cjmark
Contributor
Posts: 19 
First Name: Mark
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Post by cjmark on Nov 20, 2017 20:37:01 GMT -5
Is it normal to have air bubbles in fuel pump filter/site glass? No leaks, starts and run fine. Expect problems down the road?
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Post by Scoutpilot on Nov 21, 2017 5:28:52 GMT -5
Bubbles in the glass mean that at some point(s) in the fuel line from the tank, air is leaking IN. Inspect the tubing, Check all connections for tightness. Check the rubber for minute cracks on the outside by bending it. I would suspect the rubber first.
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oilleaker1
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Post by oilleaker1 on Nov 21, 2017 7:18:44 GMT -5
I'll add that the gasket under the glass bowl can leak and cause bubbles also. Even if fuel isn't leaking! Oilly
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cjmark
Contributor
Posts: 19
First Name: Mark
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Post by cjmark on Nov 21, 2017 21:21:49 GMT -5
Dang! Thought more gas in tank, put in 5 gallons, no more bubbles. I should of known picking up air.
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Post by Scoutpilot on Nov 22, 2017 5:42:33 GMT -5
Well durn it son! Ya'll just cain’t be runnin’ aroun' near empty. Gotta tell us this stuff. I’ve been chastised before for asking the really simple question, “Uhh. Got gas?”
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cjmark
Contributor
Posts: 19
First Name: Mark
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Post by cjmark on Nov 22, 2017 9:49:35 GMT -5
Yep, felt a rookie when I realized it. Like so many problems with these old Jeeps, something simple to fix. Had tank out recently, only a gallon or so of gas on hand, 2 mile test drive then inspection. Oh well, thanks for advice.
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Post by Scoutpilot on Nov 22, 2017 11:55:02 GMT -5
Don’t feel bad. I regularly run out of gas when I’m testing carbs on the road.
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Post by schimms15 on Nov 22, 2017 11:56:26 GMT -5
most of us keep a stick under the seat to check the fuel level, dont feel bad I have had to use a tree branch on the side of the road once.
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cjmark
Contributor
Posts: 19
First Name: Mark
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Post by cjmark on Nov 22, 2017 23:47:21 GMT -5
I’m just going to chalk this post up as one of my more memorial ones. And a test of video posting  Most of us can chuckle because we can relate. |
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Deleted
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Post by Deleted on Dec 9, 2017 22:55:44 GMT -5
Just how low was the fuel in the tank ?, are you sure it was "Sucking Air" ?...... the responses before you added fuel were spot on, and I will add it's common for the fitting on the suction side of the pump to leak on a low tank of fuel. Why you ask!, it's a pot metal casting with a brass fitting screwed into it, and a tapered (NPT) pipe thread to boot, in time the pot metal stretches, I've seldom removed a fuel pump and fount this fitting tight in the pot metal casting. Now, on a full tank of fuel, the pump really doesent Suck anything, as the tank is somewhat above the pump, if you take the fuel line off before the pump (on a full tank) fuel will run out (on level ground), as the fuel is used the pump progressively needs to Suck (pull fuel) to feed the engine and there will be a slight vaccume on the inlet side of the pump!, at this point IF there is a leak on the Glass bowl gasket/fitting on the suction side of pump/rubber fuel line/or deteriorated metal line to tank (also do NOT use worm gear clamps on the suction side, use the spring band style clamp you squeeze with pliers) you WILL see bubbles in the fuel pump bowl. Now, you asked "Will there be troubles down the road"...... That depends  If you were running out of fuel and it was indeed sucking air, NO!...... If you were experiencing what I mentioned in the above paragraph YES. Why you ask!.... on my trips to the mountains I have seen this on every trip, bubbles in the fuel pump bowl, on lower elevations it's probably not going to bother, but in time will eventually bite you in the butt. Anyway, in the mountains the troubles get worse with altitude/heat/and grades. I'll use Imogene pass as an example (I was there this past August with 15-18 Jeeps) the climb is many miles and very steep in places and ends up at 13,100 feet. Nobody had trouble till we climbed probably 2/3rds of the way up, at this