machine gun back firing - no power
 

Over the past 7-10 days I have been loosing power with my '83 258 engine to
the point where it is difficult to drive and keep running. It feels like I
am pulling a trailer, and I am getting rapid machine gun style backfiring
through the muffler when I get around 2000 RPM. It has 215,000 miles so it
is a little tired anyways. It felt like the timing had slipped, like
possibly the timing chain had slipped, but when I use a timing light the
mark is still in the ballpark of where it should be, so I don't believe that
is the case. I re-adjusted the timing using only a vacuum gauge to get the
max vacuum and it now idols better, but I still get the machine gun type
back firing when I get over 2000 RPM.



A few months ago I replaced the valve cover from a plastic cover to an
aluminum cover to stop the constant oil leak I was having. In the process I
swapped the valve bridges with the non-bolt style bridge since they were not
needed any longer. When did replace those I torqued them down, and used the
original nuts.



The vacuum advance is still moving properly and has been well cleaned.



Any ideas what is going on? My first idea of timing seems to be more or
less ruled out. I am now leaning towards one of the rocker bolts has come
loose. Any other ideas of what to look for or check?



83 CJ-7

258 I-6 engine

MC2100 carb

stock and original distrubutor

Re: machine gun back firing - no power
 

Bad distributor cap? There are a bunch of bad caps and rotor sets out
there. The rotors are too short so they work for a short time, then arc
out all over the place.

Oil drip onto the coil power connection or loose almost broken wire
there?

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)

Rusted wrote:
>
> Over the past 7-10 days I have been loosing power with my '83 258 engine to
> the point where it is difficult to drive and keep running. It feels like I
> am pulling a trailer, and I am getting rapid machine gun style backfiring
> through the muffler when I get around 2000 RPM. It has 215,000 miles so it
> is a little tired anyways. It felt like the timing had slipped, like
> possibly the timing chain had slipped, but when I use a timing light the
> mark is still in the ballpark of where it should be, so I don't believe that
> is the case. I re-adjusted the timing using only a vacuum gauge to get the
> max vacuum and it now idols better, but I still get the machine gun type
> back firing when I get over 2000 RPM.
>
> A few months ago I replaced the valve cover from a plastic cover to an
> aluminum cover to stop the constant oil leak I was having. In the process I
> swapped the valve bridges with the non-bolt style bridge since they were not
> needed any longer. When did replace those I torqued them down, and used the
> original nuts.
>
> The vacuum advance is still moving properly and has been well cleaned.
>
> Any ideas what is going on? My first idea of timing seems to be more or
> less ruled out. I am now leaning towards one of the rocker bolts has come
> loose. Any other ideas of what to look for or check?
>
> 83 CJ-7
>
> 258 I-6 engine
>
> MC2100 carb
>
> stock and original distrubutor

Re: machine gun back firing - no power
 

Bad distributor cap? There are a bunch of bad caps and rotor sets out
there. The rotors are too short so they work for a short time, then arc
out all over the place.

Oil drip onto the coil power connection or loose almost broken wire
there?

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)

Rusted wrote:
>
> Over the past 7-10 days I have been loosing power with my '83 258 engine to
> the point where it is difficult to drive and keep running. It feels like I
> am pulling a trailer, and I am getting rapid machine gun style backfiring
> through the muffler when I get around 2000 RPM. It has 215,000 miles so it
> is a little tired anyways. It felt like the timing had slipped, like
> possibly the timing chain had slipped, but when I use a timing light the
> mark is still in the ballpark of where it should be, so I don't believe that
> is the case. I re-adjusted the timing using only a vacuum gauge to get the
> max vacuum and it now idols better, but I still get the machine gun type
> back firing when I get over 2000 RPM.
>
> A few months ago I replaced the valve cover from a plastic cover to an
> aluminum cover to stop the constant oil leak I was having. In the process I
> swapped the valve bridges with the non-bolt style bridge since they were not
> needed any longer. When did replace those I torqued them down, and used the
> original nuts.
>
> The vacuum advance is still moving properly and has been well cleaned.
>
> Any ideas what is going on? My first idea of timing seems to be more or
> less ruled out. I am now leaning towards one of the rocker bolts has come
> loose. Any other ideas of what to look for or check?
>
> 83 CJ-7
>
> 258 I-6 engine
>
> MC2100 carb
>
> stock and original distrubutor

Re: machine gun back firing - no power
 

Bad distributor cap? There are a bunch of bad caps and rotor sets out
there. The rotors are too short so they work for a short time, then arc
out all over the place.

