6.5 reassembled, won't start. Please help! Trying to meet a deadline.

[campfire]

Update time!!
I'm home from PA. I have a new starter on after the old one died. She cranks all day and builds 40lbs of oil pressure. Still have fuel to the t handle bleeder, but no start. Not sure where to go from here.

Crack open a few injector lines (loosen the injector end of the line). Then crank and post up what happens. If you immediately get fuel out of the lines, injection is not likely your problem. If you are airlocked, you should see fuel appear at the end of the lines after a bit of cranking (anything from 5 seconds to 2 minutes for completely dry lines). If so, following the same procedure for the other injectors should get them all bled properly. If you crank it endlessly and it never does get fuel, and you have fuel going into the IP, then (and only then) would I look inside the IP. Verify flow into the IP by removing the overflow line and checking for fuel flowing out during cranking. Crucially, check for air bubbles coming out with the fuel. Air bubbles are your biggest concern at this point.

 

[campfire]

These engines require fuel, air, and heat.

Air is plentiful, as long as you don't have catastrophic mechanical damage (or that timing set could be off by a few teeth?).

The 'heat' part is a good bit simpler than a gasser (no worries about spark timing or advance curves). A glow plug is just a basic heating element. Zero ignition timing issues here, it just needs to dump heat into the prechamber inside the head.

Fuel is mostly a matter of getting the air bled out so the pump will move it properly (hence the post above). Only after you eliminate that possibility would it make sense to look inside the IP.

There's not a lot that can go wrong. Work your way through the checklist, and we'll get this figured out.

 

[campfire]

Did you change the timing gears on the IP? If so, did you remove the IP during that process? Or did it stay fixed to its reference mark?

You'd have to be pretty far off the mark for the engine to not run. But I figured I'd ask, just in case.

 

[2INSANE]

Just because your glow plug light turns on and voltage drops, it does not mean your glow plugs are working… All it takes is 1 bad plug and you have problems.

Step 1.

Check the voltage going to each glow plug using a multimeter. Should read 12+volts if your batteries are charged or 10.5 volts if you have the self regulating G60 plugs.

Step 2.

Remove all your glow plugs and check the ohms on each one with a multimeter that has a ohm buzzer. If the ohms read something stupid high or nothing at all as seen in pic 1 and you don’t get a buzz from the multimeter, you have a bad glow plug. If your Ohms are constant and show about 1.2 or .002 to 1.5 or .005 and buzzer goes off on multimeter, your plug is good as seen in pic 2.

After verifying your plugs are getting the proper voltage and are working, go next step.

Step 3.

Install a clear fuel hose going from the injection pump return nipple and the other end on the hard line return nipple (Pic 3). Verify fuel is going through and there is no air bubbles. This also verifies that the injection pump internal check valve/filter built into the IP return line nipple is not clogged. (Pic 4,5,6 pending model number)

After verifying you are getting fuel from the injection pump and there is no air in the line, go to the next step.

Step 4.

Since you have your glow plugs out, crank the motor over until fuel starts coming out of the glow plug holes. This is the best way to prime your fuel system after changing injectors/injection pump/etc. If fuel does not come out of any holes then most likely your injection pump is toast, optical sensor, ip not getting the proper voltage, pmd or your lift pump is toast or your fuel filter is clogged. Could be a hand full of issues. If fuel comes out of most of the glow plug holes but not 1 or 2, then you will know what injector/s to replace.

After each step is complete, please update us and if you still have not found your problem we will go on to the next steps which are more advanced.

 

[The_Tomato]

Just because your glow plug light turns on and voltage drops, it does not mean your glow plugs are working… All it takes is 1 bad plug and you have problems.

Step 1.

Check the voltage going to each glow plug using a multimeter. Should read 12+volts if your batteries are charged or 10.5 volts if you have the self regulating G60 plugs.

Step 2.

Remove all your glow plugs and check the ohms on each one with a multimeter that has a ohm buzzer. If the ohms read something stupid high or nothing at all as seen in pic 1 and you don’t get a buzz from the multimeter, you have a bad glow plug. If your Ohms are constant and show about 1.2 or .002 to 1.5 or .005 and buzzer goes off on multimeter, your plug is good as seen in pic 2.

