95 K3500 stalls, no start, read on

[FarmerDale]

I have an aggravating problem with my truck. It started stalling with no start about 5 weeks ago. I cleaned the grounds, but no improvement. After 2 new FSD's, I got a warranty IP. 5 miles from the dealer, it stalled and had a DTC 35, but after a quick shift into neutral it was idling and I got home w/o anymore troubles. Since then it has had intermittent stalls, and if it is idling it will die. Restarting is impossible until I unplug the FSD and reconnect it. Sometimes I get to do this routine 4 or 5 times until the truck decides it will run and be normal for a while.
I replaced the OPS on Fri, but drove no more than 2 miles before another series of stalls. I pulled the codes and had a 35, 84 nad 99, plus a couple other remnants from the IP install. This morning I erased the codes, cleaned the 14 pin firewall connection and OPS switch and the connector for the APP module. I just got back from a short drive and had a couple sputters, a brief stall with engine dropping to idle speed, then back up, then with cruise on, a stall with SES (code 35), engine came back at idle, but resume on cruise then was 53 instead of 60, as if I had shut off the cruise or key. The truck died just before I switched the key off, and would not restart when I moved the steering column in different positions. :confused:
Now I am leaning toward the ignition switch, but am certainly open to more suggestions. I don't think it is prudent to just throw new things at the problem w/o good logic and experience behind it.
Thanks much and Happy Easter!!

[ucdavis]

1) Ignition switch is IIRC not much $$, and w/118k IIWme I'd settle that question w/a new one. I don't think this is in the R&R guide, but it probably should be (MP??)
2) W/118k you're still about 2k from evaporation of warranty. Your call on the local dealer support.
3) Have you tried the FSD nut tightening trick? Remove FSD, pry diamond-shaped caps off back w/screwdriver (they come off easily) & tighten the 1/4" nuts you find to snug; some put a drop of blue locktite on for good measure. Then reassemble. The connection the transistors make to the PCB seem to be more fragile if these nuts are loose. FSD failure won't ordinarily set a DTC, but as much hasle as you're having, again, for notalotta dough, why not make sure.
4) the series of bizaro CC/stall conditions argue for grounds more than other syptoms to me, orrr you are getting APP codes (84 & 99) which give odd combinations of fuel delivery randomly, which could contribute if APP signals are sometimes w/in tolerance for foot action but not what your foot is actually reqesting; I've heard tell of curing these by driling a small hole in Accelerator Pedal Position aluminum housing (don't just drill till refusal as the potentiometers inside will get damaged if you nick one), squirting it full of contact cleaner, blowing it out w/needle air nozzle, bake till dry inside, cap hole w/JBWeld or equal & reinstall.
5) If the above doesn't work, attack the grounds starting w/under dash then engine stuff to chassis & clean, brighten & tighten.

[patrick m.]

after a stall, and your attemp to re-start is unsuccesfull, is the "service engine soon" lamp on with the key on?
during the next stall, switch the ign off, wait a few seconds, then switch it back to "run", watch for the S.E.S lite, it should come on with the key in run. Also should come on during "crank" then go out shortly after start-up.

95 models seem to have bad luck with ign switches, ive been there too.
good luck.

[FarmerDale]

ucdavis - underhood grounds were all burnished and reattached within the last 1k. Haven't found the underdash one to get that one up to specs. I will get a switch tomorrow, and also have a PCM coming in - with a rap on the glove box I could get it to start and run for a short time. The switch will go in first, but I need the truck early Wed, so I had to commit on at least a restock fee on the PCM.
Also truck has now advanced to 119.5k, but since IP replace didn't resolve problem I am not afraid to go back and go through it again under warranty. Also a friend in same town has a diesel repair shop with some 6.5 experience.

Patrick m.
after a stall, and your attemp to re-start is unsuccesfull, is the "service engine soon" lamp on with the key on?
during the next stall, switch the ign off, wait a few seconds, then switch it back to "run", watch for the S.E.S lite, it should come on with the key in run. Also should come on during "crank" then go out shortly after start-up.
Following this suggestion - everything is normal except the engine won't fire. The weird thing is that each time I unplug and reconnect the FSD I at least get the engine to fire. No other sequence will accomplish anything other than a long period of cranking.

Question - if I get the switch can I just let it dangle from the steering column temporarily to see if that fixes it? I am not messing around with that explosive device that is in the center of the steering wheel.

[FarmerDale]

Forgot to add that I haven't tightened the nuts on this FSD, but the problem was occurring on the last 2 new FSD's, even after a tightening procedure, so unless it is a baaaad batch....

[Tony J.]

I am not messing around with that explosive device that is in the center of the steering wheel. [/QB]I don't think 1-tons were required to have airbags (and therefore are not installed)- at least back in 95. Seems I ran into that info when researching prior to purchasing my 95 a couple of months ago...

