1995 6.5 crank/no start

[RGerard]

Truck info in signature.

Truck is cranking strong but getting no start. (no rumble, no attempt at firing, no smoke out tail as I have no combustion/no fire.) Very cold in Colorado the night it started. Of course I worked late that night and tried to leave for home. Ended up leaving it for the night and plugged in the heaters. Towed home next day after trying regular fixes (wiggling wires/basic ohmeter tests, hoping it was an electrical issue i could see in the daylight).

Block heater/inline radiator hose heater both working so everything warm. Glow Plugs lights as normal so assume working but have a new set on me as I planned on replacing them. Fuel flowing in filter, through drain T. The fuel shutoff solenoid is retracting and springing out when key turned to ON but I am getting a code 13 which I believe is Engine ShutOff Solenoid Circuit Fault.
Jumpered lift pump at relay and can hear running and pushing fuel through drain T at good pace.

Fuel filter seems to have some slight air after cranking, but when I crack open injectors on drivers side I am getting no dripping fuel. Removing the line, I see fuel but cranking does not seem to force it out.

I have intake maniford cover off now to get better look at injection pump so some sensors are disconnected and current codes are 13, 14, 35, 36, 41, 62.

Only other time I had similar situation was after IP replacement and the fuel shutoff solenoid was the culprit. I used my old solenoid in place of the 2 new ones that came with the IP and fired right up.

Ideas anyone? I am leaning towards fuel issue but do not want to overlook something someone else may have encountered.

[JohnC]

No smoke, no fuel and Code 13 point to the solenoid, but the other codes (and 13) could also be caused by a power issue. I've seen issues with those ignition switches that are actually temperature dependent.

[RGerard]

hmmm. I remember buying an ignition starter switch (harness) a couple of years ago when I was diagnosing another problem and was going to have steering wheel apart. (I think maybe attempting to fix the turn signal switch/hazard button) but cannot honestly remember if I installed it or returned it. I think I was also chasing a problem that eventually led to coolant temp switch wiring, and was being advised to replace harness due to age of truck to eliminate some random electrical gremlins.

When I tested fuel shutoff solenoid, i did just check for operation, not for actual voltage. I think I will check for actual 12V tomorrow, and look at the ignition starter harness. I dont know exactly what triggers the DTC 13 code (malfunction, insufficient voltage, etc. ie... what exactly is dtc13 telling me about the solenoid other than look at it as possible problem?)

I really hate chasing codes on this truck. There seems to be so much redundancy of the operation of parts that leads you down a rabbithole sometimes.

Since planned on doing glow plugs anyway, prob good as time as any to pull old ones and see if I can bleed some air out. All this cranking can't be good on the starter.


Forgot to mention I also tried swapping PMD this AM with an older one I had. (When I did initial relocation, i had bought new PMD and kept the original as a backup so not sure how good it is but assuming good enough to at least "start" the truck if my current PMD is suspect.)

[JohnC]

I really hate chasing codes on this truck. There seems to be so much redundancy of the operation of parts that leads you down a rabbithole sometimes.

Address the codes in numerical order. (DTC 13 first.) Sorry, my service manuals are long gone. Sold my '95 in 2005.

[RGerard]

Yessir, I generally start with the lowest number first and then progress.

What I meant was that I did not look at DTC codes first before I started to crank and disassemble and try different things. I guess I will clear them, reassemble the different parts and sensors disconnected and then begin again and see which ones reappear.

Am going to research a bit more into the DTC13 solutions as the shutoff solenoid (not the particular one installed currently) was the cause of another no start condition as I stated previously. It was only out of total frustration that I swapped the solenoids and truck started. I never even bothered to find out exactly why the solenoids that came with the IP did not work. At the time I did not care, it was finally running, and I was satisfied.

Thanks for your help so far.

[RGerard]

Ok reassembled and cleared codes.

Currently have dtc 41 (brake switch circuit) and dtc 62(Turbo Boost Sensor Circuit Low).

No start still. Going to start tracing wires and also find my fuel pressure gauge in the garage. I have tried jumpering past Oil Pressure Switch, Fuel Shutoff Solenoid, disconnecting Optic Sensor on Injection Pump. I am also considering Crankshaft Position Sensor. (although I am not getting a DTC19, that seems to be only sensor left I can think of affecting start)

I cant seem to find anything that describes the actual "order" of starting. Like A happens before B, then C.

All my previous no starts through the years have been due to some sort of electrical part or sensor or loose wire but the regular culprits/fixes dont seem to be working this time. the only extended no start (days and days of cranking and searching was that fuel shutoff solenoid). About to see if i can pull some fresh diesel through filter to eliminate bad batch of diesel or contaminate. Something still says electrical though because no performance issue prior to just dying. Just parked it for the day like usual and returned to a no-start.

[arveetek]

Having a confirmed fuel supply to the IP but no fuel at injectors does point to an electrical issue of some sort. I would try to find a known good PMD and give that a shot. I would be suspect of the original PMD you tried.

Casey

[RGerard]

Turned out to be the PMD extension Harness. Truck is starting right up with PMD at original harness and fuel flowing back to injectors again.

Another site recommended to place PMD back into original location to troubleshoot and rule out extension harness (the relocated PMD harness). I simply did not think of that.

The defective extension harness was not allowing the fuel shutoff solenoid to open, causing DTC 13 code, causing no fuel to injectors, causing no start.

