'79 CJ5 gasline question.

Hi Doug,
That was a built in filter bypass, responsible for many needle
valve failures, then all most no one tighten the fittings correctly
which then vibrated loose and cause an engine fi
http://www.carburetorfactory.com/expvw27.html
God Bless America, Bill O|||||||O
http://www.billhughes.com/

DougW wrote:
>
> Dunno if this applies but in the old rochester 4M4 quadrasuck there
> was a fuel filter with built-in check valve right in the carb
> Use the one without a check valve and it will drain back to the tank.
>
> --
> DougW

Right... I understand.

That is how I installed the filter. The center bigger nipple goes to
the carb. The smaller one on top is the return line.

I had the filter always installed like that... but when I start it
after a bit sitting still it seems that the fuel in the line drained
back to the tank. It did that with the new and the old carburator.
After I installed a new pump it still did that.

I am wondering if there mybe is a vacuum in the tank that sucks the gas
back ?


> Let's try that again.... ;-)
>
> The center outlet of the filter goes to the carb. The return line needs
> to be at the top of the filter on the smaller nipple. The two nipples
> are different sizes.
>
> Then when the carb is full, the gas raises to the top of the filter and
> goes back the return line to the tank so the return line is up top.
>
> This prevents vapor lock also because when you shut it down hot, gas can
> boil in the line which causes the vapor lock and no start like you are
> experiencing.
>
> If the return line is down, then the gas is free to run back to the tank
> which vapor locks it. It will then need two primes of a quarter cup of
> gas for the pump to pick it up if you want to save your battery and
> starter....
>
> Mike
>
>
> Ron Croonenberg wrote:
>
>>ok....
>>
>>So if the return outlet is on top and the engine won't start (after a
>>day of sitting still) unless I crank it for 30 secs or so.. then what
>>could the problem ? To me it seems that it is acting like there's no fuel.
>>
>>Mike Romain wrote:
>>
>>
>>>The carb doesn't matter unless it won't run at the CJ carb's pressure
>>>which is a different problem. It is just physics with the gas lines.
>>>If the return is up top, gas won't syphon.
>>>
>>>There was a thread back a while ago about the pressure that filter is
>>>set for. Some place around 5 psi I think. It is set by the hole size
>>>in the return line outlet. Lower pressure could be had by drilling out
>>>the blocking plate.
>>>
>>>Mike
>>>
>>>Ron Croonenberg wrote:
>>>
>>>
>>>>I just checked the CJ the off center outlet is on top
>>>>I don't have the original carb anymore I have that weber one
>>>>
>>>>Mike Romain wrote:
>>>>
>>>>
>>>>
>>>>>The parts stores around here all carry the CJ gas filter. The YJ up to
>>>>>91 uses the same one. Once it is in place it won't rotate unless
>>>>>bumped, but it 'is' easy to rotate if you are mucking about with the
>>>>>carb.
>>>>>
>>>>>I find the Haynes CJ manual to be a very good one. It covers pretty
>>>>>much everything accurately.
>>>>>
>>>>>The owners manual even mentions the right way to install the fuel
>>>>>filter.
>>>>>
>>>>>Mike
>>>>>
>>>>>Ron Croonenberg wrote:
>>>>>
>>>>>
>>>>>
>>>>>>Ok, let me check that.
>>>>>>
>>>>>>It always had that problem, also when I replaced the fuel pump.
>>>>>>I can check to see if the filter is upside down or not.
>>>>>>
>>>>>>If it is the fuelfilter doing that, are there any better ones ? How do I
>>>>>>know I have the correct one ? (Is there a pic of one somewhere ?
>>>>>>
>>>>>>Is there a "everything you wanted to ask about your CJ's fuel lines but
>>>>>>were afraid to ask" page somewhere ?
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>That usually happens because the gas filter is in upside down. The
>>>>>>>filter has two outlets, the center outlet leads to the carb and the
>>>>>>>'top' one leads to the return line. If the return line isn't at the
>>>>>>>top, gas will syphon back to the tank air locking the line and they are
>>>>>>>real buggers to start up.
>>>>>>>
>>>>>>>There also is a valve on the fuel pump likely to stop backflow. You
>>>>>>>could first make sure the filter is right, then take the line off the
>>>>>>>pump intake to see if the gas all comes out.
>>>>>>>
>>>>>>>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)
>>>>>>>
>>>>>>>
>>>>>>>Ron Croonenberg wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>Hi all,
>>>>>>>>
>>>>>>>>it seems that if my '79 CJ5 is sitting for a while that the gas
>>>>>>>>runs through the line back to the tank.
>>>>>>>>
>>>>>>>>That means that after it has been sitting for a while. I have to crank
>>>>>>>>it for a while before it starts. (if it sits for a day or so.. I have
>>>>>>>>to crank it quite a bit. If it sits there for an hour or 2 there's no
>>>>>>>>problem
>>>>>>>>
>>>>>>>>I replaced all the hoses.
>>>>>>>>
>>>>>>>>How does the gascap work ? is it supposed to seal the gastank,
>>>>>>>>or doesn't it matter ? The gascap I have is probably the original.
>>>>>>>>
>>>>>>>>thanks,
>>>>>>>>
>>>>>>>>Ron

