors. She still cranks and dies. Still cranks and runs if I pull the OS wires or the CPS wires.

I have not checked the Fuel Pressure regulator valve or the return line at the IP. I have not tested the PMD with a known good PMD. I am trying all I can while waiting for the money to replace parts.

I found this in another post.
"Don't know if the CPS is the right one, but heard that you have to do a relearn procedure with a scanner, after changing the CPS."
Will disconecting the batteries be enough to do a relearn or does this have to be done with additional equipment?

Did you move the resistor from the old PMD into the new one? With all that plugging and unplugging of PMD and other components use a flashlight and check the female end of all the harness connectors make sure the contact points are not wide open.
If you can find someone with the same engine plug your PMD into it and see what happens

Thats why I'll never dump nothing but clean #2 diesel in my truck. Think your saving a few bucks at first, only to spend the savings and likely more replacing IP's.

Id suggest you check the entire fuel system for air leaks. This requires more than a visual look see and it cost next to nothing but time.. The potential savings could be huge!
I suggest you remove both the return line and supply line from the fuel tank.
Plug up the return line with a bolt and install a valve stem (one cut from a bicycle inner tube works great) in the supply line.
Then carefully pressurize the ENTIRE FUEL SYSTEM (minus fuel tank and sender) to 20 PSI. I suggest a hand operated bicycle air pump with built in pressure gauge and clip on hose, might cost $20 bucks at walmart.
The fuel system should hold steady pressure for several minutes, if not the added air pressure will usually force fuel out the leak source making it easier to locate and/or identify.

I dont care what the gurus tell you, its worth doing BEFORE you replace this, that, any and/or everything else. It seems a small air leak in the '95 models will cause havic and often resembles a faulty ECM/PCM, FSD, OS, and/or an IP. Been there, changed all that, yet it still just "shut off".

It seems checking for air leaks not only has a low priority at authorized GM service centers, its also status quo on the .net. However GMCorp thinks its important enough to list it as an Important Preliminary Checks and throughout there FSM. But as usual, its often the last thing that gets checked, cant plug in a scan tool for that.. Usually after they've changed most of the expensive good parts and the problem(s) still exist will they take the time necessary to check for air leaks..
Air Leaks are easily misdiagnosed, unless of course its leaking perfusely.
And before your told "checking for air leaks its a waste of time if the LP is functioning properly," let it be known thats not true. Unless of course they dont count the LP suction (supply line ahead of lift pump) line as part of the fuel system.

Good Luck.

Can't you check for air with a clear fuel line before the IP?

Quick update:
No luck chasing wires.
Tried to do the KOKO process to get the engine to do a relearn. It is hard to do a relearn if you can't get it to crank.
I may have problems with the CPS. The one that came out of the engine, in pieces, was 10154687. I have read posts from matuva that he has been unsuccessful in replacing 10154687 with 12557046 and getting the truck to run. I will have to pull the new CPS and check the numbers to compare.

:eek:She still isn't going. Still havn't started replacing parts blindly. Can't afford to. Here is an update on what I have tried.

Put a clear hose from fuel filter to IP, No air in lines.Pulled the screen filter at inlet on IP and cleaned.Checked return line.Rechecked fuel shut off solenoid. It seemed to work properly. I pulled the insides of the Fuel shut off solenoid out and tried. Same same.Tried yet another CPS. Still no luck. All of them have had the same part number 12557046 on them. This is not the same as the original 10154687. Can't find any different part to try.She still cranks and runs sometimes. If you mash the accelerator while it is running it will die when it reaches 2000 rpm +-.

Most of the time it while crank and die immedietly.

Always have code 19 after it cranks, or tries to crank. Sometimes throws an 18 in with it. Oh yeah, Fuel gauge acted funny for a little while when I was working on it. It would peg all the way over. After draining the tank I only put back in a few gallons. She is lower in fuel than I have ever let her get before.

It always cranks and runs fine with optic sensor or CPS unplugged in limp mode.

Other things I am debating trying when cash allows in the order I may try them.
Remove intake. Check all wires from IP, sensors, ect, all the way back to as far as I can check. Remove old PMD while I am in there. Take the resistor out and put in newer pmd and see what happens. Replace return fuel line while I can get to it. Make sure return line is functional. Clean out the rest of the crap left by rodents. I found a huge nest of junk that had been there since before I bought the truck.Tear into the front of the engine and see if I damaged what the CPS reads from when I removed the CPS. Any suggestions? Replace timing chain front seal ect while I am in there. Could these problems be caused by a loose timing chain?New PMD or good used. Can't afford either yet. Anyone have a known good used they would sell cheap?Replace IP with a new or rebuilt. I hope this isn't it since it will be a while before I can afford it.All suggestions and help is greatly appreciated.