I checked for operation of solenoid (at solenoid w/12V) - good, all sensors read good, etc. All that was negated when I assumed harness was good and tried to run a good PMD off a bad harness extension, since the PMD controls the Fuel Solenoid Shutoff. (Solenoid IS fine, the harness wiring itself is malfunctioning).

I am going to make a new harness tonight. Other solution would be to remove the plunger inside of solenoid since without power it wont retract. Therefore, if wire ever goes out again, the plunger cant return to the default state of down(cutting fuel to pump). I think I am going to do that also as that solenoid cost me a $200 tow to my driveway. Without that solenoid plunger, wont be a concern anymore.

I probed original PMD harness location and then the relocation harness and I was getting the same readings (from left pin to right... 0, 5.0, 12.1, 0, 0, 0.1) so I assumed it was good, especially since I had swapped PMDS in the relocation harness location.

Appreciate the help from you guys. Hopefully this solution is of use to someone in future.

[JohnC]

Don't disable the shutoff solenoid. A common failure mode of the PMD is to leave the fuel solenoid on 100% of the time. The engine will run away and you may have no way to shut it down. Same thing if the fuel solenoid sticks. The PCM monitors solenoid closure time and if it's not getting what it expects it uses the shutoff solenoid to shut the engine down. This is the "stalling" often seen.

[RGerard]

I see what you are saying John, and was concerned that about that too after some reading, but that solenoid issue has caused me problems twice now. If ever I get an emergency and it wont shut down, I can always disable the lift pump at relay and starve the IP and engine of fuel flow, no?

May not be the most delicate approach, but should work, right?

[RGerard]

Or am I misunderstanding what you are saying about engine running away.

I understand this solenoid as a backup way of shutting down IP. Key/Ignition OFF shuts off Power to PMD. PMD powers Solenoid On/off. PMD also powers IP. If no 12V to either, (truck shut off by key or disconnected batteries, no 12V), how would IP keep feeding fuel to truck to keep running without some sort of power)?

[DmaxMaverick]

The engine will run with NO help from the lift pump (the IP has in internal transfer pump). If the PMD hangs, you'll see the engine rev past 4K, instead of the ESS stopping it there. Choose your emergency, or fix the problem. If a $200 tow bill was an issue, what's an engine? (and you'll still have a tow bill)

If that happens, and you disabled the ESS, you will NOT be diving under the hood to pull a relay. It will all be over by then, or you will not WANT to dive under the hood. It happens very fast, and very dirty. Electronic intervention is JUST fast enough.

[DmaxMaverick]

Or am I misunderstanding what you are saying about engine running away.

I understand this solenoid as a backup way of shutting down IP. Key/Ignition OFF shuts off Power to PMD. PMD powers Solenoid On/off. PMD also powers IP. If no 12V to either, (truck shut off by key or disconnected batteries, no 12V), how would IP keep feeding fuel to truck to keep running without some sort of power)?

The fuel solenoid controlled by the PMD is not the ESS. It is the fuel metering solenoid, inside the pump. You cannot disable that, in any way, or the injectors get no fuel (what you were experiencing). The ESS is controlled by the PCM, powered by the IGN switch.

[RGerard]

ahhhh, got it. I thought it was just an engine that just kept running after turning the key off. Understood now.

[RGerard]

The PCM actually uses the fuel shutoff solenoid (Engine Shutoff Solenoid) to shut off engine under normal conditions (on/off) but then also uses it when it reads an abnormal/emergency condition and shuts down engine to prevent damage.

hmmm, I guess I will leave it intact then. I guess there is a reason it is there other than to drive me crazy. Thanks again guys.

[JohnC]

I guess there is a reason it is there other than to drive me crazy..

Yes! Sounds like you got it.

The Fuel Solenoid actually bleeds fuel off so you don't get a full shot. I'm not sure if the "no power" mode is full fuel or no fuel, but, either way, if it sticks you're at full throttle until you can starve the pump of fuel, which the shutoff solenoid does "right quick". So, without it, you're either on Mr. Toad's wild ride or standing by while the engine revs to it's mechanical limit. (No governor, Governor...)

[DmaxMaverick]

The fuel solenoid, by design, stops injector fuel delivery when you key off. The ESS (Engine Stop Solenoid) shuts off fuel to the IP, but it's incidental to the design during normal operation. Splitting hairs, I know.

The problem with this specific runaway is, when it happens, rarely does anyone (at the time), think about just turning off the key. As it often happens while the tranny is in gear, neither do they think of taking it out of gear (letting it rev, then shut off automatically). With the tranny engaged, it will rev shy of 4K against stall. Unfortunately, this little piece of valuable info didn't make it into the owner's manual, and few GM techs know about it (probably a lot fewer, nowadays). Runaways are extremely rare, but have happened enough that we're talking about it.

[RGerard]

Appreciate the info guys. Always appreciate learning about these things so I can understand better how it works. Makes fixing the truck easier too when you can understand the operation of the parts. Everytime I come across a new problem I haven't experienced before with this truck, kind of throws me for a loop as i research into it. I am very familiar with my truck's idiosyncrasies, but sometimes she throws a new one at me. I usually always go through the previous culprits. This harness is about 8yrs old and never gave it a second thought after I installed it with the PMD. Never thought about it going bad.

[JohnC]

The problem with this specific runaway is, when it happens, rarely does anyone (at the time), think about just turning off the key.

Just pull the compression release!