6.5L GEP - Black Smoke when accelerating

[mgFray]

Some of you might be aware of my recent saga of head/head gasket problems and getting that stuff all replaced.

I noticed yesterday that when I accelerate, there is a trail of black smoke. It's not a _LOT_, but it is visible. So I assume there is simply too much fuel going into the engine.

At idle it doesn't seem to have any issues with black (or white [unburnt]) smoke. So I'm thinking it's something to do with acceleration.

Under load (55 MPH), but not accelerating, I don't see any smoke.. but I'm the one driving so there may be some.

I'm trying to figure out what to do to start diagnosing this. The only thing I found in the TM was to check the air filter and intake (which I plan to do today. However the air gauge shows everything is fine.)

 

[spankybear]

Sounds like the injector pump maybe out of spec. Is it a turbo?

 

[Retiredwarhorses]

may simply be normal, but retarded pump timing, clogged catalytic converter, failing turbo charger…all produce black exhaust.
question is, just how bad is it? These older IDI motors will produce black smoke faintly under load and snapping accelerator.
these aren’t like modern diesel’s of today that are smokeless.

 

[spankybear]

may simply be normal, but retarded pump timing, clogged catalytic converter, failing turbo charger…all produce black exhaust.
question is, just how bad is it? These older IDI motors will produce black smoke faintly under load and snapping accelerator.
these aren’t like modern diesel’s of today that are smokeless.

" modern diesel’s of today that are smokeless."

Bro dozers say hold my beer....

 

[Coug]

The only times I see smoke in my truck are heavy acceleration or very heavy load, like trying to maintain speed while driving over a mountain pass.

If you don't see smoke other than acceleration or extremely heavy loads, then don't stress it.

 

[mgFray]

6.5L N/A

Flat land accelerating from 20 mph to 55. My foot is not all the way to the floor or anything.

I see the black until I hit speed then it appears to disappear.

with the recent head/head gasket replacement they did check the injectors and they all passed.

I’m mostly worried the injection pump is set wrong or having problems of some kind. It never had black before the recent work, but it had other problems.

 

[TOBASH]

Run injector cleaner and see what happens after a tank or two

 

[Coug]

on a related note: how does the air filter restriction gauge look in the dash? It could be something as simple as the air filter partially plugged up or the mushroom cap over the air intake pushed down a little too far, restricting air into the engine.

edit: I've also heard of things like shop rages accidentally left in the intake causing issues as well, though that's usually worse than just a little bit of smoke.

 

[mgFray]

I've put about 150-200 miles on it since getting the head gasket/heads replaced. My butt dyno seems to think it has more torque (maybe more HP?). Tomorrow I'll go out and take off the intake and air filter and just verify everything.

It didn't occur to me, but I didn't see the black until I filled up at a local station (I'd done two or three fill ups prior at another station.). Maybe I got bad fuel, or something has blocked the injectors. So I'll take Tobash's advice and get some injector cleaner and start running it through the truck. Assuming it doesn't get any worse then it already is, maybe that will fix it.

(As terrible as these things are compared to modern electronic ECU managed injectors with catalysts and sooth capture.. I don't really want to want to be the guy rolling coal down the road. I know it's not going to be super clean, but back smoke/soot pouring out isn't my thing.)

I'm not ready to tinker with the injection pump, but is there any sort of setting for fuel during acceleration vs just holding steady? If this doesn't "get better", I'm wondering if something needs to be adjusted with the new heads, etc.

Thanks for the suggestions, I'll let you guys know how it turn out after inspecting the intake and running some cleaner though it.

 

[87cr250r]

What does the nameplate on your injection pump say? DB2829-**** or DB2831-****. As others have aluded, your pump may be for a turbo engine or turned up.

 

[mgFray]

The air gauge on the dash doesn't show any real restriction, but....

Ok, went out and inspected the air filter. Has some minor debris (leaves) on it.. but not enough to block air flow. Cleaned off the lose debris.

The intake on the hood DOES look like it was pushed down beyond where it was originally installed. Loosened it up and raised it back to the top of the intake. Maybe this will help.

As for the injection pump:

White tag on top of the pump says:

5?9624
16031387 4879

the blue tag on the side, the ltitle I can read:

????? 823-4879

????? 101498????

 

[mgFray]

 

[Retiredwarhorses]

The air gauge on the dash doesn't show any real restriction, but....

Ok, went out and inspected the air filter. Has some minor debris (leaves) on it.. but not enough to block air flow. Cleaned off the lose debris.

The intake on the hood DOES look like it was pushed down beyond where it was originally installed. Loosened it up and raised it back to the top of the intake. Maybe this will help.

As for the injection pump:

White tag on top of the pump says:

5?9624
16031387 4879

the blue tag on the side, the ltitle I can read:

????? 823-4879

????? 101498????

that pump is for a 1990 1/2 6.2L Engine…

 

[mgFray]

Sounds about right. This is a 6.5L GEP that replaced the original 6.2L. So it's detuned for sure. (I was told that it was installed around 2003 by the army...). Then nothing except regular maintenance was done to the engine, until it had the head/head gasket issue that I had fixed over winter.

 

[Retiredwarhorses]

Sounds about right. This is a 6.5L GEP that replaced the original 6.2L. So it's detuned for sure. (I was told that it was installed around 2003 by the army...). Then nothing except regular maintenance was done to the engine, until it had the head/head gasket issue that I had fixed over winter.

wrong pump for a 6.5 detuned…that motor should have a 5209

 

[mgFray]

Ok, so what does this mean for the engine having the wrong pump? Down on power, bad fueling or?

Also a quick search of ebay, I don't find any DB2831-5209, but I do find DB2831-6278 which someone is claiming is the replacement?

 

[Retiredwarhorses]

Ok, so what does this mean for the engine having the wrong pump? Down on power, bad fueling or?

Also a quick search of ebay, I don't find any DB2831-5209, but I do find DB2831-6278 which someone is claiming is the replacement?

correct, 6278 is just a newer pump model, it replaced the 5209…
as far as “what does it mean”? It means you have the wrong pump per the application chart/TM for that motor…what I’ve generally found on the 4879 pump is when used in a 6.2 before 1990 1/2 model engine, is the timing has to be advanced like crazy to get them to run right…and even than, lots of unburnt diesel smell.
on your truck, try advancing the timing…

 

[mgFray]

The vehicle is running fine. Engine feels smooth, feels like it has enough power, etc. Only think is the black soot on acceleration. I suppose if the timing is advanced too much (or the pump has been screwed with) it could cause the over fueling and the black soot? (I'm grasping here, I really don't know much about diesels.)

 

[TOBASH]

I think RWH has identified the issue

 

[Retiredwarhorses]

The vehicle is running fine. Engine feels smooth, feels like it has enough power, etc. Only think is the black soot on acceleration. I suppose if the timing is advanced too much (or the pump has been screwed with) it could cause the over fueling and the black soot? (I'm grasping here, I really don't know much about diesels.)

You don’t know very much about diesels but you’re inclined to believe having the wrong pump is ok? alrighty than….
Its not totally uncommon to see the wrong application pump in a hmmwv and it runs…my observation is that of a technical one, my shop would never install that pump on that engine…