From: chance wolf (chance_wolf@shaw.ca)
Date: Mon Dec 13 2004 - 22:56:31 PST
----- Original Message -----
From: "Caleb Pal - MilVeh" <m1009@defcon-3.net>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Monday, December 13, 2004 9:48 PM
Subject: [MV] CUCV Won't start!!! :(
> This morning I went out, and went to start it. It did the
> crank, catch, then crank some more, and then catch about 8-12 times then
> fired off in a cloud of smoke. I went to work, went home for lunch, same
> thing, maybe a bit worse after sitting at work for 4 hrs. At lunch I went
to
> head back, and it fired off ok after lunch after sitting for an hour.
After
> work, fired it up, again hard to start, and a nice cloud of smoke when it
> fired off.
The top of your injector pump is held on by three screws. On that injector
pump top are mounted two solenoids. The one with the larger plug is the
shutoff solenoid for the pump which, so long as 12V is applied, will stay
open and permit fuel flow. The coils like to cook on them after awhile and
will at first be irritatingly intermittent, and then fail altogether. If
that one's failed I wouldn't expect any smoke from the tailpipe though,
white or otherwise, so lets move on to Solenoid No. 2
This one is the Cold Advance Solenoid. At the radiator-end of your injector
pump you'll notice a small fitting with a 3/8 or 5/16 hose attached to the
end of it. That fitting contains a small glass ball on a spring which is
supposed to be opened by the Cold Advance Solenoid mounted in the top of the
pump. When this system is pooched it's incredibly annoying because a bunch
of different crap can happen depending on what's actually failed, but mostly
you have starting problems from cold, and/or lack of power at road speed.
Unscrew the fitting from the top of the injector pump and disconnect it from
the hose. Find yourself a small pin or something and try and work the
little ball and spring up and down via one of the ends of the fitting and
try blow through the other end at the same time. The movement of the ball
as you push against the spring should allow you to blow through it or not
blow much at all depending on the amount you're pressing on the ball. If
it's all gummed up, clean it out with something like carb cleaner or WD40
and play with it again. If you're getting a bunch of little black particles
out of it when you blow through it - uhhh - your injector pump is probably
on the way out (see Note below.) If the little valve works satisfactorily,
apply 12V to the solenoid's trigger (making sure the top of the pump is
grounded if you've removed the pump top to look inside) and observe the
action of the solenoid itself. I've had them go too, but not half as often
as the valve assembly we just cleaned out or the main shutoff solenoid.
From what I've seen, if that little valve isn't open when you start from
cold - you're not going anywhere.
Here's the NOTE part. GM had a problem with those injector pumps on the
CUCVs and civvy models both due to the unexpected action of certain common
diesel additives which were additive'd after the pump was designed. I think
the part itself inside the injector pump is called the Governor Weight
Retainer Clip or something similar, but what happens is this little
composite-material clip slowly dissolves over time thanks to the additives
in modern diesel, and the little black specks'n'particles and junk wind up
in the Cold Advance Valve. When that valve partially plugs or jams partway
closed you get hard starting and puzzling/alarming lack of accelerator
response when you need it most. You can replace the valve with one from the
dealer or from a scrap pump or just keep rodding out the one you have, but
eventually you'll get sick of stopping 3/4 the way up mountain passes in the
pouring rain messing with it, and will get around to changing the injector
pump (or you'll drill an old valve completely out so you can blow through it
all the time, and keep it in the toolbox for emergencies!) Rebuilt pumps
have a new design part which doesn't dissolve.
Also, I'm not a diesel expert, but when I was having problems with mine
along the lines of yours and had done all the stuff I just talked about, the
diesel rebuilders told me that the my injector pump was probably on its last
legs, as the hard-starting thing on a 6.2 with all the subsystems working
usually means you got your money's worth out of it. Everybody without
exception who's changed their injector pump out for a rebuilt one among
those I've talked to wish they'd done it when they first bought the vehicle.
Same with mine. World of difference.
(Also, check to see your glow plugs are actually getting voltage when the
solenoid throws. I've come across a lot which clunk convincingly but don't
pass any current. Yeahswell. :(
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