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
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: N>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 ?
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
R>
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
R>
ok....
So if the return outlet is > The carb doesn't matter unless it won't run at the CJ carb's pressure
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
R>
Mike Romain did pass the time by typing:
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.
Jeep figured the external filter with the return line was a better option I guess, but it is the same idea. Vapor lock is an issue on the I6 because the gas line runs up over top of the valve cover and across the manifolds. The return line was the fix.
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
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 ?
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
R>
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 >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 Roma> I have never taken the two apart when changing the gaskets....
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
R>
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