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1997 GMC 3500 6.5 Diesel Stopped Running Today

K

kurtis103

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Location
Central Pennsylvania
Hello All,

I was working on my GMC Today and replaced the Glow Plug Relay. The truck was warmed up before hand and ran well. Replaced it, and it started promptly. The truck was idleing for a short period then made a strange noise, and idled for a couple of seconds then stalled. It has not started since. I can turn it over, and it does not start. It tries to fire every now and then but sounds like things are not timed or perhaps my timing chain has skipped a tooth. The truck has 255K miles on it and many of them have probably not been kind. i have had it for 20K miles.

I am a half-ways decent DIYer but rather than just tearing it apart, I was hoping for some tips or short cuts to more firmly diagnose things. Or has anyone had a similar experience and how often does the timing chain skip on these?

Also, if I do decide to take it apart and pursue the job, what else would it be smart to replace? I am not looking to bolt on new parts just because, but want to be smart about it.

Thanks in advance
 
Kurtis, pull up the troubleshooting checklist in my signature and go through it.. There are a ton of maintenance check items there, and knowing how they are saves us from asking a pile of repetitive questions.

Copy/paste it into a new post in this thread, fill it out as best you can, and it will give us a "look" at your truck.
 
I'd check grounds, fuel shut off (connections, fuse, and if it even works), next make sure the pmd is good and the harness is in good condition.
 
Problem: Explain your problem in concise language (ie: Cranks but won’t fire). Cranks and Fires (very intermittantly) but does not start or come close to starting

Demographics: tell us about your truck and your ambient conditions:

- Year: 1997
- Truck model and class (ie: c2500) 3500
- Automatic or Standard Auto - and Auto 4WD
- Mileage: (indicate miles or km) 255000 Miles
- Replaced parts and mods (IP, PMD, chip/PCM, TM, injectors etc) PMD couple months ago
- Model: ‘S’ or ‘F’ engine, NA or Turbo, EGR? F (Diesel)
- Ambient outside temp: (indicate *C or *F) 40 F
- What fuel are you using? (#1 Diesel, #2 Diesel, Bio, VO, WVO, etc) Pump Diesel (though truck does see well heated wvo)
- What fuel additives are you using? None
- Where are you located? Pennsylvania

General maintenance: inspect and evaluate the condition of each. When were they last changed?
- Air filter 2 yrs ago
- Fuel filter Unknown
- CDR Valve? Unknown
- Coolant – last flushed/replaced at 2 yr ago
- Oil – synthetic/regular, changed at 245K miles
- Batteries – state of charge, (matched set) replaced at Both are new in last 3 months
- Battery cables and grounds (removed, cleaned and tightened): last 3 months
- Glow Plugs - how many miles on them? Within 500 miles What type? AC Delco
- Injectors - last changed at Unknown


History: (Describe how the problem first appeared.)
- What were you doing when it happened? Replaced Glow Plug Relay, Started Truck, Idled fine for 10 minutes, then stopped
- How was the truck running fine before this problem appeared? Fine
- Has this problem ever happened before? No
- Describe any related factors that might be part of the problem. Old Truck
- Have you checked for DTC (Diagnostic Trouble Codes)? (Y.N) Y And? None


Diagnostics:

1] Starting:
1a] Does the engine start? No
1b] Does the engine crank over? Yes
1c] Are your batteries fully charged? Yes
1d] Have you removed, cleaned, and tightened all battery connections? Yes
1e] Does your Wait to Start light come on for a time? How long? 4-5 secs
1f] Does your glow plug light come on? ____? Same as Wait?_____ For how long? _________
1g] Do you see smoke from the exhaust while cranking? What color? No
1h] Does the Service Engine Light Glow during Start/bulb check? Yes

2] Fuel Issues (if not running):
2a] Can you hear your lift pump working? Not Sure (A two man test)
2b] Do you get a steady flow of fuel from the water drain (T-handle) ? _________
2c] Loosen the inlet line from the IP – is fuel coming out (Lift Pump on)? ___________
2d] Loosen an injector line and crank the engine - does fuel come out? _________
2e] Do you hear a vacuum (hiss) when you remove the fuel cap? ___________

3] PMD / IP Issues
3a] Location of PMD (on pump, on intake, remote mounted) On intake manifold top
3b] Condition of Extension harness (if used) Vendor or Homemade? Decent - probably Vendor
3c] Condition of grounds / ground wires to IP / PMD. Check Harness. Looks Decent
3d] PMD Make: Newer Grey Type
3e] PMD Age: ?