I would next say that it can be caused by a pinhole leak in the gas line
on the suction side of the pump. It can be a small enough hole that it
won't drip on the ground, but it will let air in, but didn't you mention
you have new lines too?

How is your gas tank vent? If the air filter on the vent gets plugged
up, the tank can develop a vacuum on it. This can get bad enough to
cause high speed bogs and even imitate running out of gas.

The charcoal canister is the vent. The air filter is about two bucks
and is a real bitch to change the first time. I had to use a hammer and
chisel to get my first one out. The new ones just tuck in.

Mike

Ron Croonenberg wrote:
>
> Right... I understand.
>
> That is how I installed the filter. The center bigger nipple goes to
> the carb. The smaller one on top is the return line.
>
> I had the filter always installed like that... but when I start it
> after a bit sitting still it seems that the fuel in the line drained
> back to the tank. It did that with the new and the old carburator.
> After I installed a new pump it still did that.
>
> I am wondering if there mybe is a vacuum in the tank that sucks the gas
> back ?
>
> > Let's try that again.... ;-)
> >
> > The center outlet of the filter goes to the carb. The return line needs
> > to be at the top of the filter on the smaller nipple. The two nipples
> > are different sizes.
> >
> > Then when the carb is full, the gas raises to the top of the filter and
> > goes back the return line to the tank so the return line is up top.
> >
> > This prevents vapor lock also because when you shut it down hot, gas can
> > boil in the line which causes the vapor lock and no start like you are
> > experiencing.
> >
> > If the return line is down, then the gas is free to run back to the tank
> > which vapor locks it. It will then need two primes of a quarter cup of
> > gas for the pump to pick it up if you want to save your battery and
> > starter....
> >
> > Mike
> >
> >
> > Ron Croonenberg wrote:
> >
> >>ok....
> >>
> >>So if the return outlet is on top and the engine won't start (after a
> >>day of sitting still) unless I crank it for 30 secs or so.. then what
> >>could the problem ? To me it seems that it is acting like there's no fuel.
> >>
> >>Mike Romain wrote:
> >>
> >>
> >>>The carb doesn't matter unless it won't run at the CJ carb's pressure
> >>>which is a different problem. It is just physics with the gas lines.
> >>>If the return is up top, gas won't syphon.
> >>>
> >>>There was a thread back a while ago about the pressure that filter is
> >>>set for. Some place around 5 psi I think. It is set by the hole size
> >>>in the return line outlet. Lower pressure could be had by drilling out
> >>>the blocking plate.
> >>>
> >>>Mike
> >>>
> >>>Ron Croonenberg wrote:
> >>>
> >>>
> >>>>I just checked the CJ the off center outlet is on top
> >>>>I don't have the original carb anymore I have that weber one
> >>>>
> >>>>Mike Romain wrote:
> >>>>
> >>>>
> >>>>
> >>>>>The parts stores around here all carry the CJ gas filter. The YJ up to
> >>>>>91 uses the same one. Once it is in place it won't rotate unless
> >>>>>bumped, but it 'is' easy to rotate if you are mucking about with the
> >>>>>carb.
> >>>>>
> >>>>>I find the Haynes CJ manual to be a very good one. It covers pretty
> >>>>>much everything accurately.
> >>>>>
> >>>>>The owners manual even mentions the right way to install the fuel
> >>>>>filter.
> >>>>>
> >>>>>Mike
> >>>>>
> >>>>>Ron Croonenberg wrote:
> >>>>>
> >>>>>
> >>>>>
> >>>>>>Ok, let me check that.
> >>>>>>
> >>>>>>It always had that problem, also when I replaced the fuel pump.
> >>>>>>I can check to see if the filter is upside down or not.
> >>>>>>
> >>>>>>If it is the fuelfilter doing that, are there any better ones ? How do I
> >>>>>>know I have the correct one ? (Is there a pic of one somewhere ?
> >>>>>>
> >>>>>>Is there a "everything you wanted to ask about your CJ's fuel lines but
> >>>>>>were afraid to ask" page somewhere ?
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>>That usually happens because the gas filter is in upside down. The
> >>>>>>>filter has two outlets, the center outlet leads to the carb and the
> >>>>>>>'top' one leads to the return line. If the return line isn't at the
> >>>>>>>top, gas will syphon back to the tank air locking the line and they are
> >>>>>>>real buggers to start up.
> >>>>>>>
> >>>>>>>There also is a valve on the fuel pump likely to stop backflow. You
> >>>>>>>could first make sure the filter is right, then take the line off the
> >>>>>>>pump intake to see if the gas all comes out.
> >>>>>>>
> >>>>>>>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)
> >>>>>>>
> >>>>>>>
> >>>>>>>Ron Croonenberg wrote:
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>>Hi all,
> >>>>>>>>
> >>>>>>>>it seems that if my '79 CJ5 is sitting for a while that the gas
> >>>>>>>>runs through the line back to the tank.
> >>>>>>>>
> >>>>>>>>That means that after it has been sitting for a while. I have to crank
> >>>>>>>>it for a while before it starts. (if it sits for a day or so.. I have
> >>>>>>>>to crank it quite a bit. If it sits there for an hour or 2 there's no
> >>>>>>>>problem
> >>>>>>>>
> >>>>>>>>I replaced all the hoses.
> >>>>>>>>
> >>>>>>>>How does the gascap work ? is it supposed to seal the gastank,
> >>>>>>>>or doesn't it matter ? The gascap I have is probably the original.
> >>>>>>>>
> >>>>>>>>thanks,
> >>>>>>>>
> >>>>>>>>Ron

Ok...now you mention it... that might be it. I have a filter lieng
around somewhere I think.

Mike Romain wrote:

