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6.2 GMC diesel runs rough

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Junkmail717

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Nov 21, 2002, 5:01:46 PM11/21/02
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I have a 83 GMC 6.2 diesel that is running very rough all of a sudden. I just
changed the fuel filters but it didn't change much. It seems to be a fuel
problem. The throttle seems very sensitive it idles rough but will race up
quickly when given more fuel but wants to stall. The motor has under 5000 miles
and most parts were changed including fuel pump. Could someone suggest what my
next step would be. The fuel is clean with new fuel tank.

"Doc"

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Nov 21, 2002, 7:27:32 PM11/21/02
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"Junkmail717" <junkm...@aol.com> wrote in message
news:20021121170146...@mb-cv.aol.com...


Tried turning up the idle on the carb via the idle speed-adjustment screw?
If not, go clockwise 1/2 turn at a time until she's smoothes out.

Doc


Bill 98501

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Nov 21, 2002, 10:42:01 PM11/21/02
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>Tried turning up the idle on the carb via the idle speed-adjustment screw?

So, where exactly is the carb on a 6.2 diesel?

Gary Glaenzer

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Nov 21, 2002, 10:59:28 PM11/21/02
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"Bill 98501" <bill...@aol.com> wrote in message
news:20021121224201...@mb-fl.aol.com...

> >Tried turning up the idle on the carb via the idle speed-adjustment
screw?
>
> So, where exactly is the carb on a 6.2 diesel?

just in front of the distributor, next to the
coil............................


Old Crow

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Nov 21, 2002, 11:02:45 PM11/21/02
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On Fri, 22 Nov 2002 00:27:32 GMT, "\"Doc\"" <som...@nowhere.net>
wrote:

Good trick on a 6.2, Doc. :-)

So, Junk, did they change the injector pump or just the lift pump on
the frame?
--

Old Crow
ASE Master Tech Chevy Master Tech
'82 FLTC 'Pearl'
'84 S-10 4x4 350k miles and still going

"Doc"

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Nov 22, 2002, 12:58:14 AM11/22/02
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"Gary Glaenzer" <nobul...@mchsi.com> wrote in message
news:AYhD9.76148$__1....@rwcrnsc51.ops.asp.att.net...

Next to them thar' squirty things..................the things that shoot gas
into the motor with all the wires.................he he he he he.

Shit, I've been on here for how long now and folks don't know a joke when
they see one......................<sigh>

Doc


Larry

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Nov 22, 2002, 2:07:38 AM11/22/02
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Any codes stored ? If not I would crack the injector lines loose one at
a time while its running. Be careful very high pressure fuel. And see if
you find one that makes no difference in the trucks idle. could be a bad
injector. Or the pump could also be bad. I've changed about a dozen in
the last 10 years

Larry

"Doc"

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Nov 22, 2002, 3:02:43 AM11/22/02
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"Larry" <no...@home.com> wrote in message news:3DDDF2B6...@home.com...

> Any codes stored ? If not I would crack the injector lines loose one at
> a time while its running. Be careful very high pressure fuel. And see if
> you find one that makes no difference in the trucks idle. could be a bad
> injector. Or the pump could also be bad. I've changed about a dozen in
> the last 10 years
>
> Larry

Not too knowledgeable on diesels, but could he use the same <much safer and
less messy> methods used to test gasoline injectors such as:

1) Automotive stethescope <sp?> at each injector to listen for the
tell-tale "clicking" indicating that they're working
2) Resistance check with DMM between the injector terminals
3) Voltage check at FI harness connectors with key set to "ON"
4) Noid light connected to harness connectors while cranking to test for
blinking <verify ECM control of injectors>

Regards,

Doc

Biko

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Nov 22, 2002, 3:33:27 AM11/22/02
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Sorry Doc but on 6.2L diesel, the injectors are mechanical, no electronic,
no code, the injection pump create high pressure, with the indexion of the
pump the right injector open.

I just want to be sure the injection system is really bleed, if not some air
can be trap on the system and the injectors don't have enough pressure to
open. I would try to rebleed each injectors, start the engine and open one
by one each injectors (key 3/4", 1 turn), you can try to rev the engine to
help air to escape.

