1. Does the engine crank, or 'turn over'? Yes
1a. Does the engine start and run? No
1a1. If the engine does not start - Crack injector line (http://www.dieselplace.com/forum/showthread.php?p=2188140#post2188140): do you have fuel? Very little
1b. Do you have a Wait To Start Light & the amount of time (seconds) lit. Goes on and of w/ glow plugs
1c. Ambient Condition (temperature outside indicate F or C) _____60 °
1d. Engine Cranking speed (if you have an accurate tachometer). 150rpm
1e. Are you experiencing stalling? Not Starting
1f. If Stalling, describe (upon startup only, down the road, hit a bump etc)
1g. If Stalling, do you notice loss of dash or instruments?
-note if experiencing stalling,you must indicate PMD location in #24.
1.1 Lift pump test (http://dieselplace.com/forum/showthread.php?t=39350)- describe results Flows great at t-valve and filter
2. Service Engine Light while running?- on
2a. Service Engine light does glow during start/cranking/bulb check: Yes
3. Model year 98, motor is dif year, not sure maybe 95
3a. Odometer reading (indicate if in miles or km) 160000
3b. Miles on major engine components if been replaced (example Injection pump) heads 4000
3c. Indicate the model number on the Injection pump (starts DS4 or DB2......)
4. Have you scanned for engine codes? (varies by pre/post 96) yes
5. List exact results on engine codes: p0251a
6. Air Filter condition (visual check) fine
7. Fuel filter condition (freshly changed/condition unknown/mileage since changed) brand new
8. Condition of Battery terminal connections (removed, cleaned and tightened) good
8a. Known condition and age of the batteries. couple hours
8b. Are batteries of differing age or are they a matched set? match set Condition of Major Grounds (http://www.dieselplace.com/forum/showthread.php?t=157085). (same drill as batt - removed, cleaned, retightened) fine except ground strap pass side
9. Upon cold start, does the radiator hose get hard quickly? na
10. Upon cold start, do you have excessive white smoke? na
11. Do you have excessive cranking time before the engine starts? no start
12. Have you used the block heater, and does this effect engine starting?(only try for starting problems) no not sure if it works
13. During hard acceleration, do you have excessive black smoke?
14. Do you have any unusual exhaust smoke issues? no
15. Turbo check out (http://dieselplace.com/forum/showthread.php?t=39368)- pass/fail
16. Do you have an EGR on the engine? (An F or an S engine code 8th VIN digit) ??
17. Indicate if you know if it’s a 1500, 2500, 2500HD, 3500, 3500HD. 3500 hd
18. Indicate fuel that you are using: Bio-diesel, #2 Diesel, #1Diesel, SVO/WVO, other. diesel #2
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. yes lucas and recently switched to 2 cycle
20. Please indicate geographic region you are in: (example: Texas or Canada) Maryland
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? yes
24. Location of PMD/FSD (http://www.dieselplace.com/forum/showthread.php?t=39436)? On the pump/remoted over intake/remoted out of engine bay (please specify placement specifically) intake, i know i will relocate to bumper
24a. If remote mounted, describe wiring harness (homemade or purchased from a vendor?) purchased ssdieselsupply
24b. Indicate the location and condition of the FSD/IP grounding wire. good
25. Are ALL glow plugs in proper working order as per this thread (http://www.dieselplace.com/forum/showthread.php?t=39182)? not kicking a code

any ideas???

no start at all? not even a sputter or white smoke while cranking?

your intake mounted PMD could've quit on you. how old is it? intake mounted get hotter than the pump mounted i've heard. the pump mounted ones stay nice and cool while the engine is running. its when the engine is shut off and fuel stops flowing is when the heat soak happens. the intake mounted one would probably be hot all the time as once the heatsink gets too hot it can't get rid of that heat if the air around it is 150 plus degrees. also Ohm out your glow plugs. i'm not sure what the reading should be for a good plug. just because your not getting a code doesn't mean they are all good. the glowplugs just have a single HOt wire running to them so theres nothing to throw a code with i would think.

wont start at all,pmd is 6 months old. b4 i replaced batteries i had a code for glowplug relay. i will check glow plugs tom 2 make sure

need a relay? *holds one up*:D its a take off from my truck. its good still probably only 6 months to a year old. if it'll save you money i'll let you try this one out to see if you've got a bad relay. PM me if interested.

