Have an '85 M1008 with very sluggish idling and operating issues. Want to learn and figure out how to diagnose and fix it.
CK5
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Who is the 6.2 diesel expert around here?
- Thread starter thatK30guy
- Start date
Installing a new 454 will fix it.
Add boost and fuel.
David
David
red EOD
1/2 ton status
Common problem would be air entering the fuel system. A way to diagnose it would be to plumb a clear hose into the fuel return line coming off the injection pump (easy access and visibility). With the truck running if there's bubbles flowing through the return line then you have a air intrusion issue. Common causes are:
Worn out rubber fuel lines
Hairline cracks in the steel lines
Loose fittings in the fuel delivery plumbing
Truck will start and idle fine until it gets warmed up and then has no power at all. Will continue to idle while trying to rev it up. If I try putting it in gear to move it struggles as it's still idling while trying to rev it up. I've been told it needs a new IP. I already changed out for a new filter but no change. The longer it sits idling and warmed up the more sluggish the motor gets until it shuts off.
red EOD
1/2 ton status
Yea it is a possibility that the IP needs replacement. Before you buy a new injection pump:
1. Install the clear line on the fuel return to check for bubbles. Could be that as things warm up air intrusion happens (had it on a metal line before).
2. Plumb in a fuel pressure gauge either before or after the filter (preferably after the filter). Take note of the initial fuel pressure reading and if it drops as the truck warms up. Won't see much at idle and it can fall to a vacuum at higher RPM with the stock lift pump. Vacuum at idle is a big problem.
3. Run a wire from the battery positive post directly to the fuel shutoff solenoid on the injection pump (pink wire). Of course will need to disconnect this jumper wire to shut down the truck.
3 diagnostic steps that will cut down the possibility of throwing the wrong parts at it.
1st one is checking for air intrusion as stated before.
2nd is testing the fuel pump and potential fuel delivery blockage issues (crap floating in the tank/lines).
3rd tests the electrical from the ignition-injection pump.
This
If you have consistent fuel supply and pressure to the IP, which itself is just a rotary hydraulic pump, then you can isolate your problem to the IP. @red EOD ’s diagnosis steps are spot on.
From there, you may just have a work out IP that can’t build or retain pressure. If you rebuild the IP, try to spring for new injectors at the same time. It’s a small ecosystem of parts.
David
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Are, or aren’t spot on?
Yesn’t
I was going to say he meant are.
Blame it on autocorrect
Now you guys mention the blockage I want to say it feels like that issue because at the initial startup it has no problem waiting for the GP's to heat up and then fire up. The engine will idle fine but with some smoking, of which I forgot to mention, and it will rev up fine also. Just when it gets warm or hot blooded it loses all power. Does sound like a blockage issue as quoted above. I hardly drive the truck and in the seven years I've owned it I haven't put many miles on it at all. Maybe 10K give or take. But I have put in supplement before each winter so not sure if that's affecting anything either.
If it's blockage in the lines is it simply a matter of unhooking at the highest point in the engine bay and blowing compressed air back into the tank? Then needing to drop the tank to clean it out?
What supplements are you using?
I use the green one from power service, it kills fungus which is the biggest problem with ulsd
I'd try a new fuel filter first--one can hold enough fuel to run the engine normally several minutes ,but starve it for fuel after if the element is all dirty and or blocked up with algae if it sat a long time..
A blocked or restricted return line off the injector pump can shut the engine down,I have read about a glass check ball in the fitting on the injector pump that can clog up and cause your kind of issues..
Dirt or old gelled up fuel in the tank can clog the "sock" filter on the fuel line under the sending unit too,and cause fuel starvation --overnight the crud may sink back away from the sock and allow it to start & run normally for awhile till suction from the lift pump pulls it back against it..the lift pump itself may be failing also,checking the fuel pressure is a good idea,though taking off any fuel lines will let air in them and you'll be having fun bleeding the system out to get it to start up again..
Adding an electric fuel pump close to the fuel tank on my 6.2 pickup made a big difference in how it starts and the power level ,I used a Spectra low psi one that puts out 2-5 psi,it makes it a hell of a lot easier to bleed the fuel system too--I run it in addition to the mechanical lift pump ..
A blocked or restricted return line off the injector pump can shut the engine down,I have read about a glass check ball in the fitting on the injector pump that can clog up and cause your kind of issues..
Dirt or old gelled up fuel in the tank can clog the "sock" filter on the fuel line under the sending unit too,and cause fuel starvation --overnight the crud may sink back away from the sock and allow it to start & run normally for awhile till suction from the lift pump pulls it back against it..the lift pump itself may be failing also,checking the fuel pressure is a good idea,though taking off any fuel lines will let air in them and you'll be having fun bleeding the system out to get it to start up again..
Adding an electric fuel pump close to the fuel tank on my 6.2 pickup made a big difference in how it starts and the power level ,I used a Spectra low psi one that puts out 2-5 psi,it makes it a hell of a lot easier to bleed the fuel system too--I run it in addition to the mechanical lift pump ..
Yep.
Tank
Sock screen on pickup
Plumbing
Lift pump
Filter
IP
Injectors
Returns
All these have to move fuel around without blockage or leaks.
I will say the screen in the tank has been known to cause what you describe when it's mostly clogged with junk. Worth checking of the engine bay stuff all seems good.
Tank
Sock screen on pickup
Plumbing
Lift pump
Filter
IP
Injectors
Returns
All these have to move fuel around without blockage or leaks.
I will say the screen in the tank has been known to cause what you describe when it's mostly clogged with junk. Worth checking of the engine bay stuff all seems good.
Can't remember what I had on the shelf but I recently tossed it out since it was old. Don't know why I bought a gallon of the stuff when I don't even drive the truck or rack a lot of miles on it. Should have just gotten a couple ounces of whatever. I feel the supplement may have gone bad or sour over time.
What would be the issue of the smoking at start up and idling? Seems to go away once warmed up.
