Idles rough on startup and smoking

[ThePIGSmith]

My '93 GMC Vandura 3500 van, when cold, starts and idles rough and puffs blue smoke.
If I give it just a little fuel, it idles fine and stops smoking.

I bought the van with a full tank of Diesel Fuel, approx 30 gallons.
While I have been searching and reading here, I cam to the conclusion that maybe I have a bad tank of fuel.
The owner told me that van had sat for a long period time.

Any other suggestions or ideas?

[JeepSJ]

Does the smoke go away after it warms up? If so, check the glow plugs first. Also, change the fuel filter and add some Power Service gray bottle to the tank - it has a cleaner in it and may help if things got gummed up from sitting. You could also have worn out valve seals, or they may have hardened from sitting. Change the oil and go give it a good run down the highway.

Edit - and check the timing and cold advance circuit. If the cold advance is not working, that can make it smoke.

[ThePIGSmith]

Does the smoke go away after it warms up?
It goes away as soon as give some fuel.
So, I start it, it run rough/smokes, I step on the skinny pedal, it run smooth and quits smoking.
This happens with the space of a few minutes, so the engine is not up to operating temperature yet.


Also, change the fuel filter and add some Power Service gray bottle to the tank - it has a cleaner in it and may help if things got gummed up from sitting.
Yes, I plan to do this.
I dunno how old this 30 gallons of fuel is.
I am guessing maybe 6 months or longer...I just do not know.


You could also have worn out valve seals, or they may have hardened from sitting.
Maybe, but I have owned gassers with bad valve seal and this does not act bad valves seals.


Change the oil and go give it a good run down the highway.
This is high on my list after I get the 4L80E rebuilt.
Run out all the old fuel, change all the filters, fill up with fresh fuel and Mobil1 and drive it like I stole it to blow out all the carbon/gum/gunk.


Edit - and check the timing and cold advance circuit. If the cold advance is not working, that can make it smoke.
I think you hit on something.
I need to read and study more about this, but this sounds like the anwser!

[Robyn]

This issue is not a new one.

There are several items that may be the cause of the blue smoke.
If you have a couple glow plugs that are dead those cylinders can misfire until the engine gets a little heat in it and the cylinders affected fire normally.
The other possibility that comes to mind is the injectors.
If the injectors have a lot of miles on them their "POP" pressure can be low and or the nozzle spray pattern is poor. This will cause the fuel to slobber out of the nozzle instead of a fine spray resulting in a temporary misfire condition.

Also **As mentioned** the cold advance may not be working correctly.
The Cold advance and the fast idle are tied together and are activated with the coolant temp switch and the ECM controls the on and off times.

How many miles are on the IP and the Injector nozzles??

Let us know

Robyn

[ThePIGSmith]

How many miles are on the IP and the Injector nozzles??

Let us know

Robyn

197,000 miles.

If I need injectors, which ones are recommended?
What other high mileage issues should I be looking at?

I would like add/underscore this:
As the tranny is bad in this van, so I do not know how will perform on the open road, but after I blip the throttle, it idles and run like I think it should.
Then, after it has been started, it will start right back, with no issues.
What I am describing is only when it is stone cold and before I blip the throttle.

[Subzilla]

That sounds like a nomal high-mileage 6.2 to me. My Sub and Blazer will both do this unless it's 90 degrees plus outside. But the new injectors should help if the existing ones have some miles on them. As already mentioned, the lack of cold advance/high idle function will make the smoke and rough idle much worse.