After reading through your diagnostic checklist I noticed your p0251 code. I had the same code when my IP went bad. It may or may not be bad. It could be your PMD since it is mounted on the intake and it gets hotter there then when mounted on the pump, however when the pmd goes it usually doesn't cause a code. That code could have been there for a while and was never cleared.

Here is what I would do. Unplug the Optical sensor plug on top of the IP and crank her over. This is starting it in dumb mode and the trucks computer will run the pump. It will cause a code but don't worry about that. If it starts it will crank longer before starting. If it starts how does it idle, how does it drive? rough or smooth?

try this and get back to us w/ the results.

ok, disconnected OS, wont start, switched out PMD(went to the back up one i put on pump during head job) wouldn't start. Checked all glow plugs w/test light they r fine. Im stumped

hmmmm.....:confuzeld. did you try cracking an injector line to see if you've got fuel? if you don't have fuel then you can say "Well theres your problem". other than that i'm stumped at the moment.

very little

went over your checklist again. large vacuum in the tank is bad. try cranking with the fuel cap off. another thing i would try(if you haven't done this already) is open the t-valve and purge the pump. the little red wire with the black connector behind the under-hood fuse box. give it 12 volts and you should hear the lift pump running and see fuel coming from the t-valve.(when i do this the fuel seems to come from the front of the motor i think the hose was rerouted on my truck though). if your LP is working and you know that at lesat one of your PMDs is good and you've checked all your fuses and ground wires(R&R for the grounds) and theres no air in the fuel system(open the bleeder on the top of the fuel filter and do the LP purge shown above)then it maybe your injection pump? that would be the only thing left in the fuel system at this point.

- Dave

very little

i don't know if how far you loosen the line makes a difference but for s**ts and giggles. how much did you loosen the line up to test for fuel?

another thing it might be the fuel shutoff solenoid is stuck? that would prevent fuel flow i think(considering its name). again i'm no diesel expert but i'm going by what i read. i don't know of a way to get it "un-stuck" if it is. i would say tap it with something but i don't know if that would break it or not.

took it off, the lp is workin, i sent a pm to cobra 2 c if he could come down and help

if i lived closer i'd like to help out too. i never pass a chance to work on a 6.5 as i can learn more about our trucks. this truck has become a challenge.

i appreciate that

no problem. any chance that both PMDs could've gone bad? i've seen so weird things but that would take the cake. was the pump mounted one good when you stopped using it?

no i replaced the one on the pump when i put new heads on

alright i'm lost. :mad: dammit i hate when that happens. could be a bad IP as someone said the code you've got could be a bad IP. how's the ground wire on your IP for the PMD and shutoff solenoid? clean,dirty,etc?

For info sake run a vin check & see when pump (at 160 k miles assume it was) was changed .

why didn't i think of that?:p:. definitely let us know how things go though.

Many heads or something like that .For sure thats what we,re all about.

cant run vin cuz motor isn't og. bought truck w/o a motor, i got a hell of a deal and i know when i get it runnin right it will pay off

Well it looks like it is the IP. I would do one last thing. Send a PM to GMCTD or turbine and have them look at this thread and see if there is anything that you are missing. Otherwise I would replace the IP.

pm sent thanx guys, let me know if u think of anything else

Okay, with a P0251, as mentioned before by Rodd, you have an issue with the IP. Now, I would not worry about your PMD being bad, only because you have fuel to the injectors during the cranking. If you had no fuel at all, then you'd have an issue. Remember folks, it only takes a few mm3 of fuel per cylinder to keep the engine running at idle. So, we are not looking for cups of fuel to come pouring out of the injector like that of the t-handle with lift pump test. Your computer is searching for what's going on, and has lost touch with reality.