4] Stalling Issues - N/A - does not start
4a] Do you experience stalling only when hot? ____________
4b] Does it stall under particular circumstances? (ie hit bump, or on accel) ______
4c] Does pouring cool water over the IP seem to help with restarting? _________
4d] Is stalling momentary (engine recovers)? _________
4e] Does SES light come on when engine hiccups? _________
4f] Does cruise control quit working when engine hiccups? ___________
4g] Does re-starting seem to reset engine, restoring cruise and power? _________
4h] Changes to dash lights or instruments during stalling events? ___________

5] Running Issues - N/A does not start
5a] On cold start, does upper rad hose get hard before engine warms up? _______
5b] Any bubbles or oil film in coolant overflow tank? ______No_
5c] Any white slime on oil surfaces (dipstick, CDR, oil Fill cap)? _No_________
5d] Excessive white smoke from exhaust on cold start? ___Perhaps (before this issue)______
5e] Excessive black smoke from exhaust under hard acceleration? __No________

6] Performance Issues - N/A does not start
6a] Do you have gauges (boost, EGT) ? No
6b] Maximum boost under load? ____________
6c] Have you added a performance PCM (reflash) or Chip? No
6d] Have you changed exhaust / downpipe / crossover? Yes - recently
6e] Wastegate – mechanical or vacuum (OEM)? OEM?

7] Temperature-related Issues:N/A
7a] Single or dual thermostats? ___________Single?_
7b] Have you replaced them lately? No Manufacturer of replacements? _________
7c] Have you pulled and cleaned Radiator and coolers lately? ____No________
7d] Have you replaced the fan clutch? Manufacturer of replacement? _No_______
7e] (winter) Have you tested your antifreeze? Good to what temp? ___No_______
7f] (winter) Are you using a winter grille cover? __No_________

List and describe any other factors which are not addressed in this checklist. We can’t see, hear, smell, or touch your truck, so the more descriptive information you can give, the more likely it is that somebody can assist you.

I purchased it 2-3 yrs ago and it had some hard miles on it. The PMD that is currently on it was the newer Grey type and came with the truck. I had throttle control issues this last summer and it finally got bad enough that I replaced the PMD and a couple of other throttle related parts. The PMD cured it then.

Now It does not come close to starting, fires once in a while, but acts like timing is off. As mentioned above, it was idling, then a noise for about 2 secs, then idle for a couple of secs, then nothing. The noise could have been a timing chain grinding or slapping on the cover, or not. I suppose that a complete lift pump failure would be a possibility.
 
A PMD on the intake could be suspect regardless of age. Mine lasted 3,000 miles. Is it plugged directly into the factory plug? Or is there an extension, some extensions are NFG.

When you put the new PMD on did you change over the resistor?
 
If you could try a known good PMD before replacing any parts, that is what I would do.

One other thing to do is remove and clean all the grounds, there are 2-3 on the trans dipstick that could cause your problems.
 
Your problem may not be caused by your glow plug relay change, it may just be coincidental. Start with the easy stuff first.

1. Check to make sure the LP is purring. it is located inside the frame rail under the driver seat. It is a cylinder shape with a plug connected to it. only about 3" long or so. The easiest way to check this by yourself it to open your driver side window, leave the key in the ignition in the off position, get out and close the door. Reach in and turn the key to the on position so the plugs start cycling and the pump starts pumping. Now get down close to the ground and listen for the pure. If you don't hear anything feel the pump it should be vibrating. The other alternative is to get someone to turn on the truck while you're on your back looking/feeling the LP when they turn it on. If it doesn't vibrate or pure then it isn't working or the relay to it isn't working. I don't know where the relay is located but I'm sure someone will chime in if the pump isn't working. The easiest way to verify that the relay is working is to unplug the pump and connect and ohm reader to it to the trucks connector to see if it has continuity. REMEMBER!!! If it is purring and vibrating then the relay is good but the pump isn't necessarily good. Pumps can still purr and be bad.

