Picked up a non-running 94 K1500 6.5 TD as payment for a bad debt, it's about to put me deeper into the hole. Vitals are 162,000 miles and appears to be well kept. It's an auto and 4x4 std cab long bed. Starting off, PO stated it would not start suddenly, suspected lift pump as it gave no other signs or symptoms other than not starting. Brought it home and with this forums content checked the lift pump, tested out ok, pumping fine. Noticed the motor turned very slowly during those tests, so I checked the batts - weak. Fully charged overnight, try again and still turning very slowly. Grabbed both known good batts from my 6.2 burb and tried them out, only about 4 months old - still very slow. Proceeded to replace the starter, and after I conquered the front bracket on that thing I was feeling pretty good about myself and the world. Changed FF and air filter for good measure, placed my clear tubing over the nozzle on the filter into a jar preparing to bleed the air out. Sat in truck, turned the key, absolutely nothing. No clicks, dings, lights, absolutely nothing. Mood soured... Checked batt connections and grounds under the hood, all good. 12.7V on each batt. All connections cleaned, still nothing. Would check the starter relay next, not sure where it is on this truck though, it's my first of this body style. You guys got any suggestions on where to go from here, and does anyone have a wiring diagram for this truck? I'm sure the starter is hooked up right, only two wires on it. I'm feeling lost at the moment and welcome any ideas or suggestions anyone has. Thanks in advance!

 

Be sure the activation wire is on the S terminal and not the R terminal on the starter and check for power there when a helper turns the key to crank.
Might just be a junk starter-china tremclad rebuilds abound and the replacement starter solenoids are really bad anymore.

Next play with your gear selector,the neutral safety switch might be causing grief if out of adjustment.
Diagram for standard trans,your neutral safety will be on the trans shift location:
http://www.justanswer.com/chevy/2387...00-pickup.html

 

Hey thanks racer55, I will check the starter wire position tomorrow, and didn't think about that neutral safety switch. Thank you for the link as well. I found wiring diagrams for the truck on autozone.com. I got this starter as a rebuild from Advance, not sure theirs are any good or not but hoping the lifetime warranty doesn't mean replace it for a life time! It just really blows my mind how the truck went from electrically normal seeming sans the starter, the replace it and EVERYTHING is gone.

Thanks for your feedback, and sorry for the newb questions. I've only had Ford I-6's and the old 6.2 suburban, both had quite a few less electrical gizmo's than this one.

Thanks again!

 

that little wire powers everything

 

I really appreciate the help with that issue gents, it seems to have been the neutral safety switch. The gear selector on this truck was very loose. Gave it some attention, cleaned all connections under there, doctored up one wire and we are back to power everywhere and the truck turning over as it should.

That said, I'm on to step 2 which prompted it all - a no start issue. So far, here is the progression I have taken:

1. Fuel in the tank - OK

2. Glow plugs - OK. All showing 0.8~1.0 Ohm on mutlimeter, continuity back to controller, 12V @ controller and 12V on the other terminal when turning the key w/ glow plug light on dash on. Have not taken them out to check heat however.

3. Fuel getting to IP - OK. Got fuel from the round black valve thing on top of the fuel filter, also from the hose by the T-handle.

4. Fuel return - OK. Pulled hose from the front side of IP, placed short length of hose on fitting. Truck still would not start, and I got fuel from that port.

5. Service engine soon light functioning? - OK. Yes, it lights on the dash when I turn the key.

6. IP Optical sensor check - OK. Disconnected as I read this will put the truck in limp mode and might run (as long as CPS isn't bad). Truck did not start.

7. Engine shutoff solenoid - OK I think. Got voltage across the two wires at that connector.

8. Verify engine getting fuel - OK I think, little unsure here. I loosened the injector nuts about a turn and turned the engine over. It was wet beneath them when I looked again. Not a lot of help around last night so I don't know if it was a stream or a dribble?? Was bone dry before, and wet after I turned the engine over a few times. I may need to spend a little more time on this one, but I think it's OK.