PLEASE HELP!

i am new to the 6.5l and studying what i can, i am poking around SS diesel supply website. came across this. read thru. i currently have a Dodge w/12v cummins (I count the days till i can get back into a GM, but the 12v Cummins is SO darn reliable), it has what's called an "overflow valve", it is a check valve that holds x psi at the IP - it is on the return to the fuel tank. even though you have pressure going into the IP from the LP, if the check valve at the back end isn't holding it, there won't be enough fuel - INSIDE the IP. also, MPG's will suffer. good luck, this may be a possiblity. just a matter of going thru the list of possiblities.

94+ Fuel Pressure Regulator Valve
Fuel pressure regulator valve for all 94+ 6.5TD trucks using the DS4 electronic injection pump.
http://www.ssdieselsupply.com/images/pixel_black.gifhttp://www.ssdieselsupply.com/images/products/thumb/190--20061204145754.jpg
Go To Larger Photo (http://www.ssdieselsupply.com/product_190_94_Fuel_Pressure_Regulator_Valve.html# anchor_pimage) Model: ssd-1488 $49.99

Fuel pressure regulator valve for all 94+ trucks using the DS4 electronic injection pump. Includes all C/K trucks, Suburbans, Tahoe's Yukon's, Van's, School buses and Hummer H1's.
On the DS4 pump the regulator is built inside the return line fitting. It maintains the required 3-5 psi fuel pressure. It also acts as a check valve to prevent the reverse flow of fuel to the tank while the engine if off.
If your fuel pressure is low, it may be a bad regulator valve. Symptoms of low pressure are stalling, hard starting, and a hesitation or stumble on acceleration.
To check your pressure use our test gauge ssd-242 or permanently mount our ssd-215 gauge kit.
Installs in minutes with basic hand tools.

Couldn't I hook up a gauge in the return line and make sure it is keeping proper pressure?

I am not sure what to tell you anymore, I think your first target should be trying to get a new PMD. The price has dip by a bit after the release of the DTech PMD, it can be had for under 200. I guess, my suggestion is try to save up some money to get that first since it is KNOWN to be the most problematic parts for 6.5. It is about a 95% chance that PMD which is inside the engine compartment bad when you have stalling problem.

I never heard of a standard pressure for the return. If you hook up a gauge to the return you can become familiar with the return pressure over time. Then if something changed you would notice.

Tried clear line from filter to IP. No apparent air leak.
I did find a small hole in the tube going up through the center of the filter. I am afraid this may allow fuel to pass through without being filtered. Replaced all O-rings, and fuel line on the return. All others were replaced previously. Installed a small inline filter before the fuel enters the IP untill I can find a replacment filter housing.

Pulled the intake to check the wiring harness. Found one damaged wire on the temp sensor. It had a couple of threads of copper still holding it. Didn't think it had to do with my problem but repaired. I had checked resistance from most sensors, ect to the PCM previously.

Pulled the top off of the IP while I was in there. Fuel looked crystal clear in the IP. I vacuumed all of the fuel out of the IP and did the optic bump while I was there.

Cleaned out the intake while it was apart. Trimmed some of the aluminum out of the upper intake to improve airflow. There was some carbon build up in the intake from the exhaust feeding through the egr valve.

Removed the pump mounted driver and compared it to the one I had on the intake from SS diesel. It had a #5 resistor, SS diesels setup came with a # 9 resistor.

Moved the PMD to the nostril of the bumber. I made the wiring harness.

Unplugged the computer and let it sit a while. Mutava tried a different PCM in a truck that he had tried to change the CPS in and it didn't work. Plugged the old one back in and she cranked.

Put it all back together again and after burping the IP cranked and died. Same as before. Unplugged the OS and cranked. She ran fine. Plugged the OS back in and unplugged the CPS. She ran fine again...in limp mode still. Tried both of the PMD's and still same results.

Plan of action: Now that it is back together.

Test the CPS with and oscilliscope. I hope this will let me know it is getting a good signal and I didn't mess up the gear the CPS reads from when pulling out the old CPS.

Check both PMD's on a running truck. If they both are bad I will go ahead and purchase a new PMD.

After that, IP? :eek:

F

I have to say that Heavy Chevy 95 is too quick to blame the fuel. Biodiesel has been tried tested and trued. It is way better than Petroleum Diesel. The only known issue with Biodiesel and fuel systems is rubber fuel lines and you will know that quickly. If you own a newer vehicle (post 96) then you are most likely ok. I can say that I have never heard of a post 96 Diesel truck having fuel line issues related to Biodiesel.

So in short I am debunking the theory that the Biodiesel caused your issues. That is all I have to offer, but I am relatively certain that you already knew that. I believe that I read you had changed your fuel lines, if so I hope you use Viton. Todays trucks really need Biodiesel to replace the lost lubricity of ULSD. Many studies have shown that as little as 2% Biodiesel added to Petroleum show marked improvement over the performance of the older high sulfur petro diesel.

Upon cold start, does the radiator hose get hard quickly? Yes

I think you have more than one problem.

I don't have the time to read every post, but I saw the CPS code. I'd replace the CPS, PMD, then injector pump. In that order. After doing the pump, I'd pull heads and either replace the head gasket or cracked head that is causing the hard cold hose.