After verifying your plugs are getting the proper voltage and are working, go next step.

Step 3.

Install a clear fuel hose going from the injection pump return nipple and the other end on the hard line return nipple (Pic 3). Verify fuel is going through and there is no air bubbles. This also verifies that the injection pump internal check valve/filter built into the IP return line nipple is not clogged. (Pic 4,5,6 pending model number)

After verifying you are getting fuel from the injection pump and there is no air in the line, go to the next step.

Step 4.

Since you have your glow plugs out, crank the motor over until fuel starts coming out of the glow plug holes. This is the best way to prime your fuel system after changing injectors/injection pump/etc. If fuel does not come out of any holes then most likely your injection pump is toast, optical sensor, ip not getting the proper voltage, pmd or your lift pump is toast or your fuel filter is clogged. Could be a hand full of issues. If fuel comes out of most of the glow plug holes but not 1 or 2, then you will know what injector/s to replace.

After each step is complete, please update us and if you still have not found your problem we will go on to the next steps which are more advanced.

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Wow. What a write-up, thank you. I'll walk through these steps and get back to yall asap.

 

[Big Ray]

Just because your glow plug light turns on and voltage drops, it does not mean your glow plugs are working… All it takes is 1 bad plug and you have problems.

Step 1.

Check the voltage going to each glow plug using a multimeter. Should read 12+volts if your batteries are charged or 10.5 volts if you have the self regulating G60 plugs.

Step 2.

Remove all your glow plugs and check the ohms on each one with a multimeter that has a ohm buzzer. If the ohms read something stupid high or nothing at all as seen in pic 1 and you don’t get a buzz from the multimeter, you have a bad glow plug. If your Ohms are constant and show about 1.2 or .002 to 1.5 or .005 and buzzer goes off on multimeter, your plug is good as seen in pic 2.

After verifying your plugs are getting the proper voltage and are working, go next step.

Step 3.

Install a clear fuel hose going from the injection pump return nipple and the other end on the hard line return nipple (Pic 3). Verify fuel is going through and there is no air bubbles. This also verifies that the injection pump internal check valve/filter built into the IP return line nipple is not clogged. (Pic 4,5,6 pending model number)

After verifying you are getting fuel from the injection pump and there is no air in the line, go to the next step.

Step 4.

Since you have your glow plugs out, crank the motor over until fuel starts coming out of the glow plug holes. This is the best way to prime your fuel system after changing injectors/injection pump/etc. If fuel does not come out of any holes then most likely your injection pump is toast, optical sensor, ip not getting the proper voltage, pmd or your lift pump is toast or your fuel filter is clogged. Could be a hand full of issues. If fuel comes out of most of the glow plug holes but not 1 or 2, then you will know what injector/s to replace.

After each step is complete, please update us and if you still have not found your problem we will go on to the next steps which are more advanced.

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This needs to be a sticky!

 

[Truckman4life]

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[The_Tomato]

I'm not an expert on DS4 error codes. But I did some preliminary searching for you.

From https://www.troublecodes.net/gm/94-95_65/

​

18​	Pump Cam Reference Pulse Error

​

84 ​	Accelerator Pedal Position (APP) Circuit Fault

The PCM is comparing the input from both the crank position sensor and the optical sensor inside the IP. This code doesn't tell us which input is wrong, just that the two don't agree. Is it possible that the pump isn't meshed properly with the timing gears? Or that the crank position sensor isn't installed/functioning properly?

Yes!! Very possible. I didn't scribe a mark into the cover for the timing gears when I removed so I have no way of knowing my IP timing. Do you know how to check it?

 

[The_Tomato]

Ok. Glow Plugs are out and verified within spec, except 2. I have 2 AC Delco replacements. I haven't put a clear line on the return, but I pulled the hose and had a buddy crank. Fuel is coming out. I'm going to verify that the harness works, but first things first I've done quite a bit of cranking and no fuel has come out of the glow plug holes. I didn't scribe a timing mark for the IP, and last I checked I'm getting error codes 18 and 84. According to the shop manual, 18 indicates 8 missing cam pulses in the IP low-res circuit for every pulse of the crank sensor. 84 is an intermittent APP (accelerator pedal position) circuit fault that won't illuminate the SES light.

