If the idle mix screws haven't been messed with recently, they are not
the issue. I would touch them only as a last resort. There are two of
them in the front of the base plate.

You are far more likely to have a loose manifold or a carboned up EGR
valve. The carb itself is known to come loose at the base plate too!

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

"lynnhowlyn@aol.com" wrote:
>
> Nope - no puking of oil into the air cleaner.
> I'll do the various leak checks that several of you have suggested.
> Not sure if there's any "plastic caps" left anywhere on the carb that
> may be hiding mixture adjusting screws. Approx where on the carb will
> they be located?
>
> Lots of great advice - even from the couple old guys (says Lynn with
> the full head of white hair!!)
>
> Thanks!
>
> Earle Horton wrote:
> > "Hootowl" <ELN/zooo@earthlink.net> wrote in message
> > news:21vu82l7jci6u3bos7mp5o69icghn1vc5l@4ax.com...
> > > On Tue, 13 Jun 2006 08:42:40 -0600, "Earle Horton"
> > > <earle-NOSPAM-horton@msn.com> wrote:
> > >
> > > >The most common cause for backfiring on deceleration is idle mixture too
> > > >lean. That could be a vacuum leak with this vintage. They really do
> > > >have too many vacuum lines, don't they? If that is not it, then short
> > > >of a new or rebuilt carburetor, I don't know how you get a proper
> > > >idle mixture. With older models you simply back off the idle mixture
> > > >screw, until the engine is getting a rich enough mixture. With the smog
> > > >controlled models, there is
> > > >usually something to prevent that.
> > >
> > > Plastic caps that are easily removed with a pocket/exacto knife or the
> > > tip of a soldering iron (both are standard shop practices).
> > >
> > Quite. If you are going to do that, it is a good idea to record the number
> > of turns out for the factory setting. Just in case you later decide, that
> > the problem was something else.
> >
> > Earle

 

On 13 Jun 2006 21:30:25 -0700, "lynnhowlyn@aol.com"
<lynnhowlyn@aol.com> wrote:

>Nope - no puking of oil into the air cleaner.
>I'll do the various leak checks that several of you have suggested.
>Not sure if there's any "plastic caps" left anywhere on the carb that
>may be hiding mixture adjusting screws. Approx where on the carb will
>they be located?

On the "main body", just behind the primary bowl on a 4-barrerl carb
(I don't remember what engine you said you have-if a V8, It will
almost certainly be a 4-bbl). About the same place on a 2-barrel,
IIRC. A dealer of parts house can tell you.

Dan
>
>Lots of great advice - even from the couple old guys (says Lynn with
>the full head of white hair!!)
>
>Thanks!
>
>
>Earle Horton wrote:
>> "Hootowl" <ELN/zooo@earthlink.net> wrote in message
>> news:21vu82l7jci6u3bos7mp5o69icghn1vc5l@4ax.com...
>> > On Tue, 13 Jun 2006 08:42:40 -0600, "Earle Horton"
>> > <earle-NOSPAM-horton@msn.com> wrote:
>> >
>> > >The most common cause for backfiring on deceleration is idle mixture too
>> > >lean. That could be a vacuum leak with this vintage. They really do
>> > >have too many vacuum lines, don't they? If that is not it, then short
>> > >of a new or rebuilt carburetor, I don't know how you get a proper
>> > >idle mixture. With older models you simply back off the idle mixture
>> > >screw, until the engine is getting a rich enough mixture. With the smog
>> > >controlled models, there is
>> > >usually something to prevent that.
>> >
>> > Plastic caps that are easily removed with a pocket/exacto knife or the
>> > tip of a soldering iron (both are standard shop practices).
>> >
>> Quite. If you are going to do that, it is a good idea to record the number
>> of turns out for the factory setting. Just in case you later decide, that
>> the problem was something else.
>>
>> Earle

 

On 13 Jun 2006 21:30:25 -0700, "lynnhowlyn@aol.com"
<lynnhowlyn@aol.com> wrote:

>Nope - no puking of oil into the air cleaner.
>I'll do the various leak checks that several of you have suggested.
>Not sure if there's any "plastic caps" left anywhere on the carb that
>may be hiding mixture adjusting screws. Approx where on the carb will
>they be located?

