repeated muffled backfire???
 

I have an 84 cj-7 and i dont know a lot about them... but i've done
pretty well restoring it from its previous condition of scarecrow in a
field.. anyways i have replaced the carb/spark plugs/spark plug wires/
fuel filter/ air filter... but i have a continuous muffled backfire...
however when adjusting the timing while trying to fix this i noticed
that it goes away when i block the green tube that goes from the carb
to the vassum control(i think...its on the side of the distributor)
anyways when i block that the backfire stops...when i unblock it the
backfire starts again... if anyone has any suggestion please let me
know... Thanks....



~Dan

Re: repeated muffled backfire???
 

Danny did pass the time by typing:
> I have an 84 cj-7 and i dont know a lot about them... but i've done
> pretty well restoring it from its previous condition of scarecrow in a
> field.. anyways i have replaced the carb/spark plugs/spark plug wires/
> fuel filter/ air filter... but i have a continuous muffled backfire...
> however when adjusting the timing while trying to fix this i noticed
> that it goes away when i block the green tube that goes from the carb
> to the vassum control(i think...its on the side of the distributor)
> anyways when i block that the backfire stops...when i unblock it the
> backfire starts again... if anyone has any suggestion please let me
> know... Thanks....

That tube is your vacuum advance. Your timing is hosed.
Time to start checking for cracked lines and
if the vacuum pot has failed.
This is for a Jag, but the concept is the same.
http://neptune.spacebears.com/cars/stories/vacadv.html

A few more things to read
http://www.jedi.com/obiwan/jeep/misc/vacuumhoses.html

85 but should be the same.
http://autorepair.about.com/library/bl252lib.htm


--
DougW

Re: repeated muffled backfire???
 

Danny did pass the time by typing:
> I have an 84 cj-7 and i dont know a lot about them... but i've done
> pretty well restoring it from its previous condition of scarecrow in a
> field.. anyways i have replaced the carb/spark plugs/spark plug wires/
> fuel filter/ air filter... but i have a continuous muffled backfire...
> however when adjusting the timing while trying to fix this i noticed
> that it goes away when i block the green tube that goes from the carb
> to the vassum control(i think...its on the side of the distributor)
> anyways when i block that the backfire stops...when i unblock it the
> backfire starts again... if anyone has any suggestion please let me
> know... Thanks....

That tube is your vacuum advance. Your timing is hosed.
Time to start checking for cracked lines and
if the vacuum pot has failed.
This is for a Jag, but the concept is the same.
http://neptune.spacebears.com/cars/stories/vacadv.html

A few more things to read
http://www.jedi.com/obiwan/jeep/misc/vacuumhoses.html

85 but should be the same.
http://autorepair.about.com/library/bl252lib.htm


--
DougW

Re: repeated muffled backfire???
 

Danny did pass the time by typing:
> I have an 84 cj-7 and i dont know a lot about them... but i've done
> pretty well restoring it from its previous condition of scarecrow in a
> field.. anyways i have replaced the carb/spark plugs/spark plug wires/
> fuel filter/ air filter... but i have a continuous muffled backfire...
> however when adjusting the timing while trying to fix this i noticed
> that it goes away when i block the green tube that goes from the carb
> to the vassum control(i think...its on the side of the distributor)
> anyways when i block that the backfire stops...when i unblock it the
> backfire starts again... if anyone has any suggestion please let me
> know... Thanks....

That tube is your vacuum advance. Your timing is hosed.
Time to start checking for cracked lines and
if the vacuum pot has failed.
This is for a Jag, but the concept is the same.
http://neptune.spacebears.com/cars/stories/vacadv.html

A few more things to read
http://www.jedi.com/obiwan/jeep/misc/vacuumhoses.html

85 but should be the same.
http://autorepair.about.com/library/bl252lib.htm


--
DougW

Re: repeated muffled backfire???
 

On 25 Jun 2006 18:53:24 -0700, "Danny" <Carnley588@yahoo.com> wrote:

>I have an 84 cj-7 and i dont know a lot about them... but i've done
>pretty well restoring it from its previous condition of scarecrow in a
>field.. anyways i have replaced the carb/spark plugs/spark plug wires/
>fuel filter/ air filter... but i have a continuous muffled backfire...
>however when adjusting the timing while trying to fix this i noticed
>that it goes away when i block the green tube that goes from the carb
>to the vassum control(i think...its on the side of the distributor)
>anyways when i block that the backfire stops...when i unblock it the
>backfire starts again... if anyone has any suggestion please let me
>know... Thanks....

Dan,

That is the vacuum advance solenoid, and it sounds like the diaphragm
inside may be leaking. Take the other end of the line off the carb,
and suck on it. If you get any air through it at all, that's it,
simple and cheap. Also check the line itself for a hole or dry rot.

Dan
>
>
>
> ~Dan

Re: repeated muffled backfire???
 

On 25 Jun 2006 18:53:24 -0700, "Danny" <Carnley588@yahoo.com> wrote:

>I have an 84 cj-7 and i dont know a lot about them... but i've done
>pretty well restoring it from its previous condition of scarecrow in a
>field.. anyways i have replaced the carb/spark plugs/spark plug wires/
>fuel filter/ air filter... but i have a continuous muffled backfire...
>however when adjusting the timing while trying to fix this i noticed
>that it goes away when i block the green tube that goes from the carb
>to the vassum control(i think...its on the side of the distributor)
>anyways when i block that the backfire stops...when i unblock it the
>backfire starts again... if anyone has any suggestion please let me
>know... Thanks....