I've verified fuel up to the IP, now what? Keep on cranking?

 

[2INSANE]

Ok. Glow Plugs are out and verified within spec, except 2. I have 2 AC Delco replacements. I haven't put a clear line on the return, but I pulled the hose and had a buddy crank. Fuel is coming out. I'm going to verify that the harness works, but first things first I've done quite a bit of cranking and no fuel has come out of the glow plug holes. I didn't scribe a timing mark for the IP, and last I checked I'm getting error codes 18 and 84. According to the shop manual, 18 indicates 8 missing cam pulses in the IP low-res circuit for every pulse of the crank sensor. 84 is an intermittent APP (accelerator pedal position) circuit fault that won't illuminate the SES light.

I've verified fuel up to the IP, now what? Keep on cranking?

You need that clear hose from IP to return line to verify the fuel is coming out and no air is in the fuel lines.

When the fuel system is completely empty, it may take a lot of cranking to get the fuel to the injectors.

Chisel a mark on the Timing cover and injection pump and then turn the injection pump driver side to advance the timing. See if that helps.

Also can add diesel fuel in the intake to see if it will start.

I added a few pictures of the timing marks in comparison to where piston 1 and the valves should be at TDC. And where the injection pump timing gear dots should be when you install it.

 

[The_Tomato]

Howdy everyone.

This truck frustrated me, and I hadn't touched it for a minute. I'm back now, better funded, better equipped, and with less time pressure. I really need help though, as it's pretty easy to get discouraged with this project. I don't really understand what's going on, but I can outline what I've done so far. Also, if someone would be willing to speak with me via phone or video call, that would really help. With no further ado:

I've seemingly narrowed the issue down to an IP/PCM issue. My lift pump functions, my OPS has been replaced as it was bad, I have fuel from the return line and the bleeder valve, and I've removed all 8 glow plugs to get rid of any cranking resistance from compression. I cranked for a while to see if the system would bleed and push fuel to the injectors, but nothing happened. I then pulled the intake and the hardlines AT the injector- still nothing, not even a drop or dribble, from the IP. I got to wondering why, as this truck ran just fine before I started all this. I realized I had replaced the timing chain and the CPS. Maybe the PCM doesn't have the info it needs to fire the IP?

Side note- I went ahead and got a PMD relocator kit and have it installed, so a faulty PCM isn't to blame here. The cutoff solenoid on the IP also clicks as though it functions correctly, so I don't think it's that but I'm happy to be proven wrong. I now have an OBD1 to USD cable and GMTD scan tech, but I need some direction here.

 

[The_Tomato]

I also verified that all of my glow plugs are within spec using a multimeter, as was previously suggested.

 

[2INSANE]

You just narrowed down your problem. It is your injection pump or electrical issue going into it. I don’t have the time to search on Google for you on how to test your wiring., but I know there are some retired gurus on thedieselpage.com that would be thrilled to share their coveted manual diagnostics papers!

You verified fuel is going threw the injection pump return line right, so it’s getting fuel but the IP is not pumping it into the injectors.

If you want to go above and beyond, you could also add some fuel pressure gauges before and after your fuel filter system as seen in my photo. After sitting overnight, my system still has pressure which verifies I have no leaks, my lift pump works and my fuel filter does not need to be replaced as both gauges are at 9 psi.

Edit: In addition, did you try turning your injection pump toward the driver side to advance it? It’s 3 15mm bolts which requires a pivot ratchet wrench to turn easily and a bar on the injection pump line nuts to twist the pump driver side to advance.

 

[2INSANE]

Got an update for us?

 

[396 TransAm]

Subscribed

 

[bigred81]

Subscribed

My 95 k1500 6.5 was doing the same thing did a lot of what you checked but the last thing I did was check my crank position sensor it was shorted on the 5 volt reference. Replaced the crank position sensor with an nos sensor I found online still running good 5 years later.