QuestionQUESTION: Dear Van, I have a problem with my CUCV M1008
I purchased it a month ago with only 7,730 miles, and have since put on 200 miles on it
until it decided to die on me. It started loosing power (with the gas peddle to the floor
It only idled) and stalled, I restarted it and it ran find till I got to my destination which
was only ½ a mile from where it first stalled. 3 hours later I jumped into my truck and
drove for another ½ miles before it started acting up again, restarted it and again drove
½ a mile till it really died and had to be towed home.
The first thing I did to trouble shoot it was remove and replace the fuel filter. I bleed
It till fuel continuously flowed out of the little nipple on the top of the fuel filter housing,
then cracked each fuel injector till there was no air coming out of the injector tubes staring
at the rear of each bank, but it still wouldn’t start.
The next thing I did was replace the air filter, and still no luck. (I had an experience with
a 6.2 diesel in my boat where the exhaust manifold had blown a gasket and the air filter
got clogged with carbon, then the motor would only idle till it stalled, but this wasn’t
the case this time)
3rd thing I tried, was checking on the O-ring behind the senor with in the fuel filter housing.
The O-ring was fine, but I changed it out anyhow, and went trough the whole fuel bleeding
process again, but it still wouldn’t start up
4th on the list that I tried was changing out the temp sensor, with still no luck.
5th was the check valve on the return fuel line on top of the injector jump, no luck.
These are the symptoms that I am experiencing: After the “wait light” on the dash goes off,
I would turn the ignition and the motor seem to fire up for about 2 seconds, then just cranks.
The motor wont start, it has a full tank of fuel. I even cut open the old fuel filter just to see if
There was any contaminants, but it was clean with no water or algae.
Surely hope that you can point me in the right direction, and thank you very much for your time!
P.S. is there any other fuel pump, or fuel filter in the fuel tank?
B. Wild, from Hawaii…
ANSWER: Hi B,
There is no pump in the tank, and only a sock.
I assume you have checked the hose from the filter to the injector pump, to make sure you have a good supply of fuel supplied to the injector pump.
Then on the return line check valve. Try running the engine with that fitting completely removed from the injector pump. I have had those valves get stuck closed, and it advances the timing to where it won't run. The check valve ball in there is transparent, and doesn't even look like there is anything in there. You should be able to blow through that check valve.
Last I can think of right off hand is remove the gas cap, and make sure it isn't sealing and forming a vacuum in the fuel tank.
Keep me informed on this truck, as I like working on them.
I will say, I have had to send almost all of my injector pumps to be rebuilt, but they were running. But the Air Force used jet fuel in them, and it doesn't lubricate as well as diesel.
One other thing that comes to mind.
Check the exhaust system. If it has a bunch of rust or carbon flakes laying inside the muffler, about a half mile of hard running can blow those flakes against the inside openings in the muffler, and plug them up, literally choking the engine. (Kinda like cramming a potato in the tail pipe.) Then, when it dies, or you shut it off, the flakes fall off, and the whole process starts again on the next start.
That can be especially true if the truck has a spark arrester in the tail pipe.
Van
---------- FOLLOW-UP ----------
QUESTION: Dear Van…
I’ve removed the return check valve completely, and the motor will run and it response
when I hit the accelerator. However when I replaced the check valve with another one
from a know running 6.2 it runs for a little while before it begins to loose power and stalls
out again.
When the return fuel line was disconnected, I did not observe any fuel returning from
the fuel injectors, but fuel did splash/shoot out of the injector pump. I tried cleaning
the check valve with brake cleaner, and did observe a free flow from the fuel hose return
end, and a little splatter from the injector side of the check valve.
Do I need to do a bleed down again, after the check valve has been removed, and
re-installed?
What is the timing procedure on a 6.2, M1008 if a was to replace the injector pump?
and do I need any special tools?
P.S. I forgot to list on my previous questions, that I did remove the fuel cap during
earlier testing, and found no changes.
Thank you every much for your speedy reply, and you expertise, B Wild…
AnswerHi B,
I think we are about there.
There is a wire that goes to the passengers side of the injector pump, and a wire that goes to the top of the injector pump.
The one on top operates a solenoid that kills the engine when it is denergized. it is obviously working.
The other wire operates a solenoid inside the pump, when the engine warms up.
That solenoid has a little rod..about the size of a good sized sewing needle, but blunt on the end.
That little rod protrudes up into that little check ball fitting, and actually pushes that little plastic ball off the seat.
For some reason that solenoid isn't working.
The power to it, comes from the temp switch on the fear right edge of the right side head.
It is 12 volts.
Check to see if there is voltage there when the engine is running.
If there isn't, use a jumper wire from the front battery pos, to that solenoid terminal, and see if it makes it run better.
If there is voltage there, but fuel doesn't come out of the fitting on the injector pump front, then that solenoid is not working.
There is a separate ground strap...a tiny one...somewhere there I believe.
You can take the top off the injector pump, and look inside.
I have even run the truck with the cover off. A little messy, but not bad.
But nothing drops loose, and you can see that internal solenoid.
You could even replace that little front check valve fitting with an open fitting. It just wouldn't advance the timing and idle fast when cold.
Let me know if that works.
As for timing the injector pump, there is a little mark on top of the mounting flange of the pump, and a mark on the timing gear housing.
Van
