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Engine stalls, cause unknown

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Engine stalls, cause unknown
I got one. MR 252. All 1300 pages and yes, I have it in hard copy. You're right, it's much better than the Chilton I have. I'll look up the roll over valve. I have started looking for vacuum leaks but not finished. Thanks
 
Good mon you for hav'n the MR-252. :chug:
Keep us up dated.:cool:
LG
 
B3uhbp, in the Chilton book on page 247, is the layout for the gas tank vent system past the charcoal canister. I don't think you will find that in the FSM. If you have all that stuff you are in good shape. Do you have the 15 or 20 gal. tank? as the check valves are different.
 
Torxhead said:
B3uhbp, in the Chilton book on page 247, is the layout for the gas tank vent system past the charcoal canister. I don't think you will find that in the FSM. If you have all that stuff you are in good shape. Do you have the 15 or 20 gal. tank? as the check valves are different.
Click to expand...

20 gallon.
 
O.K. so you should have the two check valves on top of it, as shown in your Chilton manual. The charcoal cannister has a hose going to them. There is a vent/vacumn line to that cannister that provides a bit of vacuum to help romove the vapors from the gas tank. With that setup and a vented gas cap you should have a well vented system, provided everything is working correctly. Make sure that the filter on the bottom of the cannister is clean and not clogged with debris.
 
His gas cap should not be ventilated. If it is he will fail emissions every time.

The difference in valves is related to the year of manufacture. My '75 is required to have only one valve, newer CJ's have two. I believe one stops the charcoal canister from being filled with fuel and the other keeps the return line from back feeding. All of this is activated during a roll over accident.
 
Torxhead said:
O.K. so you should have the two check valves on top of it, as shown in your Chilton manual. The charcoal cannister has a hose going to them. There is a vent/vacumn line to that cannister that provides a bit of vacuum to help romove the vapors from the gas tank. With that setup and a vented gas cap you should have a well vented system, provided everything is working correctly. Make sure that the filter on the bottom of the cannister is clean and not clogged with debris.[/QUOTE

So you're saying the check valves are on top of the tank? Also, I said I had a Chilton manual but it is a Haynes and it doesn't show these check valves. Also, the charcoal canister had been disconnected along with the MCU and most of the vacuum system. While trying to sleep last night I remembered that a couple of months ago I dropped the tank looking for a rattle. When I bolted it back up I kept pinching a fuel line and cutting off fuel flow which killed the engine. Took me several attempts to get it to run without dying. It occurred to me that I could have pinched a vent or return line which didn't cause a problem until the weather warmed up. So, this morning I lowered the tank by 1/4 to 5/16 just to see if it would have any effect. Obviously, the right way to do this would be to know where the flex lines lay on top of the tank so they don't get squeezed. Maybe just a desperation move but worth a try. Thoughts?
Click to expand...
 
Did you ck for vacuum leaks yet? :confused:
The valves are in the left rear fender-well.
Get that charcoal canister plug'd back in to your system.
LG
 
I finally got to checking for vacuum leaks Using the soapy water. Also checked all the carb and manifold bolts. Didn't find any issues.
 
That's good. :chug:
Do you have to SMOG test this Jeep, where you live?
LG
 
You Stated: So you're saying the check valves are on top of the tank? Also, I said I had a Chilton manual but it is a Haynes and it doesn't show these check valves. Also, the charcoal canister had been disconnected along with the MCU and most of the vacuum system. While trying to sleep last night I remembered that a couple of months ago I dropped the tank looking for a rattle. When I bolted it back up I kept pinching a fuel line and cutting off fuel flow which killed the engine. Took me several attempts to get it to run without dying. It occurred to me that I could have pinched a vent or return line which didn't cause a problem until the weather warmed up. So, this morning I lowered the tank by 1/4 to 5/16 just to see if it would have any effect. Obviously, the right way to do this would be to know where the flex lines lay on top of the tank so they don't get squeezed. Maybe just a desperation move but worth a try. Thoughts?[/QUOTE]

I hope what I am stating here is correct. so if anyone wants to correct me please do so. There is a layout of the 15 gal. tank vent system on page 6-2
in the Haynes manual to give you an idea. On that tank the check valves are stuffed under the rear of the drivers side. For the 20 gal. tank, there are two check valves on top teeing together and hosed to the "Tank" outlet on the charcoal canister. So if the fuel vent line is pinched, it would cut off the vent system and could give you issues as you have described. You could just stuff a rag in your gas tank filler, which would vent it, to verify that you do have a venting problem. Then go for a drive and see how that works, just don't get caught by the cops or get close to anything that could make your CJ act like a Molotov Cocktail.
 
Lumpy Grits said:
That's good. :chug:
Do you have to SMOG test this Jeep, where you live?
LG
Click to expand...

No smog test TX. Next year I will register it as an antique and it will never have to be inspected again. Woo Hoo!
 
Torxhead said:
You Stated: So you're saying the check valves are on top of the tank? Also, I said I had a Chilton manual but it is a Haynes and it doesn't show these check valves. Also, the charcoal canister had been disconnected along with the MCU and most of the vacuum system. While trying to sleep last night I remembered that a couple of months ago I dropped the tank looking for a rattle. When I bolted it back up I kept pinching a fuel line and cutting off fuel flow which killed the engine. Took me several attempts to get it to run without dying. It occurred to me that I could have pinched a vent or return line which didn't cause a problem until the weather warmed up. So, this morning I lowered the tank by 1/4 to 5/16 just to see if it would have any effect. Obviously, the right way to do this would be to know where the flex lines lay on top of the tank so they don't get squeezed. Maybe just a desperation move but worth a try. Thoughts?
Click to expand...