Oil drip onto the coil power connection or loose almost broken wire
there?

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)

Rusted wrote:
>
> Over the past 7-10 days I have been loosing power with my '83 258 engine to
> the point where it is difficult to drive and keep running. It feels like I
> am pulling a trailer, and I am getting rapid machine gun style backfiring
> through the muffler when I get around 2000 RPM. It has 215,000 miles so it
> is a little tired anyways. It felt like the timing had slipped, like
> possibly the timing chain had slipped, but when I use a timing light the
> mark is still in the ballpark of where it should be, so I don't believe that
> is the case. I re-adjusted the timing using only a vacuum gauge to get the
> max vacuum and it now idols better, but I still get the machine gun type
> back firing when I get over 2000 RPM.
>
> A few months ago I replaced the valve cover from a plastic cover to an
> aluminum cover to stop the constant oil leak I was having. In the process I
> swapped the valve bridges with the non-bolt style bridge since they were not
> needed any longer. When did replace those I torqued them down, and used the
> original nuts.
>
> The vacuum advance is still moving properly and has been well cleaned.
>
> Any ideas what is going on? My first idea of timing seems to be more or
> less ruled out. I am now leaning towards one of the rocker bolts has come
> loose. Any other ideas of what to look for or check?
>
> 83 CJ-7
>
> 258 I-6 engine
>
> MC2100 carb
>
> stock and original distrubutor

Re: machine gun back firing - no power
 

Also a longshot, but a very weak valve spring will show these symptoms as
well.

Chris

"Earle Horton" <Nurse-NOSPAM-Busters@msn.com> wrote in message
news:44abf6fe$0$23735$a82e2bb9@reader.athenanews.c om...
> Add plug wires to that.
>
> Earle
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:44ABECB3.C34888EE@sympatico.ca...
>> Bad distributor cap? There are a bunch of bad caps and rotor sets out
>> there. The rotors are too short so they work for a short time, then arc
>> out all over the place.
>>
>> Oil drip onto the coil power connection or loose almost broken wire
>> there?
>>
>> 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)
>>
>> Rusted wrote:
>> >
>> > Over the past 7-10 days I have been loosing power with my '83 258
>> > engine
> to
>> > the point where it is difficult to drive and keep running. It feels
> like I
>> > am pulling a trailer, and I am getting rapid machine gun style
> backfiring
>> > through the muffler when I get around 2000 RPM. It has 215,000 miles
> so it
>> > is a little tired anyways. It felt like the timing had slipped, like
>> > possibly the timing chain had slipped, but when I use a timing light
>> > the
>> > mark is still in the ballpark of where it should be, so I don't believe
> that
>> > is the case. I re-adjusted the timing using only a vacuum gauge to get
> the
>> > max vacuum and it now idols better, but I still get the machine gun
>> > type
>> > back firing when I get over 2000 RPM.
>> >
>> > A few months ago I replaced the valve cover from a plastic cover to an
>> > aluminum cover to stop the constant oil leak I was having. In the
> process I
>> > swapped the valve bridges with the non-bolt style bridge since they
>> > were
> not
>> > needed any longer. When did replace those I torqued them down, and
>> > used
> the
>> > original nuts.
>> >
>> > The vacuum advance is still moving properly and has been well cleaned.
>> >
>> > Any ideas what is going on? My first idea of timing seems to be more
> or
>> > less ruled out. I am now leaning towards one of the rocker bolts has
> come
>> > loose. Any other ideas of what to look for or check?
>> >
>> > 83 CJ-7
>> >
>> > 258 I-6 engine
>> >
>> > MC2100 carb
>> >
>> > stock and original distrubutor
>
>

Re: machine gun back firing - no power
 

Also a longshot, but a very weak valve spring will show these symptoms as
well.

