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6.2L Diesel in need of Help

CUCV2

CUCV2

5/4 ton fun
Joined
Mar 22, 2007
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I was driving the M1009 on about a 100 mile round trip the other day. It ran great for most of it. I made a stop towards the end and shut it off for about 30 minutes. Started it back up and it hasn't been right since. It only has about half the power and no longer makes the loud diesel sound. Sounds like it has no compression any more. Any ideas what could turn things around so quickly?
 
If it isn't the fuel pump it's the supply of fuel. When's the last time you changed the fuel filter?
 
Lift pump.
Filter.
Maybe the IP is going. Got any fuel puddles underneath it?
 
How recently did you fuel up before the problem started? I've been on a roadtrip and got a bad tank of fuel and it started running pretty bad within a short distance. Changing the fuel filter and a fresh tank of fuel got it back to normal.
 
check ur oil if the fuel pump is going out it could be filling ur crank case with diesel had it happen to me the same way a week ago. i was almost a full quart over full.
 
super k said:
If it isn't the fuel pump it's the supply of fuel. When's the last time you changed the fuel filter?
Click to expand...
Never. Probably should replace that regardless. Thanks.

AJMBLAZER said:
Lift pump.
Filter.
Maybe the IP is going. Got any fuel puddles underneath it?
Click to expand...

Lift pump was new last year. The local Chevy dealership even installed it since it was stranded in a snow storm and I needed it back asap to plow with. It has been running better than ever 'til now. Have not seen or smelled any fuel. I should mention that it was raining like the dickens the day it started running poorly. Could that have anything to do with it? Thanks.

Indy4x4Fab said:
check ur oil if the fuel pump is going out it could be filling ur crank case with diesel had it happen to me the same way a week ago. i was almost a full quart over full.
Click to expand...

I did check the oil just to make sure it had some but I will check again to see if it smells like diesel fuel. Thanks.
 
6.2Blazer said:
How recently did you fuel up before the problem started? I've been on a roadtrip and got a bad tank of fuel and it started running pretty bad within a short distance. Changing the fuel filter and a fresh tank of fuel got it back to normal.
Click to expand...

Fueled up the week before. Went over 75 miles on the tank before it was having issues. Sounds like I should definitely change the filter. Been a little wary of it because the dealership told me those things tend to develop air leaks. Kind of going with the philosophy of "If it ain't broke, don't fix it." And the M1009 is the most neglected rig in the fleet. Looks like things have changed.
 
Could be the filter base has cracked and letting in air. The square type filter bases are prone to crack and let air in.....Like others have said, filter, lift pump, or IP going out. I just had IP rebuilt for 400. Also replaced my mechanical lift pump with an electric so its not such a pain in the butt on filter changes or if I run out of fuel.
 
KevinL said:
Remove the return fitting on top of the injection pump and check for coffee grounds in it
Click to expand...

Uhh, ok, what... Could use some clarification here.

k20 said:
Could be the filter base has cracked and letting in air. The square type filter bases are prone to crack and let air in.....Like others have said, filter, lift pump, or IP going out. I just had IP rebuilt for 400. Also replaced my mechanical lift pump with an electric so its not such a pain in the butt on filter changes or if I run out of fuel.
Click to expand...

Should have a chance to replace the filter today. It has the square type filter base. Is there any other steps to doing this or is it just plug and play? Do you have any info on the electric lift pump like part numbers, where you got the part, and how it is working so far?
 
The lift pump replacement thread stickied in the diesel section has an excellent write up on how to bleed any air out of your system. It was damn easy using those instructions.

Go get a can of diesel kleen or something. I filled my filter with it and then did the swap.
 
CUCV2 said:
Never. Probably should replace that regardless. Thanks.



Lift pump was new last year. The local Chevy dealership even installed it since it was stranded in a snow storm and I needed it back asap to plow with. It has been running better than ever 'til now. Have not seen or smelled any fuel. I should mention that it was raining like the dickens the day it started running poorly. Could that have anything to do with it? Thanks.



I did check the oil just to make sure it had some but I will check again to see if it smells like diesel fuel. Thanks.
Click to expand...