You can also check if system suck air, to do I change the hose on the top of
the injection pump with a transparent hose. If yes, you will see air
bubbles.

What do you change exactly? Injector pump or just the lift pump.

Biko


""Doc"" <som...@nowhere.net> a écrit dans le message de news:
DwlD9.4854$aM....@newssvr16.news.prodigy.com...

mark

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Nov 22, 2002, 4:19:49 AM11/22/02
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"Gary Glaenzer" <nobul...@mchsi.com> wrote in message news:<AYhD9.76148$__1.4...@rwcrnsc51.ops.asp.att.net>...

Or in the truck being towed out of trouble by the 6.2.....

"Doc"

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Nov 22, 2002, 9:42:57 AM11/22/02
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"mark" <markir...@lycos.co.uk> wrote in message
news:3d03627b.02112...@posting.google.com...

He he he he. Hey, how DO you gap glow plugs anyways? <bg>

Doc


Larry

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Nov 22, 2002, 11:48:56 AM11/22/02
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Doc,
What gives ? Your post reads like I'm giving him bad information "much
safer and less messy". The other way to test diesel injectors is to pull
them all out and use a tester to see at what pressure they open. See the
spray pattern, and see if they drip. I've worked on more 6.2'S than I
care to remember.

Larry

"Doc"

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Nov 22, 2002, 2:19:16 PM11/22/02
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"Larry" <no...@home.com> wrote in message news:3DDE7AE4...@home.com...

> Doc,
> What gives ? Your post reads like I'm giving him bad information "much
> safer and less messy". The other way to test diesel injectors is to pull
> them all out and use a tester to see at what pressure they open. See the
> spray pattern, and see if they drip. I've worked on more 6.2'S than I
> care to remember.
>
> Larry
>

Larry,

Lighten up! I know next to nothing about diesels and the post wasn't
intended as a flame, but rather as a question. Note the wording: "Not too


knowledgeable on diesels, but could he use the same <much safer and less

messy> methods used to test gasoline injectors such as........"

It's difficult to tell via text messages just what tone the author <in this
case me> was using. It was just a question, not intended to make you look
bad or anything, just trying to learn something new. If anyone looks bad
it's me for not even knowing that the injectors on a 6.2 are mechanical and
not electrical! Sorry for the confusion <g>.

Regards,

Doc

Junkmail717

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Nov 22, 2002, 5:33:56 PM11/22/02
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Thank you everyone for your replys. I will give them a try. Right now it seems
to have cleared up, but I think it could happen again.

Biko

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Nov 22, 2002, 6:29:51 PM11/22/02
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If it's gone, it's was probably air in injection system.

You can go on the road and put the foot on the floor a several time. It's
can be enough to let escape the air.

Good luck,

Biko
"Junkmail717" <junkm...@aol.com> a écrit dans le message de news:
20021122173356...@mb-cr.aol.com...

jhultman

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Nov 25, 2002, 3:14:49 PM11/25/02
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Ebay has an item you might be interested.
Its a 6.2 factory manual. covers fuel delivery as well as other
good things. Specific info on parts for various years.
I paid about 60 bucks for the same book, used, via ebay.
It's worth every penny IMO.

If you really want it, bid high. A lot of sniping for these parts...

Jeff H
San Jose, CA.

Also check out www.thedieselpage.com if you have not.
Its' a pay for membership site but the 35 buck annual fee is also
worth it, IMO. Information from gm diesel enthusiasts...

nick leinonen

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Nov 25, 2002, 7:59:27 PM11/25/02
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pump could be mis-timed... air in system [crack fuel lines open at injectors
with lift pump running to bleed] check for air filter restriction. if it has
an egr valve, take a BB and stuff it in the vacuum hose to disable it. it is
useless [now don't flame, gm diesels have mechanical vacuum pumps to make
the vacuum. mounted lower left of engine front]

and it might be as simple as bad fuel. up here in canada, petrocanada diesel
is total $hit. gm diesels run really poor on it..

--


=======================
nick leinonen
nickle...@rogers.com
markham, ontario, canada
http://community.webshots.com/user/nickleinonen
=======================

.


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