Hard to start after truck has been running

[anp4god]

I've searched the threads but not found the answer yet, so here goes.
About 3 or 4 times over the last month after coming out from a store, the Suburban hasn't wanted to start. It will crank fine. It also seems the glow plugs aren't going through their time cycle and I don't think the lift pump is running. I've messed with the alarm system some but haven't ruled it out yet. It reminds me of if you try to start a car and the security system won't let the ignition engage, just allow it to crank.
After a few attempts and popping the hood, checking conncetions, etc. I get back in, hit the key, see the glow plugs time cycle normal, hear the lift pump run for a few seconds and it fires right up like normal.
No other symptoms. It runs excellent.
Should I be looking at the alarm system or fuel shut off solenoid? OPS isn't in the picture until it's running, right? Will the lift pump fail like this? Last time it happened, I had only driven a half a mile or so, the engine was warm from a previous trip, but the PMD was cool and I had only been in the store for about 10 minutes.

Thanks.

[racer55]

Ignition switch burning out?
Bad connection at the fuse for ECM B fuse?

[anp4god]

Could a failing ignition switch allow it to crank but not go through the glow plug and fuel pump cycle?

[racer55]

Sure the ignition switch is a multi contact switch in this aplication.

One set of contacts for the starter,one set for accessories(radio,fan,instrument cluster)and one more for the power to the ECM and probably a couple of other things like the ESO and PMD,ect.

Any one of those contacts gets warped form high current flow or burnt/arced it will have an effect on that system,I figure the plastic melts some from excess current flow that it was not designed properly for and the contacts loose tension-then the current flow increases from higher resistance and it melts some more untill it no longer can maintain constant contact.

[anp4god]

Just an update, still haven't figured this out yet.
Yesturday and today once each day the truck died within a minute of startup. Today it took a minute or two to restart. First attempt it just cranked over. Waited for a couple minutes, cycles the alarm and it started up and drove fine. The starting and dying problems have occured while running errands around town. The truck isn't hot, but it is up to operating temperature. Weather is mild, also.

Any new ideas?

[racer55]

The theft system recognize the key you are using?

[anp4god]

The theft system recognize the key you are using?

hmmm...I have 2 sets of keys. Maybe I should make a note of which set I am using to see if that has an effect. I have yet to have a problem on the first start of the day. If that has anything to do with the problem.

So far, it's so intermittant that I can't really troubleshoot it.

[DaveBr]

Sounds like your PMD is in the beginning of the end.

[anp4god]

Sounds like your PMD is in the beginning of the end.

Maybe, I had it fail once, but it didn't act anything like this. I did remote mount the new PMD, but I went with the heat sink mounted to the intake. Why I think it's something else this time is that the glow plug time cycle doesn't take place when I turn the key, also the fuel pump doesn't run. The PMD doesn't have anything to do with either of those to my knowledge.

[ToddMeister]

Sounds like you are losing power to the ECM, make sure the ECM fuses are pushed in tight, maybe even replace just to rule out an intermittent fuse.

Could be ignition switch, too like others have suggested.

[a5150nut]

How's your ignition switch? Not the key but down on the steering column.

[Warren96]

You have my vote for another bad ground connection on the passenger side of the intake manifold.

[anp4god]

You have my vote for another bad ground connection on the passenger side of the intake manifold.

I still haven't dug into this any further, but need to soon.

Question, what weight Mobil 1 do you use in your differentials and transfer case? I need to change my but wasn't sure what to use.

[DmaxMaverick]

I still haven't dug into this any further, but need to soon.

Question, what weight Mobil 1 do you use in your differentials and transfer case? I need to change my but wasn't sure what to use.

75w-90 for normal use.
75w-140 for extreme (hot) climate and/or continuous/heavy towing.

Transfer case gets Dexron III ATF. Mobil-1 is an excellent choice.
If your TC has "Auto 4x4" feature, you'll need GM "Auto-Trac II" fluid.

[anp4god]

Checked grounds on rear of intake manifold, they didn't look bad but I change them anyway being a avionics technician. The next day, after sitting for over an hour the truck didn't start. This time, though, the glow plugs would cycle and lift pump ran. A few hours later after getting back from a conference (A friend picked my up) it started right up. I pulled out the ECU or PCM and checked the pins and didn't see anything wrong. My computer OBDII program didn't show any codes or pending codes. I have the full shop manual so I'm going to follow the troubleshooting chart first but probably will end up at the ECU.

[racer55]

Sounds like you solved a few problems by repairing the grounds.

Since you remote PMD is on the intake,is the IP harness ground still on the IP where it belongs or fastened to the PMD heatsink?

If on the heatsink-return it to the Top of the IP-otherwise PMD is likely cause of the problem.

[anp4god]

I left the PMD ground on the IP.

[anp4god]

Well, no codes, checked ECU connections, changed ECU grounds just in case, removed security system, still having problems. The more I started looking at all the data, the more I suspected the PMD failing again.

Contacted Accurate Diesel who sold me the bulletproof Stanadyne 18 months ago, and found they don't carry it anymore due to so many failures. The helped me out with a HD Dtech PMD and 6 foot cable so I can relocate the remote kit from the intake to the front bumper. I did that this weekend and haven't had any issues yet. I think the problem is solved.

Thanks for all the input.

[Yukon6.2]

[Q The helped me out wi th aHD Dtech PMD and 6 foot cable so I can relocate the remote kit from the intake to the front bumper. I did that this weekend and haven't had any issues yet. I think the problem is solved.

Thanks for all the input.[/QUOTE]
Hi
Do yourself a favor and get a spare PMD.
That way when the DTech starts acting up you can change it.
The way to chose between DTech and Stanadyne is to toss a coin.
I'v had a black stanadyne go bad,two Dtechs in a row and am now on a used black stanadyne.My next choice to try may be the grey one.Unless i have some spare time then the DB2 thats waiting on the self goes in.
Good Luck
Thomas