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post #1 of (permalink) Old 06-09-2000, 11:24 PM
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Bubbly Fuel

Now that my Jeep has run for a week its not getting fuel. I have a clear inline filter before the engine mounted pump. The fuel coming into there has little air bubbles in it. I pulled the element thinking it was clogged and the cause of my problem. Cranked it over and still see small air bubbles in the empty clear casing. It will idle okay but can't drive it due to fuel starvation. My diagnosis is clogged fuel from the tank. Tank is new. Sending unit is new. Engine mounted fuel pump is new. No electric pump. Is my diagnosis correct? Any tricks to clean the line or just replace it all the way from the tank to the pump? Thanks for the help.

Can you fix it?
I got a welder and a grinder. Heck yeah I can fix it.[img]/wwwthreads_images/icons/cool.gif[/img]
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post #2 of (permalink) Old 06-09-2000, 11:33 PM
 
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Re: Bubbly Fuel

you could try some compressed air, blown back into teh tank, but whatevers clogging will come back to haunt you!

maybe a misrouted vent or something could cause the bubbles?



OzarkJeep
77 CJ5, in a bunch of sanded and primered pieces
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post #3 of (permalink) Old 06-09-2000, 11:41 PM
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Re: Bubbly Fuel

I was going to undo the fuel line from the tank and blow it out but I don't know where the clog is. I had originally thought this might be vapor lock but I left my gas cap off and that didn't solve the problem. Guess this would be a good excuse to go buy a compressor or get my york installed.

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post #4 of (permalink) Old 06-10-2000, 02:50 AM
 
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Re: Bubbly Fuel

Run as much of the fuel line in steel as you can.
Make sure you have the return hooked up correctly.

If you are seeing bubbles before the pump, you are drawing air into the line somewhere...
Tank pick up not having a seam soldered,
rubber hose allowing air to leak in,
Pinhole in the line somewhere,
ECT.

If the bubbles were after the fuel pump, I'd suspect the pump diaphragm also.

FYI,
It would take a pretty good amount of bubbles to starve your engine for fuel.
Take the fuel line off at the carb.
Attach a FUEL LINE (Not Vacuum Line) to the steel fuel line you disconnected from the carb.
Take the coil connector off the ignition coil so the engine can't start, and you don't get stray sparks.
Stick the fuel line to the bottom of a large glass jar, or clear gasoline safe container.
Ten seconds of cranking the engine should net you well over a pint of fuel in the container.
If you don't get good pumping action, and good pulsing fuel flow...
The tank or fuel lines are restricted, or the fuel pump is bad.

If you do get good volume and flow,
crank the engine again with the fuel line all the way to the bottom of the jar,
do you see bubbles coming out with the fuel?
If you don't get bubbles here, you probably don't have an air leak big enough to worry about.
(Always worry about Fuel leaks!)
If you do get bubbles, start looking for that air leak we talked about...

Let us know what you find!!
Aaron.

"I Have The Body Of A God... Buddha"
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post #5 of (permalink) Old 06-10-2000, 08:09 AM
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Re: Bubbly Fuel

[img]/wwwthreads_images/icons/tongue.gif[/img] Take it from the "Diesel Doctor", bubbles in the fuel after the pump are an indication....EXACTLY as Aaron mentioned...that there is a pinhole leak in the fuel supply line from the tank. Often, a vehicle will run OK with a small pinhole until it gets in high altitude, OR the strainer begins to get clogged, creating a bit more fuel pump suction, which then draws more air into the line through the pinhole, causing a vapor lock condition. Also, Don,....you should be running the third fuel line on this setup.....I'm pretty sure that '77 had it......the third line which is a tank return line enables the fuel pump to pump a larger quantity of fuel IN A CIRCLE past the front filter. By using the three-port filter ahead of the carb, and by rolling the filter so the third line is up high, it automatically catches the bubbles and sends them back to the tank. Almost all Diesels pump fuel in a circle, and the auto guys finally realized how much sense it made and began doing it in the seventies. If you need details I can elaborate.[img]/wwwthreads_images/icons/smile.gif[/img]

