'86 CJ7 Shaking after ignition is turned off

I just bought this Jeep a few weeks ago and it was running just fine.
About a week after I got it, I realized it needed a new carb as the
float was stuck in the current one. I replaced the carb with a rebuilt
one and it was running just fine again. Now, maybe two weeks later,
all of a sudden when I turn the ignition off when I get home, the
engine shuts off then maybe a fraction of a second later it starts
shaking like it wants to start up again (sort of like bucking?). I
have noticed the shaking is directly related to the amount of time I
have been driving for. If I run out for a few minutes, it might not
shake at all when I turn it off. But if I go for a half hour long
drive, when I go to turn it off, the engine starts shaking. Any ideas
what could be going on? Any help at all would be greatly appreciated!
I have a 1986 CJ7 73K, 5 speed manual with an inline 6. Thanks, Jason

It's dieseling, because the idle is too high. Usually the choke
fast idle cam linkage is sticking. And of course that cheap gasoline you
trying to wean it on.
God Bless America, Bill O|||||||O
http://www.billhughes.com/

Jay wrote:
>
> I just bought this Jeep a few weeks ago and it was running just fine.
> About a week after I got it, I realized it needed a new carb as the
> float was stuck in the current one. I replaced the carb with a rebuilt
> one and it was running just fine again. Now, maybe two weeks later,
> all of a sudden when I turn the ignition off when I get home, the
> engine shuts off then maybe a fraction of a second later it starts
> shaking like it wants to start up again (sort of like bucking?). I
> have noticed the shaking is directly related to the amount of time I
> have been driving for. If I run out for a few minutes, it might not
> shake at all when I turn it off. But if I go for a half hour long
> drive, when I go to turn it off, the engine starts shaking. Any ideas
> what could be going on? Any help at all would be greatly appreciated!
> I have a 1986 CJ7 73K, 5 speed manual with an inline 6. Thanks, Jason

Bill,

Cheapass gasoline causes pinging under load, not dieseling.

Earle

"L.W.(Bill) Hughes III" > wrote in message
...
> It's dieseling, because the idle is too high. Usually the choke
> fast idle cam linkage is sticking. And of course that cheap gasoline you
> trying to wean it on.
> God Bless America, Bill O|||||||O
> http://www.billhughes.com/
>
> Jay wrote:
> >
> > I just bought this Jeep a few weeks ago and it was running just fine.
> > About a week after I got it, I realized it needed a new carb as the
> > float was stuck in the current one. I replaced the carb with a rebuilt
> > one and it was running just fine again. Now, maybe two weeks later,
> > all of a sudden when I turn the ignition off when I get home, the
> > engine shuts off then maybe a fraction of a second later it starts
> > shaking like it wants to start up again (sort of like bucking?). I
> > have noticed the shaking is directly related to the amount of time I
> > have been driving for. If I run out for a few minutes, it might not
> > shake at all when I turn it off. But if I go for a half hour long
> > drive, when I go to turn it off, the engine starts shaking. Any ideas
> > what could be going on? Any help at all would be greatly appreciated!
> > I have a 1986 CJ7 73K, 5 speed manual with an inline 6. Thanks, Jason



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Not a fix but this will stop your problem. When you shut the engine off
leave the Jeep in gear and let off the clutch.

When I shut mine down I always leave it in gear and will usually let off
the clutch as I switch the engine off, it's a habit I've had for years
and do it in all my vehicles. It positively shuts the engine off and
with the vehicle in gear there is little chance it's going to roll
either (except in a overdrive equipped Studebaker, but that's more than
a little off topic!).

Jeff DeWitt

Jay wrote:
> I just bought this Jeep a few weeks ago and it was running just fine.
> About a week after I got it, I realized it needed a new carb as the
> float was stuck in the current one. I replaced the carb with a rebuilt
> one and it was running just fine again. Now, maybe two weeks later,
> all of a sudden when I turn the ignition off when I get home, the
> engine shuts off then maybe a fraction of a second later it starts
> shaking like it wants to start up again (sort of like bucking?). I
> have noticed the shaking is directly related to the amount of time I
> have been driving for. If I run out for a few minutes, it might not
> shake at all when I turn it off. But if I go for a half hour long
> drive, when I go to turn it off, the engine starts shaking. Any ideas
> what could be going on? Any help at all would be greatly appreciated!
> I have a 1986 CJ7 73K, 5 speed manual with an inline 6. Thanks, Jason
>

We a agree to disagree.
God Bless America, Bill O|||||||O
http://www.billhughes.com/

Earle Horton wrote:
>
> Bill,
>
> Cheapass gasoline causes pinging under load, not dieseling.
>
> Earle

"Dieseling" as yours sounds like it is doing is often caused by a
build-up of carbon inside the combustion chambers. The carbon continues
to glow after the last combustion stroke which propels the engine in
another rotation again, which with a mechanical fuel pump keeps the fuel
going. Then the glowing carbon re-ignites the fuel mixture in place of
the spark plug again.

The cure, if this is the problem and it sounds like it is, is to get rid
of the carbon build-up. The easiest way to do this is to slowly (!!)
feed 12-16 ounces of plain water into the air intake as the engine is
running, keeping the RPMs up slightly. NO, this will NOT cause
hydrolock providing you feed the water in slowly and in a controlled
manner over a minute to two minutes. Just slowly trickle it and
maintain control over the water so you don't dump it in too quickly by
accident.

The water will scavenge the carbon deposits and though it may take more
than one treatment, this will leave the combustion chambers clean as a
whistle. No I didn't just make this up, this technique has been used at
least from the thirties or forties to get rid of carbon. The water
creates mini shock-waves that act to break the carbon up so it can be
ejected through the exhaust system.