I hope what I am stating here is correct. so if anyone wants to correct me please do so. There is a layout of the 15 gal. tank vent system on page 6-2
in the Haynes manual to give you an idea. On that tank the check valves are stuffed under the rear of the drivers side. For the 20 gal. tank, there are two check valves on top teeing together and hosed to the "Tank" outlet on the charcoal canister. So if the fuel vent line is pinched, it would cut off the vent system and could give you issues as you have described. You could just stuff a rag in your gas tank filler, which would vent it, to verify that you do have a venting problem. Then go for a drive and see how that works, just don't get caught by the cops or get close to anything that could make your CJ act like a Molotov Cocktail.[/QUOTE]

I found the tank diagram in the Haynes manual, thanks. I have searched but can not find any check valve or roll over valve. I can only assume they were removed by the PO. To test your idea re: the rag in the the tank, I simply removed the part of the gas cap that restricts air flow so air can move freely. No impact. That said, I am cautiously optimistic that my lowering of the tank has cured the problem but I will need to drive it more to be sure. If anyone can provide tips on how to positions the flex fuel lines on top of the tank to ensure no pinching I'd appreciate it. Thanks for all the help.
 
The check valves in the 20 gal. tank are fairly small and prevent gasoline from flowing out while letting the tank vent. I was able to get some clearance between the bed of the Jeep and the gas tank by installing a 1" body lift, So my fuel and return lines have plenty of clearance. You just might get some more clearance in there by installing a set of replacement body mounts as yours are probably shot by now if they are the originals.
So, I take it with that extra venting in your fuel cap the engine stalling still persists. So, you are going to have to move on and find something else that is causing that problem. I see where you checked the coil, an hei does have a good one also. I have heard of cracks in the rubber fuel inlet lines causing issues also, it has to be something.
 
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Torxhead said:
The check valves in the 20 gal. tank are fairly small and prevent gasoline from flowing out while letting the tank vent. I was able to get some clearance between the bed of the Jeep and the gas tank by installing a 1" body lift, So my fuel and return lines have plenty of clearance. You just might get some more clearance in there by installing a set of replacement body mounts as yours are probably shot by now if they are the originals.
So, I take it with that extra venting in your fuel cap the engine stalling still persists. So, you are going to have to move on and find something else that is causing that problem. I see where you checked the coil, an hei does have a good one also. I have heard of cracks in the rubber fuel inlet lines causing issues also, it has to be something.
Click to expand...

Yes it still persisted after cap mod. I'm hopeful that the tank lowering I did resolved the problem but it needs to be driven a bit before I can be sure.
 
Unless you had a pinched line at the tank. Nut'n will change.
Again I will say-Get rid of that pressure regulator on the fender.
Reconnect the canister that is plugged off, and your issue should be resolved

LG
 
Torxhead said:
The check valves in the 20 gal. tank are fairly small and prevent gasoline from flowing out while letting the tank vent. I was able to get some clearance between the bed of the Jeep and the gas tank by installing a 1" body lift, So my fuel and return lines have plenty of clearance. You just might get some more clearance in there by installing a set of replacement body mounts as yours are probably shot by now if they are the originals.
So, I take it with that extra venting in your fuel cap the engine stalling still persists. So, you are going to have to move on and find something else that is causing that problem. I see where you checked the coil, an hei does have a good one also. I have heard of cracks in the rubber fuel inlet lines causing issues also, it has to be something.
Click to expand...

Well it was about 80 degrees out yesterday and I put nearly 100 miles on the jeep. No issues. I consistently checked the fuel pressure with no decrease. When I removed the gas cap, no pressure and no vacuum evident. Dare I say it, it may be fixed. It certainly appears that I pinched a vent line when I dropped my tank 2 to 3 months ago but the warm weather made it manifest itself. When I lowered the tank ALL symptoms disappeared. Hallelujah!
 
Did you check that fuel tank vacuum with a non-modified cap yet? Glad to hear that it at least seems to be fixed. If you are going to be using full pressure of 4-5 psi you might as well ditch the regulator as suggested. Just use the gauge as a temporary inspection tool as using one full time can be hard on its accuracy. You could rig up a tee fitting on your fuel line and leave it plugged up when not in use. Looking at where the see-thru fuel filter is installed it really makes no sense since it is beyond the 3 hole oem style filter. That would be a good spot to install that tee fitting for fuel pressure that I just suggested. When I was running one of those see thru filters it was located just before the pump and was used to check for water in the fuel tank but only had one incident where I did spot water in it.
 
b3uhbp said:
Well it was about 80 degrees out yesterday and I put nearly 100 miles on the jeep. No issues. I consistently checked the fuel pressure with no decrease. When I removed the gas cap, no pressure and no vacuum evident. Dare I say it, it may be fixed. It certainly appears that I pinched a vent line when I dropped my tank 2 to 3 months ago but the warm weather made it manifest itself. When I lowered the tank ALL symptoms disappeared. Hallelujah!
Click to expand...

After you park the Jeep for a bit-Can you smell gas at all?
LG
 
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