CJDave
Quadra-Trac modified by the crack moonguy[img]/wwwthreads_images/icons/wink.gif[/img][img]/wwwthreads_images/icons/smile.gif[/img][img]/wwwthreads_images/icons/tongue.gif[/img] transfer case team.
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post #6 of (permalink) Old 06-10-2000, 08:14 AM
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Re: Bubbly Fuel

[img]/wwwthreads_images/icons/smile.gif[/img] Just think, Don......you would have to pay BIG BUCKS to go to mechanic skool in order to learn just what this Jeep has taught you in the last six months[img]/wwwthreads_images/icons/smile.gif[/img]

CJDave
Quadra-Trac modified by the crack moonguy[img]/wwwthreads_images/icons/wink.gif[/img][img]/wwwthreads_images/icons/smile.gif[/img][img]/wwwthreads_images/icons/tongue.gif[/img] transfer case team.
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post #7 of (permalink) Old 06-10-2000, 08:28 AM
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Re: Bubbly Fuel

Yes I have the third fuel line or second in my case (no charcoal canister). The return comes out of the side of the after pump filter and it is facing straight up. My problem started gradually and became so bad within 10 to 20 miles I was scared to drive it back to work. It first started surging above 45 mph while trying to accelerate. I got off the gas and it mosstly went away but I had to keep a light foot the rest of the way home. I drove to PT the next morning no problem. Returning home it almost stalled out while accelerating uphill at about 40-45 mph. Went to work and as long as I didn't get on it at all it got continue to run. On the way home for lunch it continually stalled with even the slightest pressure on the gas pedal. I pulled over once during these surges to almost stall and the bubbles were large and creating an air pocket in the filter. At lunch I popped the element out of the filter and cranked it up and the bubbles were very tiny. I did not attempt to drive it because I didn't want to have to walk half way to work. I'm out the door now to test it without an element in the filter. This has happened before when the filter was clogged but the immediately changed when the filter was replaced. I'll keep you posted on the outcome. Thanks a bunch for the help. A couple old hands and a pooh-bah.

Can you fix it?
I got a welder and a grinder. Heck yeah I can fix it.[img]/wwwthreads_images/icons/cool.gif[/img]
post #8 of (permalink) Old 06-10-2000, 02:00 PM
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Re: Bubbly Fuel

Fixed it. Shook the filter and produced bubbles. Shook it enough to get it to leak. Replaced the element and little rubber washers, took out the plastic adapters that the hose clamps to and repolaced the thread tape. No more bubbles but can't go test drive because of the thunderstorm. Thanks for all the help. One day I'll learn to eliminate the "hey stupid" stuff before I seek help.

Can you fix it?
I got a welder and a grinder. Heck yeah I can fix it.[img]/wwwthreads_images/icons/cool.gif[/img]
post #9 of (permalink) Old 06-10-2000, 06:22 PM
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Re: Bubbly Fuel

[img]/wwwthreads_images/icons/crazy.gif[/img] Don.....my moonguys[img]/wwwthreads_images/icons/tongue.gif[/img][img]/wwwthreads_images/icons/tongue.gif[/img]don't think that was the cause. They still think it is a pinhole in the suction line and they want to know if you have a return line setup on that Jeep?[img]/wwwthreads_images/icons/crazy.gif[/img]

CJDave
Quadra-Trac modified by the crack moonguy[img]/wwwthreads_images/icons/wink.gif[/img][img]/wwwthreads_images/icons/smile.gif[/img][img]/wwwthreads_images/icons/tongue.gif[/img] transfer case team.
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post #10 of (permalink) Old 06-11-2000, 06:27 AM
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Re: Bubbly Fuel

I agree with Dave.
I had the same problem as you, turned out to be a pinhole in the line. Started out so small that there were no tell tale spots on the ground, it sort of just seeped onto the top of the gas tank ledge. I could smell gas but couldn't find the hole. It'll just get worse and then you won't get fuel to the carb and you will see a puddle.
Take a good look at the line running to the fuel pump so you won't get stranded somewhere.

CTjeepnut

Funny thing is, the more I practice, the luckier I get
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