As Rodd said, remove the 6 pin connector on the top of the injection pump. It will take some cranking before it starts, but it should start in limp mode. Give it a try and check back.

The other thing too is that you did not list your time that glow plugs were on for 60° condition. 2 seconds verses 5-7-10 seconds may indicate an issue too.

Ground strap should be in good condtion if you want the ECM happy. Ground between passenger head and firewall that is. It is critical to operation.

Check back and let us know.

As mentioned, P0251 is IP related, and is the Optical Sensor or harness - a bad connection\broken wire gives the same result as a bad sensor - could be pinched or IP harness is bad - '94-'96 had defective IP harnesses and Optic sensors and harnesses, plus the square filter module, which your '98 does not require - if it's there, deep six it, direct connect the OS plugs.

Intake-mounted FSD is not even a good thing, but gets an order of magnitude worse if the black ground wire that is engineered to be on the top of the Inj Pump has been moved or extended or both - has to be not greater than 6" long (oem length) and attached directly to the IP, no matter what you heard from another site or vendor - the blue heatsink does not require grounding, nor does any other color, (quasi)professional or homebrew

Check that stuff out, see what you find

actually i figured out the motor is from a 94, but i will check it

Didn't the 94 come with a different IP that only works with a corosponding ECM??
What is your IP # should be 5521, if different you might have to check out compatibility.

Yes - answer is in his other thread, but I'll post it here for continuity -

Basic question was: DS4831 injection pump - bad or good?

That's only part of the nomenclature - should be DS4-831-XXXX - that indicates Distributor type - Spill solenoid - #of pumping plungers 4 - #cylinders 8 - plunger dia 0.310" - last four are the ever-important pump spec - your '98 could be 5288 - '94-'97 could be 5067 - 5068 is really bad - if you have a 5521, that's the latest and greatest since '00 - shoud be paper label with the number and date code on the rear face on the later pumps.

5068 is really good for higher performance, but very finikey, takes a special chip\flash - also, not even good with an oem '98 PCM

already posted on other thread but the ip # is actually a 5067, not sure if its compatible w/ pcm or not. also, should i still try and connect os to itself. tried to start w/ os disconnected, wouldn't start

I'm staying in the other thread, just for continuity.

i am replacing the ground strap today and would like to check harness w/ ohm meter if someone could tell me how

Not much way you can check the '94 5067 harness - but, it is crimp-only tinned copper wiring - the replacements are crimped\soldered, using silvered high conductor-count teflon-insulated wiring - only about 35bucks at several of local vendors - at one time, Stanadyne would warrant FSD\PMD replacement (1-year) if the included harness was installed with the new module - some vendors would send the module and keep the harness for later sale - I would replace that first, try a start - if not, disconnect the OS harness, try a limp-mode start on the Crank Position Sensor only - this takes quite a while, but will start and run, just with no timing, no rpm, and no power

Then again, you may have a defective DS4-5067 - a black label indicates it is original - if it has black label and a small green tag on the top, it has been rebuilt - if it has a blue label it has been rebuilt - if it has a blue label and a green tag, it has been rebuilt - even at that, in 2008 it's getting mighty long in the tooth, and will be a condiserable source of trouble if not recently serviced - you can pull it and have a good fuel injection shop bench-test it for proper flowrates across the rpm range, idle to WOT

it is a blck label, so it is og, my friend gave me one of his old pumps as a core, im hopin its the newer version. i think ima go down to a stanadyne shop and c how much 2 rebuild. anybody wanna guess???

well the 2 shops i found that will rebiuld it, one is $1180, and the other is $975. unbelieveable.

I sent you a PM.

got it thanx

ok jus for giggles i replaced OPS, didnt help. could it be ign/switch??? or CPS???