6.2 with blue smoke and rough idle

[5.7L oldsdiesel]

A friend of mine has a 1987 Chevy 6.2 with 220,000KM on it.It was parked for the last 2 years until recently.It has a really bad idle.Shakes very badly and emits alot of blue smoke at idle.The blue smoke smells terrible and smells like raw fuel.It irritates my eyes quite badly.I ran the engine from a new bucket of clean diesel fuel and let the engine run with that for 20 minutes and it still shakes crazy.I did that because the fuel in the tank was stale and the previous owner used stove oil or furnance oil.I removed the valve covers and could not see anything out of the ordinary.I cracked each injector line and the engine responds when i do that.Could it be the injection pump?Can the flex ring in the pump be breaking down ready for failure?I attached a piece of line to the fuel return fitting on top of the injection pump,thinking the return was blocked or plugged and let it run into a bucket and started the engine back up and it still runs rough.It has a slight flat spot when i press the accelerator pedal.I had the valve covers off and i reattached the lines and watched the valve train at 1/4 throttle and all the rockers seem to be moving up and down the same amount.Does anyone have any idea what this problem could be?Thanks again for any help anyone may have to offer.

[john8662]

It could be a few things. When this engine is running, does it bubbles in the coolant recovery tank, or right after shut down of the engine? If so, that could be an indication of a blown head gasket, that will sure make it run like you describe. The engine can also be out of time, causing it to run very poorly. To try and correct this, you can loosen the three bolts holding the injection pump to the timing cover, and then rotate the injection pump about a lines width. You'll notice a timing mark on the cover, basically you will be trying to advance the timing, turn the injection pump towards the drivers side of the vehicle. Then tighten up the bolts then start it up again, never do this with the engine running! And finally it could just be the injection pump itself that has failed, in that its not putting out the correct pressure.

[5.7L oldsdiesel]

Thanks John for replying.I really appreciate it.I had the governor cover off the injection pump this morning and i could move the flex ring 1/8 of an inch either way.So that could be the problem.Would that be enough to cause failure?Thanks again.

[Peter J. Bierman]

Based on your describtion I think one or two injectors stuck open cousing the smoke and rough idle.
It reacts to cracking injectorlines couse some off the fuel is burning and thereby partially running.
Try some injector cleaner or remove and check the injectors.
The old bad fuel conditions coused this.

Good luck, Peter

[Robyn]

With those symtoms and the miles on the engine and given that it has sat a long time. Pull the pump off and remove the injectors. Send the lot over too the diesel house in your area and have them freshen the stuff up. This is a very common thing with well seasoned 6.2's.
Also the fuel lift pump should be replaced and of course THE FUEL FILTER.
I recently bought an 87 Blazer with a 6.2 and it was not quite as bad as you describe but it was definately not real healthy. I did the rebuild thing and OH my what a difference. Also if you are going to remove the pump take the time on that little rig and pop the timing cover off and replace the timing chain and sprockets. These wear over time and will cause the timing to go way out of whack. Its worth every penny and you will be amazed at how nice they run after you do a good freshen on the fuel injection system.