2. If your pump is purring go to the t-valve located in the front of the engine on the passenger side of the center/middle of the truck. It has a hose coming out of it. The hose should be anywhere from a foot to 18". Pull the hose over the top of the engine so you can put it in an empty bottle or can. Open the t-valve and turn the key to the on position. You should get a steady stream out of the hose. If you don't then Your filter is clogged or possible the tank sock is clogged. If it is a good stream then move on to the next step.

3. PMD / Cable. You need to do this even if the above steps fix your problem. Purchase a new PMD cooling kit/ext cable from preferably one of the supporting vendors on this site. Install it behind your license plate inside your bumper. The cool air entering into the nostrils of the bumper will keep the pmd cool and it shouldn't ever be a problem for a long while.

Do these 3 steps and get back to us.
 
Rodd,

Thanks for the diagnostic steps, things just got a bit simpler.

My lift pump does not appear to do anything, when the key is turned on or when the engine is cranked. I also opened the fuel waste gate and never have any fuel (with key on or cranking) which seems to confirm that the lift pump is not doing its thing. I read somewhere in the web that the lift pump will not come on by just turning the key to run, but rather you have to crank?

Also, I read somewhere that the oil pressure sensor/switch must function for the lift pump to be activated. Apparently the OPS is nearby the Glow Plug Relay so perhaps I did something stupid while switching the relay. If this seems like a possibility to someone, please let me know. Otherwise I have a BIG coinsidence with the lift pump failure.

It seems that you must lift the fuel filter to get to the OPS, so the next dry and reasonably warm day I will check for power on the lift pump and then look for the OPS.

If you guys have any other advice please chime in. (I also have a spare PMD ordered).

Thanks
 
Check the ECM-B fuse? or other fuses?

There is a thread at DP that he got 2 BAD NEW GP controller.
Also, he tightened it too tight on the big connectors causing it to make bad contact.
The pins on the harness was not seated properly also.
 
JMJnET,

I had also checked the fuses today - Lift Pump and ECM and everything else in the box. Had also seen the other thread on the GP RELAY overtorking, so I confirmed the voltage at the GPS, they are now working. Also tried plugging in the block today just to make sure it was not a hard start issue.

I just ordered a lift pump. After reading another thread about symptoms when it is failing, I convinved my self that I might be incurring them (hard starting, no power, heisitating when cold, etc.)
 
If lp isn't working check it by jumping it off of a spare battery (or other 12v source) and see if it comes to life. This would indicate a bad ops.

The lp SHOULD be triggered by the ecm on a 97 and run with key on. In this case you need to confirm the lp is actually dead. If the lp does come on then you will be back to grounds/wiring/ecm.
 
x2 with Tanman, also while it is on 12v direct source, you can try if you can start.

If not, then you have confirmed that LP is bad.

Did you check the fuel filter?
 
Guys - thanks for the advice. It will have to wait until I have a weekend with decent weather. Will post what I find when I find it in a few days or weeks... You know how it goes.

I will check the voltage on the LP and probably try to jumper it then see where things lead me. I really need to move the truck before snow....
 
Since you only changed the GP relay I suspect you possibly pulled the OPS wires? Confirm its still pluged in.
 
Do you know where the jumper wire is for the lift pump?

There is a spade connector in between the under hood fuse box and the firewall. It caN be hard to find sometimes, even when you know where it is. I prefer to use a fused jumper wire to connect it to the posts on the back of the fusebox
 
I built a harness for mine that hooks to the battery posts and has a lp connection on the other end. I will look for the other jump location. I built 2 of these harnesses for my trucks.
 
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