It Quit or Another one bites the dust

[ronr]

I bought my 1995 2500 series 4x4 truck a couple of years ago and have not had any stalling problems until now. It had 108k when I got it and now has 130k. It has the L65 engine and a green tag pump on it.

I turned off the highway onto a side road and it quit under power just like you turned off the key. I tried to restart it and it started right up, drove it 50 feet and quit again. Same deal on the restart and drove it 2 miles and quit again. One or two more start/ drive 50 feet/ quit and then no restart. Had to tow it home. This is the first and only trouble like this since I have had it.

Checked the lift pump, filter and fuel to IP. All ok. Cracked an injector line, cranked 30 seconds or so and have no fuel to the injector.

Checked for codes and had only a code 78 as I had just had to replace the vac pump and had not cleared the code. No other codes. My truck is I think an OBD I model as it has the ALDL plug under the steering column and using a jumper wire I can read codes via the check engine light.

So, what next? Pull off the FSD and try retorquing the transistor mountings? Any ideas?

Thanks, Ron

[a5150nut]

Its going to be a PITA to get to the FSD if it's still on the pump. If you check some of the past posts you will find how to make a custom tool.

I would check ALL electrical conections first. Including fuses. Also have someone cycle the ignition switch and check the fuel shutoff solinoid on th einjection pump. 1in dia. cylinder sticking up, two wires coming out of it. It takes an allen wrench to remove if you don't feel any cycling in it.

[JTodd]

Check previous posts for other possibilities, namely ignition switch. However, it sounds exactly like the symptoms of my FSD failure. In my case the nuts on the FSD were not loose, but you can try that first. The down side to doing that is that getting the FSD off is a big PITA, so having to do it twice would be doubly so.

[JohnC]

My '95 did exactly the same thing last Friday. (Hotest day of the year so far...) Stalled about half a dozen times, up a steep, windy narrow road, no power steering, no power brakes, no where to pull over...

Plan A was to pull the plug off the remote mount and put it back on the old one. Well, maybe if I had all my needle nose pliers and thin screw drivers with me... Plan B, wait a while.

Finally got it to run long enough to get home. Stalled half way up the driveway. Saturday I pulled the (remote mounted) PMD off and checked the screws. the loosest one was maybe 1/4 turn. I didn't have much hope. But, it's been running OK ever since. (Knock on wood). (Thanks, JD!) Put extension harness on old PMD in case.

Of course, the weather's been a lot cooler since Friday...

[gmctd]

I just pulled the FSD\PMD from the inj pump for a spot-check, after two-and-a-half years.

The nuts are still 1/4-turn tight, just as I left them, early Fall of ought one.
I had filled the cavities with white silicon thermal compound, for anti-oxidant, then remounted to the inj pump with the factory heat pad.

Highest fuel temperature thru the pump is 140deg at 200deg Engine Coolant Temps, so it has to be heat-soak temps that's doing them in.

Found the timing chain, installed two months earlier Summer ought one, totally stretched, worse than the oem chain I replaced.

Guess it's time to try some gears.

Also, JohnC - my trans is T400 3-spd with auxiliary 3-spd overdrive trans.

The engine can be 'lugged'' like a standard shift, and PCM functions can be observed under continuous loading from 1500rpm to 3500rpm, no down-shifting or up-shifting.

I think it gives a truer picture of what's happening with fuel rates, inj timing, wastegate duty cycle, and etc.

I nailed it the other afternoon at 30mph, 3rd\overdrive - 15psi boost, 78cmm fuel, blowing black smoke, headin' for 70mph, lookin' good, for a GM-8.

[gmctd]

Also - pulled the valve covers, no crumbled nylon rocker arm keepers - turbo side same color as opposite side.
Pulled the pan, no main-webbing cracks.
No accumulated dirt, metallic detritus in the pan sump.

Be a good time to slip in some 18:1 slugs. Everything clean, excellent wear patterns - be an easy in-frame upgrade.

But, alas - the lure of an under-square, long-stroke six is too great......

[JohnC]

Originally posted by JohnC:
Saturday I pulled the (remote mounted) PMD off and checked the screws. the loosest one was maybe 1/4 turn. I didn't have much hope. But, it's been running OK ever since. (Knock on wood). (Thanks, JD!) Put extension harness on old PMD in case.

Of course, the weather's been a lot cooler since Friday... Update. the hot weather is back and so is the problem. The old PMD was worthless, either because I didn't get the harness on correctly (likely) or it failed even though it wasn't being used.

New PMD today (thanks, JK) hopefully I'm good for another 100K miles. PMDs cost more than sparkplugs...

[patrick m.]

being a '95 model, dont let the ignition switch catch you off guard!

[JohnC]

Originally posted by Patrick m.:
being a '95 model, dont let the ignition switch catch you off guard! '95 model? Me or the truck?

Replaced ignition switch at 34K.