'94 chevy truck intermittent problem... !

[prginocx]

''94, 2500, 4X4, 350 V8, 4spd Auto, Xcab 6'' bed, Super shocks in rear w/external spring, AC, PB, PS, Tow kit installed, 119k miles...

This truck is my 2nd vehicle and as such serves primarily as my RV vehicle, with sometimes duty to backup my primary commute vehicle. I''m at the tail end of a vacation trip from my home in Beaverton, *or* down to Medford, *or* for a week of vacation. RV rig consists of Cabover Camper (1750lbs) and Aluminum boat (1400 lbs tow weight). Drive down last Tuesday was fine, arrived in Medford Wednesday AM with no problems and set up camp. Here is the failure scenario:

Saturday, with camper removed and boat off, I was driving in town going out to dinner, when suddenly engine died during normal driving. I was in OD mode with AC ON and REC lit cause I pushed MAX cause it was 100 degrees in Medford. Check Guages light came on, but really only BAT gauge seemed low at about 1/2 way between 9 and 14, but of course engine was OFF so what do the gauges read when the engine just quits running when you are in gear ? Battery symbol lit up also... Anyway I coast over to the shoulder, shut off the ignition, and pop the hood. Oil level normal, no odd smells *or* dripping fluids, in fact nothing looks out of place at all.

I drove over to Schucks and they ran the charging system in line test just to see if the Alternator was charging up the battery and everything seemed normal. If I operate the headlights for a while, then start the truck battery voltage goes up to about 14.5 then goes back down to 13.8 after a while say about 5 minutes of driving which seems normal to me.

On the way home from dinner failure scenario happened exactly again, but this time I just coasted over to the shoulder and then turned the ignition off and then started right up again and motored on back to camp. No abnormal readings on any gauges and engine temp wasn''t even up above 210 on the gauge.

As I''m writing this, I''m back in Roseburg about half way home with the cabover camper ON and the boat in tow. Rig ran fine all day and climbed up steep hills on I5 no problem ( I always keep it in D [not OD] when fully loaded } Ran AC all day no problems...in fact ran fine all morning with no problems. Outside Temp today was about 95, but the truck did achieve almost 210 on some of the hills coming back...

I really have no idea what could cause this problem ? The only thing that stands out is this:
1. That Saturday was extremely hot outside temp, but not extremely hot truck engine temp due to light load.
2. That Saturday was most UNLOADED running around I did with truck, but not ONLY unloaded running around. I did use the truck to launch the boat twice and go pick up firewood twice with no problems.

What the heck should I do ? This is a very new Alternator, not a rebuilt either but a NEW one. Very new rebuild water pump. New serpentine belt and tensioner...Plenty of fluid in radiator, oil pressure seems normal for this mileage of engine. I have no idea what to check ? What the hell do I do if this problem never happens again ? Why did it start right back up instantly ? ARRRRRGGGHHH !! My RV is unreliable !!

P.S. As of today I've been driving it all over the place and it works just fine. Several people have suggested replacing the HEI module just in case. Help ?

[2000CAYukon]

When the engine died, did the blower motor or radio also stop (i.e. was there an electrical loss of power) or was it just the engine stalling?

//2000CAYukon

[prginocx]

The stereo was still going, but the engine was off. The battery symbol on the dash was lit up as was the notice light in the LR corner saying " check Gauges ".
I had no power steering or power brakes for sure. One time it happened when the Headlights were on, one time they were off.

I've been driving that stupid truck all over creation " unloaded " since and haven't had any problems. Should I just shotgun something for grins ?

[gwjturner]

I had something similar to this happen to me. You mentioned a new water pump, belt and tensioner. Obviously there has been some work done on the front of the engine. Check the ground strap that is bolted to the thermostat housing. The nut that holds the ring connector for the ground strap might not have been tightened when everything went back together OR the ring connector may have been "temporarily" placed on the stud while the water pump was being replaced and no nut was put back on it when everything went back together! That's what I did and the ground strap would move, break the ground point and the engine would die. It drove me nuts for three weeks until I finally just happened to notice there was no nut holding the strap onto the stud. It's at least worth a look!

[777stickman]

From your post I would "shotgun" the ign sw. On my '98 Sub it has 5 different contacts in it that supply power to different things. Also the wiring to & from the sw in the column.

[broughy84]

The ignitions switches int these trucks are junk. If I were to start throwing parts at this without a nice thorough diagnostic period, that's where I would start.

[prginocx]

Well, it has been almost 3 weeks of continuous use and the truck works just fine, except for the extra low idle when it is warmed up, but I can't fix that anyway so I just leave it alone.

I did swap out the ignition switch, fully enjoyed the fact that it is mounted ON TOP of the steering column which made it extra hard to get out and replace. I also installed a transmission fluid temperature guage. Everything seems to work fine. I have no idea why the truck quit that day and it hasn't done anything wierd since.

I give UP !! ( It'll probably quit again when I'm 53 miles east of Timbuktu...)

[Cusser]

I just went through similar intermittent stalling/no start issue on my 1994 Suburban, and I replaced my fuel pump relay and oil pressure sender, both inexpensive. But they didn't help. My mechanic changed out the ignition module to fix it after I had it towed in. The previous week he had it and it ran perfectly, so he couldn't find the problem.

[briang0]

I have a 94 silverado. I use to stall at every traffic light. It started doing it intermittenly and got progressivly worse. I tried a lot of things it turned out to be something in the distributor I got tired of replacing things one at a time and replaced the distributor with a used one haven't had the problem since it's been over a year. Good Luck.

[prginocx]

Well, I do carry the HEI ignition module as a spare part with me at all times. I suppose if it does it again, I'll have to swap it out.

Isn't it fairly easy to exchange ?

[Cusser]

Originally Posted by prginocx

Isn't it fairly easy to exchange ?

My mechanic said replaceable without removing the distributor. I'm starting to think (at today's labor and parts markup prices) that if a component is relatively cheap and straightforward to replace, might as well do that, and know you've got a new part there, even if it is semi-shotgun. I figure just the time/effort/gas/ride to take something to the shop is about $40 in real world terms.

[CrazyHorst]

If you change the ignition module, be very sure to include the silicone dielectric grease which acts as a "thermal bridge" to the aluminum baseplate of the distributor. The aluminum base is the heatsink for the ign module and it will die quickly if it stays hot.

A GM-OEM module should come with the grease otherwise the usual dielectric stuff is what you need.

[prginocx]

I got my spare module from Beaverton Napa Auto parts, I've had pretty good luck with them....It does have a small tube of dielectric grease in the box.