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1995 Yukon - Strange Stall

BigBen

BigBen

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OK, had a new one that hit me today.

1995 Yukon GT, 350 engine (all stock), 265,000 miles.

We were sitting at a red light idling, nothing strange going on.
The truck just simply shut off like you turned the key off. No stutter, no struggle.

Pushed it into Park, turned the key to off, then it started like normal. Back into gear and drove away like nothing ever happened.

No 'check engine' light, nothing.

Anyone got any ideas where to start looking to chase down this gremlin?
 
my Burb did some things like that to me at random, just shut off for no reason, even while driving, it would simply shut down, but before i could really react, it would fire back up. It did this several times over a period of about 3 months till finally one morning it just wouldn't start.

Turned out to be a fuel injector was going bad.
 
I had a problem like that in a chevy astro van. It was the ing switch wiring that went through the column.
 
EIB8400 said:
I had a problem like that in a chevy astro van. It was the ing switch wiring that went through the column.
Click to expand...

Don't know if this matters, but the instrument panel and everything (radio) stayed lit and working until I turned the switch back to re-start it.

-Ben
 
My old 89 LD K2500 would just die going down the road sometimes, then usually restart right away. It was the fuel pump going bad.
 
79rustyk10 said:
My old 89 LD K2500 would just die going down the road sometimes, then usually restart right away. It was the fuel pump going bad.
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Hmmmm... interesting. It didn't stutter or anything, but I wonder if that might be it....
 
It's a possibility, that's what i thought too, so i replaced my fuel pump first, then it still did it again a few days later, so i replaced the fuel pump relay, again, still did it, i was not wanting it to be an injector because of the price for new ones, but unfortunately, it was in my case.
 
4xcrazy said:
It's a possibility, that's what i thought too, so i replaced my fuel pump first, then it still did it again a few days later, so i replaced the fuel pump relay, again, still did it, i was not wanting it to be an injector because of the price for new ones, but unfortunately, it was in my case.
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Well crap, this is sounding like it's time for me to figure out how to diagnose fuel system problems. Off to my Haynes manual I go tonight.
 
GM ignition modules are famous for going bad. I would swap out the module (they are only about 40.00) and see what happens. I would throw the old one in your glovebox as a back up in case you need it in a pinch. The other item that goes bad but not nearly as often is the pick-up coil located within the distributor (have to remove the distributor and take it completely apart in order to change this part).
 
4X4HIGH said:
GM ignition modules are famous for going bad. I would swap out the module (they are only about 40.00) and see what happens. I would throw the old one in your glovebox as a back up in case you need it in a pinch. The other item that goes bad but not nearly as often is the pick-up coil located within the distributor (have to remove the distributor and take it completely apart in order to change this part).
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Good thoughts. On my '85 the truck died and didn't restart when the ignition module died. Could it also do an intermittent failure? I replaced this one about 80k miles ago to be safe on a trip to Quebec for Caribou hunting. I could always swap the old one back in to see what happens if this keeps popping up.

Pick-up coil... hadn't thought of that. I may have to take a look. I changed the one in my '74 and I don't think the distributors are THAT different....

-Ben
 
Ign modules and pickup coils will do some weird stuff, but usually aren't long for the world once a problem surfaces. Might give your grounds a good looking over as well. Would be a cheap fix.
 
It did it to me again this morning. Truck was running fine, then when coasting to a turn, truck just turned off, no stutter/shake/sputter or anything.

Put it in park, switched it off, and re-started. It started like it normally does and ran no problem from there.

This has never happened before, but now 2 days in a row. I've got to get in there and figure this out.

OK, maybe it's time for some more vehicle history detail. I've been reading through the Haynes manual today and realizing I don't have the tools to diagnose fuel pressure at my disposal.

From what I can tell, my main culprits could be:

Fuel Pump (Still the original at 15 years / 265,000 miles)
Fuel Filter (I change 'em every 20,000 miles, this one is pretty new right now)
Fuel Pump Relay (Still the original - I have another one in the glove box I could put in)
Fuel Pressure Regulator (Still original and untouched)
Fuel Injectors (Still original and untouched)

Ignition module (replaced 5 years, 80,000 miles ago with an AC delco one from the dealership.)
Ignition Coil (Replaced with AC/Delco at the same time as module)
Pick-Up Coil (still original)

Plugs/wires/cap/rotor are always changed religiously with AC/Delco parts. The latest set has about 5,000 miles on them.



I hate to just start swapping parts and praying. This thing is my daily driver and I need it to run. Anyone got any good diagnosis tricks that I could do to start to narrow all this down?

I suppose the other option would be the sledge-hammer approach and just change everything all in one shot. But OUCH that would be expensive.

Thanks again,

-Ben




PS> One little history thing. Ever since I bought the thing at 2.5 years old and 57,000 miles it has had this one quirk. Probably once or twice a year when I'm sitting at idle it will start to cough and sputter...almost not run at all. I rev it up and after about 20 seconds we go along with life like nothing ever happened. It's only happened once or twice a year and I've never figured out what it was. I wonder if this is related?
 
in my personal experiences with these fuel injected engines, if you are running your truck with 265k miles, with the original fuel pump, you are WAY past the average operating range on that thing, you got VERY lucky with that thing :)

also i am running at 256k on mine, and the one injector problem i told you about happened at about 230k,,,
 
4xcrazy said:
in my personal experiences with these fuel injected engines, if you are running your truck with 265k miles, with the original fuel pump, you are WAY past the average operating range on that thing, you got VERY lucky with that thing :)

also i am running at 256k on mine, and the one injector problem i told you about happened at about 230k,,,
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Point taken on the fuel pump.
An old-timer told me a while back that most people run into trouble with these pumps since they only run around on 1/4 tank. Claimed that filling the tank each time would keep it cooler and make it last longer. Don't know if he knew what he was talking about, but it sure seemed to work. (That, and keep changing the fuel filter)

Anyway....

I don't want to sound too stupid here, but is there a way to check the injectors? Is it a visual thing? How do I know if they need to be changed?
 
Planning to check grounds (Hopefully tonight).
I'll have to take a look on this truck to see what's there.
I'm assuming that most electronic parts need to be grounded to the engine, and probably a strap from the body to the engine?

-Ben
 
If it is only doing it while coasting or your foot off the gas, it might be the IAC acting up and shutting off the idle air with the throttle body butterfly fully closed. James
 
OK guys, a little more information.

Over the holidays I looked through it and couldn't find anything 'wrong' with it as far as connections or grounds.

For good measure I put in a full tank with dry-gas and injector cleaner to see if it would help. Not much change yet.

I've got the stuff to build a WIN-ALDL cable and see if I can do a data log when it dies.

Of interest, she threw her first code today:

34 - MAP sensor.

Could a bad MAP sensor cause all of this?
Would it be worth changing it out to see if it helps?

-Ben
 
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