Has the truck been driven much before you took this "long" trip?....reason I ask,is you say it started after a drive in rainy weather---if the fuel filler pipe going to the tank has rusted thru,as they often do,water spraying off the tires will find its way into the gas tank---I took a truck in to do an electric fuel pump replacement one day,and the tank was 3/4 full--only trouble was the owner said he had driven it a lot farther than he usually could on a full tank,before it started dying out and running very sluggishly...when I pulled the tank out and removed the fuel pump,it had a good 5 gallons of water in the gas!--plus a lot of dead leaves,sand,and other crud that got tossed into the hole in the filler pipe that had flaked off of it!...

After I replaced the fuel pump & dumped the crappy gas/water & crud mix out of the tank,the truck ran so much better,the guy actually squealed the tires as he pulled away from my driveway--said it had never had that much power since he owned it!...I found a recently replaced fuel filler neck pipe at a junkyard on a similar truck,that was good luck,because new ones are over 100 bucks..I paid 20 for it,still had a GM part sticker on it,looked brand new!...
 
If you have never replaced the fuel filter you definitely need to. That would be my first move in this situation. Also, if you haven't replace the air filter recently you probably should. Back when mine was a daily driver, including living in the country and working construction which subjected it to a lot of dust, I could tell when the filters needed changed by the seat of the pants.
 
AJMBLAZER said:
The lift pump replacement thread stickied in the diesel section has an excellent write up on how to bleed any air out of your system. It was damn easy using those instructions.

Go get a can of diesel kleen or something. I filled my filter with it and then did the swap.
Click to expand...

Fuel filter swap done. Glad it is done as it is a normal maintenance item. Truck still has the same issues though.

diesel4me said:
Has the truck been driven much before you took this "long" trip?....reason I ask,is you say it started after a drive in rainy weather---if the fuel filler pipe going to the tank has rusted thru,as they often do,water spraying off the tires will find its way into the gas tank---I took a truck in to do an electric fuel pump replacement one day,and the tank was 3/4 full--only trouble was the owner said he had driven it a lot farther than he usually could on a full tank,before it started dying out and running very sluggishly...when I pulled the tank out and removed the fuel pump,it had a good 5 gallons of water in the gas!--plus a lot of dead leaves,sand,and other crud that got tossed into the hole in the filler pipe that had flaked off of it!...

After I replaced the fuel pump & dumped the crappy gas/water & crud mix out of the tank,the truck ran so much better,the guy actually squealed the tires as he pulled away from my driveway--said it had never had that much power since he owned it!...I found a recently replaced fuel filler neck pipe at a junkyard on a similar truck,that was good luck,because new ones are over 100 bucks..I paid 20 for it,still had a GM part sticker on it,looked brand new!...
Click to expand...

Good idea. I checked the filler neck and it looks solid. The truck started running poorly after it was parked for half and hour. Was running fine before that.

6.2Blazer said:
If you have never replaced the fuel filter you definitely need to. That would be my first move in this situation. Also, if you haven't replace the air filter recently you probably should. Back when mine was a daily driver, including living in the country and working construction which subjected it to a lot of dust, I could tell when the filters needed changed by the seat of the pants.
Click to expand...

Pulled the air cleaner to see if would make a difference. Sounded a little different but still lacked power. Revved the motor up and saw a lot of white smoke. Not sure if this was because it was cold but it was way more than there should be.

The truck just sounds wrong. Not sure if the timing (injector pump) is off somehow or the compression is low but the normal diesel rattle is gone.
 
Sounds like timing. We have a HMMWV at work like that. I keep telling the mechanics it's not supposed to sound like a 350 but they just look at me funny.
 
Its a CUCV, check every single electrical connection in the engine bay and take a file to them and make them shiny, especially the pink wire on top of the IP. I've fixed more weird symptoms than I can count from stupid fixes like bad connections and loose engine components. If its rubber, replace it. Tighten everything down in the engine bay. Rule out all the easy stuff first.
 
I'm interested in finding out what your problem is. I just bought an 85 k20 with the 6.2 and I'm trying to track down my power issues. I got a tip from another user to install some clear tubing in a few spots to investigate if I'm getting air, and from where.

The following link is the results.

http://s171.photobucket.com/albums/u316/philhart/?action=view&current=2011-04-25_19-25-56_460.mp4

I'm not getting leaks (besides the filter housing) so there must be some air coming from either the Lift Pump or the tank itself. Sounds like I need to check my filler pipe.....
 
White smoke can also indicate a leaky head gasket, btw!

Unburnt diesel is more of a grey/blue color and has a very harsh smell to it.
 
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