Chris

"Earle Horton" <Nurse-NOSPAM-Busters@msn.com> wrote in message
news:44abf6fe$0$23735$a82e2bb9@reader.athenanews.c om...
> Add plug wires to that.
>
> Earle
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:44ABECB3.C34888EE@sympatico.ca...
>> Bad distributor cap? There are a bunch of bad caps and rotor sets out
>> there. The rotors are too short so they work for a short time, then arc
>> out all over the place.
>>
>> Oil drip onto the coil power connection or loose almost broken wire
>> there?
>>
>> 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)
>>
>> Rusted wrote:
>> >
>> > Over the past 7-10 days I have been loosing power with my '83 258
>> > engine
> to
>> > the point where it is difficult to drive and keep running. It feels
> like I
>> > am pulling a trailer, and I am getting rapid machine gun style
> backfiring
>> > through the muffler when I get around 2000 RPM. It has 215,000 miles
> so it
>> > is a little tired anyways. It felt like the timing had slipped, like
>> > possibly the timing chain had slipped, but when I use a timing light
>> > the
>> > mark is still in the ballpark of where it should be, so I don't believe
> that
>> > is the case. I re-adjusted the timing using only a vacuum gauge to get
> the
>> > max vacuum and it now idols better, but I still get the machine gun
>> > type
>> > back firing when I get over 2000 RPM.
>> >
>> > A few months ago I replaced the valve cover from a plastic cover to an
>> > aluminum cover to stop the constant oil leak I was having. In the
> process I
>> > swapped the valve bridges with the non-bolt style bridge since they
>> > were
> not
>> > needed any longer. When did replace those I torqued them down, and
>> > used
> the
>> > original nuts.
>> >
>> > The vacuum advance is still moving properly and has been well cleaned.
>> >
>> > Any ideas what is going on? My first idea of timing seems to be more
> or
>> > less ruled out. I am now leaning towards one of the rocker bolts has
> come
>> > loose. Any other ideas of what to look for or check?
>> >
>> > 83 CJ-7
>> >
>> > 258 I-6 engine
>> >
>> > MC2100 carb
>> >
>> > stock and original distrubutor
>
>

Re: machine gun back firing - no power
 

Also a longshot, but a very weak valve spring will show these symptoms as
well.

Chris

"Earle Horton" <Nurse-NOSPAM-Busters@msn.com> wrote in message
news:44abf6fe$0$23735$a82e2bb9@reader.athenanews.c om...
> Add plug wires to that.
>
> Earle
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:44ABECB3.C34888EE@sympatico.ca...
>> Bad distributor cap? There are a bunch of bad caps and rotor sets out
>> there. The rotors are too short so they work for a short time, then arc
>> out all over the place.
>>
>> Oil drip onto the coil power connection or loose almost broken wire
>> there?
>>
>> 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)
>>
>> Rusted wrote:
>> >
>> > Over the past 7-10 days I have been loosing power with my '83 258
>> > engine
> to
>> > the point where it is difficult to drive and keep running. It feels
> like I
>> > am pulling a trailer, and I am getting rapid machine gun style
> backfiring
>> > through the muffler when I get around 2000 RPM. It has 215,000 miles
> so it
>> > is a little tired anyways. It felt like the timing had slipped, like
>> > possibly the timing chain had slipped, but when I use a timing light
>> > the
>> > mark is still in the ballpark of where it should be, so I don't believe
> that
>> > is the case. I re-adjusted the timing using only a vacuum gauge to get
> the
>> > max vacuum and it now idols better, but I still get the machine gun
>> > type
>> > back firing when I get over 2000 RPM.
>> >
>> > A few months ago I replaced the valve cover from a plastic cover to an
>> > aluminum cover to stop the constant oil leak I was having. In the
> process I
>> > swapped the valve bridges with the non-bolt style bridge since they
>> > were
> not
>> > needed any longer. When did replace those I torqued them down, and
>> > used
> the
>> > original nuts.
>> >
>> > The vacuum advance is still moving properly and has been well cleaned.
>> >
>> > Any ideas what is going on? My first idea of timing seems to be more
> or
>> > less ruled out. I am now leaning towards one of the rocker bolts has
> come
>> > loose. Any other ideas of what to look for or check?
>> >
>> > 83 CJ-7
>> >
>> > 258 I-6 engine
>> >
>> > MC2100 carb
>> >
>> > stock and original distrubutor
>
>

Re: machine gun back firing - no power
 

Add plug wires to that.