point the steep switch backs start and your using power, power makes heat, and underhood temps are rising with the altitude. Also as the grade increases, the fuel pump also rises above the tank more so and increases the slight vaccume I mentioned earlier . So now your experiencing bubbles at 1/2 tank instead of 1/8 tank. Several Jeeps start experiencing the dreaded "Vapor Lock" at this point. In reality it's NOT vapor lock, it's one or several small leaks on the suction side of the fuel pump that are increased due to Heat (hoses and fittings/pot metal castings swelling up due to heat). So water is poared on the fuel pump to cool it, fuel is added to the tank, the Jeep starts and runs great for another mile till the altitude/heat/grades take there toll once again, if I'm explaining this correctly you will see a pattern forming here, this cycle continues till you either make the summit or are towed to it. I've thought about this at great length, I believe I am correct, as few if any ever have trouble going down hill where heat and the fact that the fuel tank is ALWAYS above the fuel pump (no slight vaccume). Anyway to test this, run your tank down to a gallon or two and jack up the front of the Jeep a couple feet or drive it into a ditch and get the front end way higher than the back end and see if you have bubbles in your fuel pump bowl. Sorry for being long winded, but this is a VERY common problem. Lee |
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oilleaker1
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Post by oilleaker1 on Dec 10, 2017 7:29:56 GMT -5
Good study Lee! You watched me cuss and discuss my '43 GPW with this very problem on Imogene Pass. I realized that I could put my hand on the fuel pump, it was not hot and vapor locked. Like a dumb bozo I should have simply backed my Jeep up the pass eh? Model T style.
To add to this study, a WW2 Jeep pulls fuel out of the tank and routes it clear over to the upper firewall on the passenger side, through a canister fuel filter, then down to the generator splash plate, around the front of the engine and into the fuel pump. That poor little pump which is the same as a CJ (almost) has to suck it much harder and farther. What saved me was the hand assist lever that pump has. It worked , every 200 feet or so. As Lee stated, going down hill wasn't a problem.
Mine began this poor fuel delivery at 10, 500 feet and got real bad at 12,000. I never knew I had this problem because where I live the highest peak is 7100.
"Come on down" for better fuel delivery! Oilly
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Deleted
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Post by Deleted on Dec 10, 2017 8:51:02 GMT -5
The mystery is "Why" do they never leak fuel, but Suck air ?...... I believe "Vapor Lock" is a byproduct of this syndrome, my cousins 3B suffered the most, poaring water on the fuel pump resulted in sizzling!, I'm sure at that point the check valves were in no condition to do their job, and the seams on the potmetal castings leaked as well. Testing at home is critical, charge the fuel line at the tank end with an electric fuel pump, you will be surprised what all leaks under pressure! Lee |
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Post by brucew on Dec 10, 2017 14:45:58 GMT -5
Just how low was the fuel in the tank ?, are you sure it was "Sucking Air" ?...... the responses before you added fuel were spot on, and I will add it's common for the fitting on the suction side of the pump to leak on a low tank of fuel. Why you ask!, it's a pot metal casting with a brass fitting screwed into it, and a tapered (NPT) pipe thread to boot, in time the pot metal stretches, I've seldom removed a fuel pump and fount this fitting tight in the pot metal casting. Now, on a full tank of fuel, the pump really doesent Suck anything, as the tank is somewhat above the pump, if you take the fuel line off before the pump (on a full tank) fuel will run out (on level ground), as the fuel is used the pump progressively needs to Suck (pull fuel) to feed the engine and there will be a slight vaccume on the inlet side of the pump!, at this point IF there is a leak on the Glass bowl gasket/fitting on the suction side of pump/rubber fuel line/or deteriorated metal line to tank (also do NOT use worm gear clamps on the suction side, use the spring band style clamp you squeeze with pliers) you WILL see bubbles in the fuel pump bowl. Now, you asked "Will there be troubles down the road"...... That depends If you were running out of fuel and it was indeed sucking air, NO!...... If you were experiencing what I mentioned in the above paragraph YES. Why you ask!.... on my trips to the mountains I have seen this