[gmctd]

Symptoms are of intermittent electrical connections - ign switch, and wiring harness connectors.
Unplug, inspect for corrosion\oxidation, clean and reconnect all electrical connections in engine bay, and cab, before installing the replacement PCM.
Some fixes are the connectors, obscured as the part is replaced and connected.

DTC-35 can be bad fuel and\or insufficient fuel supply to inj pump.

[patrick m.]

Farmer Dale, yes you can disconnect the ign switch under the dash, and connect a new one and operate the new switch with a screw driver (or something).
my 95 doesnt have an air bag, eventhough the steering wheel looks like it does.
having said that, the wheel doesnt have to come off to replace the ign switch on a 95, just the two cover halves ;)

[FarmerDale]

would it be, could it be the crankshaft position sensor.

I am clutching at straws, but the truck doesn't even fire now. Cranking speed is fast enough, but no sweet diesel noise. No speed on tach either, but I can't remember if it showed during crank (also, that's off the alt, isn't it?)

Have to use the old '87 K1500 gasser to get the pigs to town tomorrow morning. :mad:

[tom.mcinerney]

Farmer--You've done your homework, and got good advice above. Do not despair when the intermittent transitions to constant failure; now the problem is solvable, though inconvenient!
The Ig-Sw; Crank sensor; PCM sounds like a respectable replacement sequence. Randee-Redwood's tech manual indicates the FSD and fuel shutoff solenoid both powered directly by Ig Sw.
Your connector R&R experience points to harness problem.
Most engine sensors and other underhood electrical gear are grounded through harness connections. But the glowplugs, and the FSD depend on block grounding. (Interesting that those members with loose FIP mounting bolts had timing issues before firing problems).
You replaced the OPS. Didja check pressure from LP at the filter drain valve up front? Charlie P had a failed LP which sounded OK; UCalDavis mentions that fuel bubbles trigger optical sensor probs...TBOGEMIREP notes that a clogged filter will mimic FSD failure.
Regards to the trusty 'ole gasser! It's times like now that reliability trumps efficiency/power!

[Randee of the Redwoods]

Wow. I feel so "included" now. Someone actually mentioned my name in relation to fixing a difficult problem. But seriously...
Say the word and I'll whip out my manuals and looks some stuff up. In total, I have the 94 full service manual, emissions and drivability supplement, and a keen little job called the GM Training Manual. Between the 3 I should be able to help you locate just about anything you are looking for. I'll be gone Sat but I'll check back regularly.

[FarmerDale]

Thanks all for your help. I sent the truck off to a diesel repair shop of a friend. They were first going to look at the connections, including the PCM connections on the firewall side. They had another 6.5 with these problems in which a rodent had set up housekeeping. I could have kept tracking it down, but planting season arrived a week or two early, and timeliness pays in that endeavor. Will post the results.

On edit - just back from shop - They traced all electricals functioning to IP, but nothing happening :mad: . Caught them before it went too far and will let dealer try to get a good warranty IP this time. :eek:

[ 04-16-2004, 06:41 AM: Message edited by: Farmer Dale ]

[FarmerDale]

One last post for me to wrap this up.

Dealer got truck. Said OPS (10 miles on it) was no good, and lift pump didn't run wired direct. Also, the cooler I had (a cheapy from SSdieselsupply off eBay) had crappy pop rivets holding it together and they would drop they ground from time to time. Also a couple pins in the FSD connector were loose, so they got adjusted. Lift pump replaced, new OPS, ground wire for FSD run over to intake side of cooler, new fuel cap and it works great! (plus a few $$$)

I am not sure how those electrical gremlins dropped out so nicely in the 1/2 mi push the truck got from one shop to the next, but when GM is stingy on warranty work I guess they get a few more ideas going.

Unfortunately, GM tech services wouldn't let the timing offset be set any more advanced than -0.25. Obviously this adds a few more revolutions to start it and I am not happy. I will lwt it ride for now, but will look for opportunities to improve it in the future.

[tom.mcinerney]

F-Dale:
Nice troubleshooting work by dealer. Sorry for detuning. Hope planting going well. Do you post in other forums about other equipment?

This isn't first time:
1) Indications that bad LP can draw enough power to debilitate other system components...
2) Indications that damage to the FSD connector dooms subsequent FSD operation...

[FarmerDale]

Tom,

was suprised the dealer did that well, and the mechanic doesn't even specialize in diesels. He is slow, however. Also, it easier to trouble shoot when the LP doesn't run, even hot-wired. LP always ran and had good fuel flow for myself and other diesel shop.
I monitor a couple equipment boards, but have not been active in posting. Do you have any suggestions??

Thanks to all on the DP for your help.