Earle

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:44ABECB3.C34888EE@sympatico.ca...
> Bad distributor cap? There are a bunch of bad caps and rotor sets out
> there. The rotors are too short so they work for a short time, then arc
> out all over the place.
>
> Oil drip onto the coil power connection or loose almost broken wire
> there?
>
> 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)
>
> Rusted wrote:
> >
> > Over the past 7-10 days I have been loosing power with my '83 258 engine
to
> > the point where it is difficult to drive and keep running. It feels
like I
> > am pulling a trailer, and I am getting rapid machine gun style
backfiring
> > through the muffler when I get around 2000 RPM. It has 215,000 miles
so it
> > is a little tired anyways. It felt like the timing had slipped, like
> > possibly the timing chain had slipped, but when I use a timing light the
> > mark is still in the ballpark of where it should be, so I don't believe
that
> > is the case. I re-adjusted the timing using only a vacuum gauge to get
the
> > max vacuum and it now idols better, but I still get the machine gun type
> > back firing when I get over 2000 RPM.
> >
> > A few months ago I replaced the valve cover from a plastic cover to an
> > aluminum cover to stop the constant oil leak I was having. In the
process I
> > swapped the valve bridges with the non-bolt style bridge since they were
not
> > needed any longer. When did replace those I torqued them down, and used
the
> > original nuts.
> >
> > The vacuum advance is still moving properly and has been well cleaned.
> >
> > Any ideas what is going on? My first idea of timing seems to be more
or
> > less ruled out. I am now leaning towards one of the rocker bolts has
come
> > loose. Any other ideas of what to look for or check?
> >
> > 83 CJ-7
> >
> > 258 I-6 engine
> >
> > MC2100 carb
> >
> > stock and original distrubutor

Re: machine gun back firing - no power
 

Add plug wires to that.

Earle

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:44ABECB3.C34888EE@sympatico.ca...
> Bad distributor cap? There are a bunch of bad caps and rotor sets out
> there. The rotors are too short so they work for a short time, then arc
> out all over the place.
>
> Oil drip onto the coil power connection or loose almost broken wire
> there?
>
> 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)
>
> Rusted wrote:
> >
> > Over the past 7-10 days I have been loosing power with my '83 258 engine
to
> > the point where it is difficult to drive and keep running. It feels
like I
> > am pulling a trailer, and I am getting rapid machine gun style
backfiring
> > through the muffler when I get around 2000 RPM. It has 215,000 miles
so it
> > is a little tired anyways. It felt like the timing had slipped, like
> > possibly the timing chain had slipped, but when I use a timing light the
> > mark is still in the ballpark of where it should be, so I don't believe
that
> > is the case. I re-adjusted the timing using only a vacuum gauge to get
the
> > max vacuum and it now idols better, but I still get the machine gun type
> > back firing when I get over 2000 RPM.
> >
> > A few months ago I replaced the valve cover from a plastic cover to an
> > aluminum cover to stop the constant oil leak I was having. In the
process I
> > swapped the valve bridges with the non-bolt style bridge since they were
not
> > needed any longer. When did replace those I torqued them down, and used
the
> > original nuts.
> >
> > The vacuum advance is still moving properly and has been well cleaned.
> >
> > Any ideas what is going on? My first idea of timing seems to be more
or
> > less ruled out. I am now leaning towards one of the rocker bolts has
come
> > loose. Any other ideas of what to look for or check?
> >
> > 83 CJ-7
> >
> > 258 I-6 engine
> >
> > MC2100 carb
> >
> > stock and original distrubutor

Re: machine gun back firing - no power
 

Add plug wires to that.

Earle

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:44ABECB3.C34888EE@sympatico.ca...
> Bad distributor cap? There are a bunch of bad caps and rotor sets out
> there. The rotors are too short so they work for a short time, then arc
> out all over the place.
>
> Oil drip onto the coil power connection or loose almost broken wire
> there?
>
> 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)
>
> Rusted wrote:
> >
> > Over the past 7-10 days I have been loosing power with my '83 258 engine
to
> > the point where it is difficult to drive and keep running. It feels
like I
> > am pulling a trailer, and I am getting rapid machine gun style
backfiring
> > through the muffler when I get around 2000 RPM. It has 215,000 miles
so it
> > is a little tired anyways. It felt like the timing had slipped, like
> > possibly the timing chain had slipped, but when I use a timing light the
> > mark is still in the ballpark of where it should be, so I don't believe
that
> > is the case. I re-adjusted the timing using only a vacuum gauge to get
the
> > max vacuum and it now idols better, but I still get the machine gun type
> > back firing when I get over 2000 RPM.
> >
> > A few months ago I replaced the valve cover from a plastic cover to an
> > aluminum cover to stop the constant oil leak I was having. In the
process I
> > swapped the valve bridges with the non-bolt style bridge since they were
not
> > needed any longer. When did replace those I torqued them down, and used
the
> > original nuts.
> >
> > The vacuum advance is still moving properly and has been well cleaned.
> >
> > Any ideas what is going on? My first idea of timing seems to be more
or
> > less ruled out. I am now leaning towards one of the rocker bolts has
come
> > loose. Any other ideas of what to look for or check?
> >
> > 83 CJ-7
> >
> > 258 I-6 engine
> >
> > MC2100 carb
> >
> > stock and original distrubutor