> I would next say that it can be caused by a pinhole leak in the gas line
> on the suction side of the pump. It can be a small enough hole that it
> won't drip on the ground, but it will let air in, but didn't you mention
> you have new lines too?
>
> How is your gas tank vent? If the air filter on the vent gets plugged
> up, the tank can develop a vacuum on it. This can get bad enough to
> cause high speed bogs and even imitate running out of gas.
>
> The charcoal canister is the vent. The air filter is about two bucks
> and is a real bitch to change the first time. I had to use a hammer and
> chisel to get my first one out. The new ones just tuck in.
>
> Mike
>
> Ron Croonenberg wrote:
>
>>Right... I understand.
>>
>>That is how I installed the filter. The center bigger nipple goes to
>>the carb. The smaller one on top is the return line.
>>
>>I had the filter always installed like that... but when I start it
>>after a bit sitting still it seems that the fuel in the line drained
>>back to the tank. It did that with the new and the old carburator.
>>After I installed a new pump it still did that.
>>
>>I am wondering if there mybe is a vacuum in the tank that sucks the gas
>>back ?
>>
>>
>>>Let's try that again.... ;-)
>>>
>>>The center outlet of the filter goes to the carb. The return line needs
>>>to be at the top of the filter on the smaller nipple. The two nipples
>>>are different sizes.
>>>
>>>Then when the carb is full, the gas raises to the top of the filter and
>>>goes back the return line to the tank so the return line is up top.
>>>
>>>This prevents vapor lock also because when you shut it down hot, gas can
>>>boil in the line which causes the vapor lock and no start like you are
>>>experiencing.
>>>
>>>If the return line is down, then the gas is free to run back to the tank
>>>which vapor locks it. It will then need two primes of a quarter cup of
>>>gas for the pump to pick it up if you want to save your battery and
>>>starter....
>>>
>>>Mike
>>>
>>>
>>>Ron Croonenberg wrote:
>>>
>>>
>>>>ok....
>>>>
>>>>So if the return outlet is on top and the engine won't start (after a
>>>>day of sitting still) unless I crank it for 30 secs or so.. then what
>>>>could the problem ? To me it seems that it is acting like there's no fuel.
>>>>
>>>>Mike Romain wrote:
>>>>
>>>>
>>>>
>>>>>The carb doesn't matter unless it won't run at the CJ carb's pressure
>>>>>which is a different problem. It is just physics with the gas lines.
>>>>>If the return is up top, gas won't syphon.
>>>>>
>>>>>There was a thread back a while ago about the pressure that filter is
>>>>>set for. Some place around 5 psi I think. It is set by the hole size
>>>>>in the return line outlet. Lower pressure could be had by drilling out
>>>>>the blocking plate.
>>>>>
>>>>>Mike
>>>>>
>>>>>Ron Croonenberg wrote:
>>>>>
>>>>>
>>>>>
>>>>>>I just checked the CJ the off center outlet is on top
>>>>>>I don't have the original carb anymore I have that weber one
>>>>>>