9. PMD - inspect connector for damage - OK. It is a second PMD (this one is gray where the original was black if that matters). It is connector to an extension harness and is mounted on the drivers side of the intake manifold. connectors are in good shape, all wires have continuity.

10. PMD - check power and ground - OK. Got 12V on pink wire coming to the PMD grounding to intake manifold, and 12V on black wire in position C on PMD when connector red test lead to pos battery terminal. Got 12V on both PMD black wires for that matter.

11. PMD - Test voltage on green PMD connector wire - FAIL. Had ground lead on intake manifold and red lead on terminal behind green wire in PMD harness. While cranking I was looking for ~1.2V, got nothing. Cleaned connector and wire-brushed area of the intake manifold, tried again and still no voltage while cranking.

Does this mean I've got a bad ECM? I'm very lost about the next step here. I've seen a few posts around about checking for that voltage, but not a lot about what to do or what the problem might be if the voltage isn't there. Hopefully I'm not the first one to fail this test?!?

I had the top of the intake manifold off to get at these IP harnesses and wires, and the only other thing I can mention is that while I was trying to crank the engine, I was getting a fair amount of whitish vapor or smoke back up out of the intake. Could have well been from that EGR port, I was looking between the bottom of the hood and the dash trying to see what I could.

Does anyone have any suggestions about a good next step? I welcome any additional feedback and thank you in advance for any help or guidance you can offer!

 

I’m having the same or similar issue I have 1.2 volts on the green wire to the pmd for the first revolution of the engine and then it goes blank after. No voltage if you continue cranking. I also only have a mist of fuel coming out of ip at first turn over then nothing after continuing to crank. I’m assuming th voltage on the green wire needs to be constant please help

 

OK first things first . . .

1. If the cranking speed is not over 200 rpm, the DS4 IP will not inject at all. You said cranking speed was slow. This will include a bad crank sensor too which is how cranking speed is detected.
2. BUT FIRST . . . . you may only think your fuel pressure is fine - and I said fuel PRESSURE. THOSE OEM LIFT PUMPS WILL SEND FUEL AND THEY WILL MAKE LOW OR NO PRESSURE. Ideally those DS4 IP's run best with over 10 PSI at the Inlet. 10 to 14 psi is running spec. 5 psi is absolute minimum at all times at the IP inlet. Just because you think you see fuel moving means nothing. I run - and my DS4 never acted right until I put-14 to 16 psi regulated at the inlet. Get a lift pump that can put a minimum of 10 to 14 psi at the inlet. Watch out for someone who previously owned thee truck who may have put a LARGER than stock fuel line on the IP inlet. This drops fuel pressure - and it is PRESSURE and not volume that makes the IP work. DB2 engines like you describe are NOTHING like the DS4 - they only look similar.
3. You talk about colored wires on the PMD inlet at your items lines 8 to 11 - the colors mean nothing - because Chinese harness manufacturers mix all the colors up - but I can tell you the third one from the end looking one or both ways you can identify as hot - because it will have a bluish tint to the metal - as that is the one that is HOT in RUN and START - if it is not tight - you will get a no inject and no start condition also - you need to make sure that wire has a tight connection to the PMD pins.
4. Unfortunately on the 94 the OIL Pressure switch has a a lift pump function also and if there is a bad one or no oil pressure you will get no lift pump power while cranking and also a no start condition.
5. Unfortunately there is also a bug in the ECM firmware that can cause a no start condition unless you break power to the ECM and plug it back in by removing and reattaching the battery cables.
6. For slow cranking if not the battery or starter - make sure the grounds of the cables - actually both - are really clean on both ends so they can carry as many amps as the batteries have to offer. Mine had slow cranking and was hard to start also because of the cranking speed and I used to - and still do - carry a small portable generator and 200 amp hot start battery charger for if I run the battery down on cranking. Have not needed it for a few years though I keep it in the vehicle.
7. Glow plugs all working - are a must on a cold GM 6.5 - and ether is NOT a good idea. There is a glow plug relay that could be bad
8. Finally a working Fuel Calibration resistor is needed - they do get hot in that confined space in the PMD connector and the only way to test them is with a VOM to the connections of the holes that contact each pin. Better yet - just get new ones because those little holes have scrapper contacts that loose termper and do not make connections on the pin tight and do not work anyway
9. And lastly if you never had the PMD running the engine - do not try to test it or use it - the power resistors seen by flipping it over may work intermittently if at all. You can get a whole relocation kit with new PMD for $60 on ebay as item 282862635738 shipped out of California. Yes it has a Chinese / Dorman PMD - but now a days they all are. I mounted mine on the front rail under the hood are the top next to the radiator using a hinge so I could flip it up quickly to change it and so it would be in the airflow that comes under the crack where the hood meets top plate. When the engine is running - you should be able to hold it with your hands and it be ONLY warm - and if it is HOT - something is wrong - like weak fuel pressure - or one of the power transistors is blown on the PMD.