Try it.

Jerry

Jay wrote:
> I just bought this Jeep a few weeks ago and it was running just fine.
> About a week after I got it, I realized it needed a new carb as the
> float was stuck in the current one. I replaced the carb with a rebuilt
> one and it was running just fine again. Now, maybe two weeks later,
> all of a sudden when I turn the ignition off when I get home, the
> engine shuts off then maybe a fraction of a second later it starts
> shaking like it wants to start up again (sort of like bucking?). I
> have noticed the shaking is directly related to the amount of time I
> have been driving for. If I run out for a few minutes, it might not
> shake at all when I turn it off. But if I go for a half hour long
> drive, when I go to turn it off, the engine starts shaking. Any ideas
> what could be going on? Any help at all would be greatly appreciated!
> I have a 1986 CJ7 73K, 5 speed manual with an inline 6. Thanks, Jason
>

--
Jerry Bransford
PP-ASEL N6TAY
See the Geezer Jeep at
http://members.cox.net/jerrypb/

Would a spray-bottle work better than pouring it in? I have one I use to
check for bad plug wires. Mist under the hood at night and look for the
light-show.


"Jerry Bransford" > wrote in message
news:juwdg.1012$sP1.459@fed1read07...

> The cure, if this is the problem and it sounds like it is, is to get rid
> of the carbon build-up. The easiest way to do this is to slowly (!!)
> feed 12-16 ounces of plain water into the air intake as the engine is
> running, keeping the RPMs up slightly. NO, this will NOT cause
> hydrolock providing you feed the water in slowly and in a controlled
> manner over a minute to two minutes. Just slowly trickle it and
> maintain control over the water so you don't dump it in too quickly by
> accident.

No you need a steady slow stream of 'water' to shock the carbon off.

I have had excellent results using a pint of ATF instead of water to do
this. The ATF makes a massive cloud of smoke though. I have heard from
enough people about the water instead that I will use that next time and
see how it goes.

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)

Steve Foley wrote:
>
> Would a spray-bottle work better than pouring it in? I have one I use to
> check for bad plug wires. Mist under the hood at night and look for the
> light-show.
>
> "Jerry Bransford" > wrote in message
> news:juwdg.1012$sP1.459@fed1read07...
>
> > The cure, if this is the problem and it sounds like it is, is to get rid
> > of the carbon build-up. The easiest way to do this is to slowly (!!)
> > feed 12-16 ounces of plain water into the air intake as the engine is
> > running, keeping the RPMs up slightly. NO, this will NOT cause
> > hydrolock providing you feed the water in slowly and in a controlled
> > manner over a minute to two minutes. Just slowly trickle it and
> > maintain control over the water so you don't dump it in too quickly by
> > accident.

Just so you know, the float needles stick all the time with today's
'fuel'. A tap with a piece of 2x4 or a rubber mallet can fix them
sometimes, but you also can just pull the needle and seat out from the
front of the carb and clean the needle's 3 wings and the slide area. I
need to do mine once a year usually.

A carb kit comes with a new needle and seat and the kit costs about
$25.00 and is easy to put in....

The after running can be caused by too high an idle or more likely
carbon buildup. There are comments earlier in the thread about the
carbon and how to get rid of it.

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)

Jay wrote:
>
> I just bought this Jeep a few weeks ago and it was running just fine.
> About a week after I got it, I realized it needed a new carb as the
> float was stuck in the current one. I replaced the carb with a rebuilt
> one and it was running just fine again. Now, maybe two weeks later,
> all of a sudden when I turn the ignition off when I get home, the
> engine shuts off then maybe a fraction of a second later it starts
> shaking like it wants to start up again (sort of like bucking?). I
> have noticed the shaking is directly related to the amount of time I
> have been driving for. If I run out for a few minutes, it might not
> shake at all when I turn it off. But if I go for a half hour long
> drive, when I go to turn it off, the engine starts shaking. Any ideas
> what could be going on? Any help at all would be greatly appreciated!
> I have a 1986 CJ7 73K, 5 speed manual with an inline 6. Thanks, Jason

If you live in the "rust belt", ATF is good for clearing mosquitoes out of
your neighborhood. ;^)

Try properly adjusting the idle speed and mixture properly, before doing
anything like this. A rebuilt carburetor does not come from the rebuilder
with these set up for you.

Earle

"Mike Romain" > wrote in message
...
> No you need a steady slow stream of 'water' to shock the carbon off.
>
> I have had excellent results using a pint of ATF instead of water to do
> this. The ATF makes a massive cloud of smoke though. I have heard from
> enough people about the water instead that I will use that next time and
> see how it goes.
>
> 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)
>
> Steve Foley wrote:
> >
> > Would a spray-bottle work better than pouring it in? I have one I use to
> > check for bad plug wires. Mist under the hood at night and look for the
> > light-show.
> >
> > "Jerry Bransford" > wrote in message
> > news:juwdg.1012$sP1.459@fed1read07...
> >
> > > The cure, if this is the problem and it sounds like it is, is to get
rid
> > > of the carbon build-up. The easiest way to do this is to slowly (!!)
> > > feed 12-16 ounces of plain water into the air intake as the engine is
> > > running, keeping the RPMs up slightly. NO, this will NOT cause
> > > hydrolock providing you feed the water in slowly and in a controlled
> > > manner over a minute to two minutes. Just slowly trickle it and
> > > maintain control over the water so you don't dump it in too quickly by
> > > accident.



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