on every trip, bubbles in the fuel pump bowl, on lower elevations it's probably not going to bother, but in time will eventually bite you in the butt. Anyway, in the mountains the troubles get worse with altitude/heat/and grades. I'll use Imogene pass as an example (I was there this past August with 15-18 Jeeps) the climb is many miles and very steep in places and ends up at 13,100 feet. Nobody had trouble till we climbed probably 2/3rds of the way up, at this point the steep switch backs start and your using power, power makes heat, and underhood temps are rising with the altitude. Also as the grade increases, the fuel pump also rises above the tank more so and increases the slight vaccume I mentioned earlier . So now your experiencing bubbles at 1/2 tank instead of 1/8 tank. Several Jeeps start experiencing the dreaded "Vapor Lock" at this point. In reality it's NOT vapor lock, it's one or several small leaks on the suction side of the fuel pump that are increased due to Heat (hoses and fittings/pot metal castings swelling up due to heat). So water is poared on the fuel pump to cool it, fuel is added to the tank, the Jeep starts and runs great for another mile till the altitude/heat/grades take there toll once again, if I'm explaining this correctly you will see a pattern forming here, this cycle continues till you either make the summit or are towed to it. I've thought about this at great length, I believe I am correct, as few if any ever have trouble going down hill where heat and the fact that the fuel tank is ALWAYS above the fuel pump (no slight vaccume). Anyway to test this, run your tank down to a gallon or two and jack up the front of the Jeep a couple feet or drive it into a ditch and get the front end way higher than the back end and see if you have bubbles in your fuel pump bowl. Sorry for being long winded, but this is a VERY common problem. Lee Very well put, Lee, I've been saying this for years. I hope you have better luck getting people to listen than I've had. One fellow on the FCT adamantly disagreed with me and insisted that an electric pump was the only thing that would solve his problem. I helped him install one, and when the switch was turned on, his fuel supply line from the tank to the pump became a sprinkler! B-dubya |
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Deleted
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Post by Deleted on Dec 10, 2017 17:59:20 GMT -5
Very well put, Lee, I've been saying this for years. I hope you have better luck getting people to listen than I've had. One fellow on the FCT adamantly disagreed with me and insisted that an electric pump was the only thing that would solve his problem. I helped him install one, and when the switch was turned on, his fuel supply line from the tank to the pump became a sprinkler!  B-dubya Few understand, most blame other issues. I'm trying to come up with a name for this issue like "Pump to Tank Ratio". Not sure if that's correct or not!. I'm willing to bet, of the Jeeps I run across here on the flatlands, 90% have bubbles in the fuel pump bowl!. Most do not understand that worm gear clamps of the 1/4"-5/16" size point load the fuel line and make it leak worse, or after one season you need to replace rubber fuel line as the fuel makes it hard and causes vaccume leaks. Lee |
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Post by Scoutpilot on Dec 10, 2017 20:13:56 GMT -5
Yeah. Most blame the carburetor for everything because they don’t understand how it works. For that matter, since everything is computer controlled these days many don’t understand how a motor is a Rube Goldberg setup where every part affects every other part in some way. Famous last words…”But I bought new old stock!!!”
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If you were running out of fuel and it was indeed sucking air, NO!...... If you were experiencing what I mentioned in the above paragraph YES. Why you ask!.... on my trips to the mountains I have seen this on every trip, bubbles in the fuel pump bowl, on lower elevations it's probably not going to bother, but in time will eventually bite you in the butt. Anyway, in the mountains the troubles get worse with altitude/heat/and grades. I'll use Imogene pass as an example (I was there this past August with 15-18 Jeeps) the climb is many miles and very steep in places and ends up at 13,100 feet. Nobody had trouble till we climbed probably 2/3rds of the way up, at this point the steep switch backs start and your using power, power makes heat, and underhood temps are rising with the altitude. Also as the grade increases, the fuel pump also rises above the tank more so and increases the slight vaccume I mentioned earlier 