>>>>>>Mike Romain wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>The parts stores around here all carry the CJ gas filter. The YJ up to
>>>>>>>91 uses the same one. Once it is in place it won't rotate unless
>>>>>>>bumped, but it 'is' easy to rotate if you are mucking about with the
>>>>>>>carb.
>>>>>>>
>>>>>>>I find the Haynes CJ manual to be a very good one. It covers pretty
>>>>>>>much everything accurately.
>>>>>>>
>>>>>>>The owners manual even mentions the right way to install the fuel
>>>>>>>filter.
>>>>>>>
>>>>>>>Mike
>>>>>>>
>>>>>>>Ron Croonenberg wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>Ok, let me check that.
>>>>>>>>
>>>>>>>>It always had that problem, also when I replaced the fuel pump.
>>>>>>>>I can check to see if the filter is upside down or not.
>>>>>>>>
>>>>>>>>If it is the fuelfilter doing that, are there any better ones ? How do I
>>>>>>>>know I have the correct one ? (Is there a pic of one somewhere ?
>>>>>>>>
>>>>>>>>Is there a "everything you wanted to ask about your CJ's fuel lines but
>>>>>>>>were afraid to ask" page somewhere ?
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>>That usually happens because the gas filter is in upside down. The
>>>>>>>>>filter has two outlets, the center outlet leads to the carb and the
>>>>>>>>>'top' one leads to the return line. If the return line isn't at the
>>>>>>>>>top, gas will syphon back to the tank air locking the line and they are
>>>>>>>>>real buggers to start up.
>>>>>>>>>
>>>>>>>>>There also is a valve on the fuel pump likely to stop backflow. You
>>>>>>>>>could first make sure the filter is right, then take the line off the
>>>>>>>>>pump intake to see if the gas all comes out.
>>>>>>>>>
>>>>>>>>>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)
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>Ron Croonenberg wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>>Hi all,
>>>>>>>>>>
>>>>>>>>>>it seems that if my '79 CJ5 is sitting for a while that the gas
>>>>>>>>>>runs through the line back to the tank.
>>>>>>>>>>
>>>>>>>>>>That means that after it has been sitting for a while. I have to crank
>>>>>>>>>>it for a while before it starts. (if it sits for a day or so.. I have
>>>>>>>>>>to crank it quite a bit. If it sits there for an hour or 2 there's no
>>>>>>>>>>problem
>>>>>>>>>>
>>>>>>>>>>I replaced all the hoses.
>>>>>>>>>>
>>>>>>>>>>How does the gascap work ? is it supposed to seal the gastank,
>>>>>>>>>>or doesn't it matter ? The gascap I have is probably the original.
>>>>>>>>>>
>>>>>>>>>>thanks,
>>>>>>>>>>
>>>>>>>>>>Ron

I need to replace the manifold and exhaust gaskets (when I show up
people start looking around to see if there's farm equipment showing up)

Anyway, the instruction sheet that came with the gasket kit (felpro)
says that the intake maniold needs to be seperated from the exhaust
manifold. How is that done ? Are there a few bolts that line the two
up or so ?

also, in the store they told me NOT to use silicon or anything.