Dan,

That is the vacuum advance solenoid, and it sounds like the diaphragm
inside may be leaking. Take the other end of the line off the carb,
and suck on it. If you get any air through it at all, that's it,
simple and cheap. Also check the line itself for a hole or dry rot.

Dan
>
>
>
> ~Dan

Re: repeated muffled backfire???
 

On 25 Jun 2006 18:53:24 -0700, "Danny" <Carnley588@yahoo.com> wrote:

>I have an 84 cj-7 and i dont know a lot about them... but i've done
>pretty well restoring it from its previous condition of scarecrow in a
>field.. anyways i have replaced the carb/spark plugs/spark plug wires/
>fuel filter/ air filter... but i have a continuous muffled backfire...
>however when adjusting the timing while trying to fix this i noticed
>that it goes away when i block the green tube that goes from the carb
>to the vassum control(i think...its on the side of the distributor)
>anyways when i block that the backfire stops...when i unblock it the
>backfire starts again... if anyone has any suggestion please let me
>know... Thanks....

Dan,

That is the vacuum advance solenoid, and it sounds like the diaphragm
inside may be leaking. Take the other end of the line off the carb,
and suck on it. If you get any air through it at all, that's it,
simple and cheap. Also check the line itself for a hole or dry rot.

Dan
>
>
>
> ~Dan

Re: repeated muffled backfire???
 

Ouch.... That engine's timing is also controlled by a computer....

Do you still have the emissions computer running things?

But anyway, the timing is also vacuum and mechanically controlled. That
line is the vacuum advance. You should be able to take the line off the
carb and suck on it and it should hold vacuum.

Inside the distributor is a base plate that needs to be lubricated. The
oil pad for it is under the rotor. You pull the rotor off and oil the
center of the shaft with 10W30 oil, then work the plate.

You should be able to grab the rotor and turn it. It should be heavily
spring loaded and spring back into place fast when you let go.

If you suck on that vacuum line when the distributor cap is open, you
also should see the base plate move or at least you should be able to
move the vacuum advance linkage with your fingers.

Check that stuff out and get back to us. There are more things to
'play' with, but the 'basics' need to work first.

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)

Danny wrote:
>
> I have an 84 cj-7 and i dont know a lot about them... but i've done
> pretty well restoring it from its previous condition of scarecrow in a
> field.. anyways i have replaced the carb/spark plugs/spark plug wires/
> fuel filter/ air filter... but i have a continuous muffled backfire...
> however when adjusting the timing while trying to fix this i noticed
> that it goes away when i block the green tube that goes from the carb
> to the vassum control(i think...its on the side of the distributor)
> anyways when i block that the backfire stops...when i unblock it the
> backfire starts again... if anyone has any suggestion please let me
> know... Thanks....
>
> ~Dan

Re: repeated muffled backfire???
 

Ouch.... That engine's timing is also controlled by a computer....

Do you still have the emissions computer running things?

But anyway, the timing is also vacuum and mechanically controlled. That
line is the vacuum advance. You should be able to take the line off the
carb and suck on it and it should hold vacuum.

Inside the distributor is a base plate that needs to be lubricated. The
oil pad for it is under the rotor. You pull the rotor off and oil the
center of the shaft with 10W30 oil, then work the plate.

You should be able to grab the rotor and turn it. It should be heavily
spring loaded and spring back into place fast when you let go.

If you suck on that vacuum line when the distributor cap is open, you
also should see the base plate move or at least you should be able to
move the vacuum advance linkage with your fingers.

Check that stuff out and get back to us. There are more things to
'play' with, but the 'basics' need to work first.

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)

Danny wrote:
>
> I have an 84 cj-7 and i dont know a lot about them... but i've done
> pretty well restoring it from its previous condition of scarecrow in a
> field.. anyways i have replaced the carb/spark plugs/spark plug wires/
> fuel filter/ air filter... but i have a continuous muffled backfire...
> however when adjusting the timing while trying to fix this i noticed
> that it goes away when i block the green tube that goes from the carb
> to the vassum control(i think...its on the side of the distributor)
> anyways when i block that the backfire stops...when i unblock it the
> backfire starts again... if anyone has any suggestion please let me
> know... Thanks....
>
> ~Dan

Re: repeated muffled backfire???
 

Ouch.... That engine's timing is also controlled by a computer....

Do you still have the emissions computer running things?

But anyway, the timing is also vacuum and mechanically controlled. That
line is the vacuum advance. You should be able to take the line off the
carb and suck on it and it should hold vacuum.

Inside the distributor is a base plate that needs to be lubricated. The
oil pad for it is under the rotor. You pull the rotor off and oil the
center of the shaft with 10W30 oil, then work the plate.

You should be able to grab the rotor and turn it. It should be heavily
spring loaded and spring back into place fast when you let go.

If you suck on that vacuum line when the distributor cap is open, you
also should see the base plate move or at least you should be able to
move the vacuum advance linkage with your fingers.

Check that stuff out and get back to us. There are more things to
'play' with, but the 'basics' need to work first.

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)

Danny wrote:
>
> I have an 84 cj-7 and i dont know a lot about them... but i've done
> pretty well restoring it from its previous condition of scarecrow in a
> field.. anyways i have replaced the carb/spark plugs/spark plug wires/
> fuel filter/ air filter... but i have a continuous muffled backfire...
> however when adjusting the timing while trying to fix this i noticed
> that it goes away when i block the green tube that goes from the carb
> to the vassum control(i think...its on the side of the distributor)
> anyways when i block that the backfire stops...when i unblock it the
> backfire starts again... if anyone has any suggestion please let me
> know... Thanks....
>
> ~Dan