BUT first things first - get a truly working lift pump - and NOT a new OEM style lift pump - I have seen dozens of them that NEVER make pressure for even a few hours. I use a Sure Cure Lift Pump and it came with three lift pumps - two working axial Dodge style ones, and a canister wet style for emergency use that the brackets are actually used from and a back flow presenter and adjustable regulator which is set at 19 to 20 at the pump and ends up at 16 to 14 depending the age of the fuel filter at the IP inlet. It is really quiet. Mine holds pressure in the line when the engine is shut off and starts instantly usually even if overnight. I do have Bosch glow pugs also which are good at long life. If your batteries do not have enough CCA to heat the glows plugs and then crank the engine fast when cold - it won't start - or start easily. As a side note, the pressure was also to cool the IP and thee PMD mounted on the side by having fuel constantly recirculating to the tank out the check valve at the top. This is how the whole PMD relocation industry got started - no fuel pressure to keep the IP full and circulating cool fuel and thus the side of the IP got hot - engine bay hot - and this shortened the PMD life.

How do I know all this ??? - I worked with a Diesel Specialist shop which specialized in GM 6.2 and 6.5 engines - and I can tell you when the crank sensor went out on the Hartridge flow and pressure test bench used for testing IP's to spec after rebuilding - I told the owner it was the crank sensor on the stand - and he said he just replaced it so it was not that. I troubleshot the Stanadyne companion test module for the unit which had no 12 volt signal going to the PMD as it has an ECM and setup like a vehicle - and after three days I found it to be three things. Oil soaked wiring on all the connectors that plugs into the DS4 had shorted the ECM and blew the 12 volt regulator on the ECM board and when that was fixed - it could be nothing left but the crank sensor - which was also blown by the short due the wet oil in the connections and lines. So we were both right - the crank sensor was not sending a 200 rpm signal and so the IP would not inject because it was shorted blown and now bad, To replace it again and the units began injecting.

Since you cannot SEE the Injectors injecting - start with the obvious and worst flaw of the GM 6.5 engine - the OEM defective design lift pump and with a regulator you can SEE the pressure read out on the gauge of the regulator.

The PMD has two functions - it sends a signal to the IP to inject - and it controls by the accelerator pedal and to make the engine idle as a drive by wire throttle. That is how the PMD's blow - trying to hold open a Fuel Solenoid on the rear of the IP when there is no fuel pressure to inject and open the injectors. So if you have pressure to the inlet of the IP of a minimum of 10 to 14 psi, it should start or at least try to stumble start - as the pressure in the IP lines also controls idle and it will push the fuel solenoid plate open enough to idle the engine

What you got was someone else's headache they did not know how to solve - and it is easily solvable like I outlined above. Of course there is always a chance there are mechanical issues beyond the scope of just a sick DS4 IP system but if you do not have those this above will put you on the path to get it running and keep it running without problems.