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1994 c3500 6.5 liter diesel

Welcome Woolydogg.

Lots of knowledge & helpful folks here.
Please fill out the signature line with the truck and any modifications made, Marty’s is a great example. It really helps as people read through to keep track of details.
 
good morning mr marty im still struggling with my 6.5. i was wondering if while i have a glow plug out if im looking at the back of a valve or the piston. ive got a new injector pump installed and trying to make sure i have the timing right as it will run but wont accelerate. can you help me out with some knowledge?
 
Welcome @woolydogg Were all here to help!
Give us a little more detail on your truck. what all the issues are and what you and others have done to try and fix it. any upgrades or modifications that have been done as well. best thing is to fill out all the rig details in you account signature for us all to read and see each time you make a post. also posting pictures helps us a lot so we can all see what your looking at too! besides we all love a little truck porn LOL

for setting the IP timing, we need to know if you have the electronic DS4 or the mechanical DB2 pump. easy way to tell is if you have actual throttle cables running to the IP from the cab or just wires. biggest downfall for the DS4 is you will need a scanner to set the timing, and just a heads up, the snap-on scanner won't do it properly.
 
Ok the issues I was having were black smoke and not revingup past 2500rpms so I changed out my ecm and pcm got alot of different codes changed out throttle positioning sensor nothing changed so I got rebuilt Bosch injectors had them torque and the spray set. Got a newly rebuilt injector pump and it along with the injectors have been installed. Still runs but won't excellerate I can get up to 1200 rpm.s now and no more. I installed a new crankshaft positioning sensor this morning I haven't started it yet as I have the timing cover off to check my timing marks. One question I have is can you see the top of cylinder 1 if you take out the injector and run it up to t.d.c ?
 
unfortunately no you can't see the top of the piston. line up the timing marks on the sprockets if you have the cover off.

what codes did you have prior to replacing the PCM, and what codes do you have currently? I assume you swapped the prom chip from the old to the new PCM?
 
I can't find any pics online to give a visual on the timing chain and IP gears, but there are some decent youtube videos on the timing chain replacement that shows good detail.
 
O.k I've got the timing cover off and the timing marks on the cam sprocket and injector pump sprocket lined up along with the t.d.c on my harmonic balancer. I did not change out the prom chip from the old p.c.m. the last code i got was for the injector pump or injector pump harness or crankshaft positioning sensor i change out the crankshaft positioning sensor this morning.havent did anymore today waiting on radiator hoses. All three things were probable from the code reference.
 
do you still have your old PCM and prom chip? they make a difference and tells the PCM what engine/trans you have along with type of programming. if you have them. can you tell me what the 4 letter code is for the old and the new? I assume you got the new one from a donnor truck. new ones from the auto parts don't come with the prom chips.
 
Here is something I found on another forum about DTC code 18. it might help. I copied it word for word including the links.

DTC 18 troubleshooting starts on page 15 of this:Click Here

How to test your lift pump and Oil Pressure Switch (OPS): Click Here

If the engine stops after 30 seconds or so, Click Here to see how to jump the lift pump relay connector to power the lift pump. If you get steady fuel flow from the T valve, the lift pump is working and the OPS is bad. Replace the OPS with an AC Delco D1808A OPS. Dont waste money on any other brand as other brands will fail quickly.

On a 1994 it is pretty much essential to do this mod: OPS Relay Mod. Get NAPA - AR143 Relay, Relay Connector: NAPA - ECH EC23 or Relay Connector (with mounting bracket): NAPA - ECH EC38. Instead of tapping the orange wire you can get 12v from the Power Block on the passenger side of the firewall.

How to see if you have air in the fuel system: Click Here
 
from what it sound like, you have air in the fuel system which is a common problem and can be hair pulling to fix. also need to make sure your lift pump is working and providing correct pressure. when they fail it can pull the fuel system into a vacuum and create air leaks from anywhere in the lines. not having ample fuel pressure will destroy the IP as well.
 
the lift pump is powered through the ops (oil pressure sensor) a common failure point and why so many of us have done the relay mod. some folks also add a signal wire from the GP (glow plug) controller to energize the added relay so the system will prime while the WTS (wait to start) light is on prior to cranking.
 
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