On the "main body", just behind the primary bowl on a 4-barrerl carb
(I don't remember what engine you said you have-if a V8, It will
almost certainly be a 4-bbl). About the same place on a 2-barrel,
IIRC. A dealer of parts house can tell you.

Dan
>
>Lots of great advice - even from the couple old guys (says Lynn with
>the full head of white hair!!)
>
>Thanks!
>
>
>Earle Horton wrote:
>> "Hootowl" <ELN/zooo@earthlink.net> wrote in message
>> news:21vu82l7jci6u3bos7mp5o69icghn1vc5l@4ax.com...
>> > On Tue, 13 Jun 2006 08:42:40 -0600, "Earle Horton"
>> > <earle-NOSPAM-horton@msn.com> wrote:
>> >
>> > >The most common cause for backfiring on deceleration is idle mixture too
>> > >lean. That could be a vacuum leak with this vintage. They really do
>> > >have too many vacuum lines, don't they? If that is not it, then short
>> > >of a new or rebuilt carburetor, I don't know how you get a proper
>> > >idle mixture. With older models you simply back off the idle mixture
>> > >screw, until the engine is getting a rich enough mixture. With the smog
>> > >controlled models, there is
>> > >usually something to prevent that.
>> >
>> > Plastic caps that are easily removed with a pocket/exacto knife or the
>> > tip of a soldering iron (both are standard shop practices).
>> >
>> Quite. If you are going to do that, it is a good idea to record the number
>> of turns out for the factory setting. Just in case you later decide, that
>> the problem was something else.
>>
>> Earle

 

On 13 Jun 2006 21:30:25 -0700, "lynnhowlyn@aol.com"
<lynnhowlyn@aol.com> wrote:

>Nope - no puking of oil into the air cleaner.
>I'll do the various leak checks that several of you have suggested.
>Not sure if there's any "plastic caps" left anywhere on the carb that
>may be hiding mixture adjusting screws. Approx where on the carb will
>they be located?

On the "main body", just behind the primary bowl on a 4-barrerl carb
(I don't remember what engine you said you have-if a V8, It will
almost certainly be a 4-bbl). About the same place on a 2-barrel,
IIRC. A dealer of parts house can tell you.

Dan
>
>Lots of great advice - even from the couple old guys (says Lynn with
>the full head of white hair!!)
>
>Thanks!
>
>
>Earle Horton wrote:
>> "Hootowl" <ELN/zooo@earthlink.net> wrote in message
>> news:21vu82l7jci6u3bos7mp5o69icghn1vc5l@4ax.com...
>> > On Tue, 13 Jun 2006 08:42:40 -0600, "Earle Horton"
>> > <earle-NOSPAM-horton@msn.com> wrote:
>> >
>> > >The most common cause for backfiring on deceleration is idle mixture too
>> > >lean. That could be a vacuum leak with this vintage. They really do
>> > >have too many vacuum lines, don't they? If that is not it, then short
>> > >of a new or rebuilt carburetor, I don't know how you get a proper
>> > >idle mixture. With older models you simply back off the idle mixture
>> > >screw, until the engine is getting a rich enough mixture. With the smog
>> > >controlled models, there is
>> > >usually something to prevent that.
>> >
>> > Plastic caps that are easily removed with a pocket/exacto knife or the
>> > tip of a soldering iron (both are standard shop practices).
>> >
>> Quite. If you are going to do that, it is a good idea to record the number
>> of turns out for the factory setting. Just in case you later decide, that
>> the problem was something else.
>>
>> Earle