Ron

I have never taken the two apart when changing the gaskets....

There are 4 bolts 'under' the carb area holding them together I believe.

The gasket goes on dry.

I also have found that those long 6's like to come loose once after
torquing them on. I tighten them up a day or so later depending on the
miles I drive it. Maybe yours is just loose now?

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)

Ron Croonenberg wrote:
>
> I need to replace the manifold and exhaust gaskets (when I show up
> people start looking around to see if there's farm equipment showing up)
>
> Anyway, the instruction sheet that came with the gasket kit (felpro)
> says that the intake maniold needs to be seperated from the exhaust
> manifold. How is that done ? Are there a few bolts that line the two
> up or so ?
>
> also, in the store they told me NOT to use silicon or anything.
>
> Ron

might be.. I just want to redo the whole thing. I had it done 3 years
ago (thought if I had a shhop do it, they'd do it right). they used
silicone.

Do you take the carb and all the crap off when you redo the gasket ?

(I think that the biggest leak is where the exhaust pipe comes in (but
there is another one too I am sure0

Ron


Mike Romain wrote:

> I have never taken the two apart when changing the gaskets....
>
> There are 4 bolts 'under' the carb area holding them together I believe.
>
> The gasket goes on dry.
>
> I also have found that those long 6's like to come loose once after
> torquing them on. I tighten them up a day or so later depending on the
> miles I drive it. Maybe yours is just loose now?
>
> 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)
>
> Ron Croonenberg wrote:
>
>>I need to replace the manifold and exhaust gaskets (when I show up
>>people start looking around to see if there's farm equipment showing up)
>>
>>Anyway, the instruction sheet that came with the gasket kit (felpro)
>>says that the intake maniold needs to be seperated from the exhaust
>>manifold. How is that done ? Are there a few bolts that line the two
>>up or so ?
>>
>>also, in the store they told me NOT to use silicon or anything.
>>
>>Ron

It is easier to do with the carb out of the way... A 'wobbler'
extension also helps out a 'lot'.

If you are taking it all apart, then the last 4 nuts to tighten down are
the ones between the manifolds.

A shop used silicone on a manifold? What a bunch of hacks! They
obviously just did a patch job and pocketed the cash for the 'new'
gasket you were supposed to get.

Do you have the book for the torque pattern?

Mike

Ron Croonenberg wrote:
>
> might be.. I just want to redo the whole thing. I had it done 3 years
> ago (thought if I had a shhop do it, they'd do it right). they used
> silicone.
>
> Do you take the carb and all the crap off when you redo the gasket ?
>
> (I think that the biggest leak is where the exhaust pipe comes in (but
> there is another one too I am sure0
>
> Ron
>
> Mike Romain wrote:
>
> > I have never taken the two apart when changing the gaskets....
> >
> > There are 4 bolts 'under' the carb area holding them together I believe.
> >
> > The gasket goes on dry.
> >
> > I also have found that those long 6's like to come loose once after
> > torquing them on. I tighten them up a day or so later depending on the
> > miles I drive it. Maybe yours is just loose now?
> >
> > 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)
> >
> > Ron Croonenberg wrote:
> >
> >>I need to replace the manifold and exhaust gaskets (when I show up
> >>people start looking around to see if there's farm equipment showing up)
> >>
> >>Anyway, the instruction sheet that came with the gasket kit (felpro)
> >>says that the intake maniold needs to be seperated from the exhaust
> >>manifold. How is that done ? Are there a few bolts that line the two
> >>up or so ?
> >>
> >>also, in the store they told me NOT to use silicon or anything.
> >>
> >>Ron