Fuel tank hose leakage - Diesel Forum - TheDieselStop.com
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post #1 of 7 (permalink) Old 04-25-2017, 02:25 PM Thread Starter
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Fuel tank hose leakage

Well. it's been awhile since I have addressed this forum but I have a problem that is a PITA to resolve.

I have a leak in my connection line to the selector switch for tank #1 of my fuel hose. The line is held in place by a plastic connector that slides over a nipple and held by a a clip that maintains the connection. Evidently, there is an o-ring in the connector that is secured via this clip and it prevents any fuel leakage once applied.

When the line is disconnected, fuel continues to flow out of this hose preventing any insight as to how to replace this o-ring. If there is one there?

Anyone had any experience with this or should I just cut the connector out and go directly to the nipple with a clamp? I am worried about collapsing the nipple as it is made of plastic. Your thoughts appreciated. Thank you.

1994 F250 HD, IDI Diesel, 3:55 gears, K&N filter, Hayden Tranny Cooler, Monroe HD SensaTrac shocks, dual pillar pod with temp & tranny guage, poly fuel tanks,aluminum racing radiator
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post #2 of 7 (permalink) Old 04-26-2017, 01:47 PM
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...the selector switch for tank #1...
The switch is on the dash - you're talking about the selector VALVE on the frame rail.
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The line is held in place by a plastic connector that slides over a nipple and held by a a clip that maintains the connection.
'92-up gassers use stainless steel quick connects - I'm surprised that diesels still used the older plastic ones in '94. Click this & read the caption:

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When the line is disconnected, fuel continues to flow out of this hose...
Remove & replace the filler cap to vent the tank pressure. Put a catch-pan under the hose end, and once enough fuel drains to create a slight vacuum in the tank, it should slow or stop. Or you could unclip the other end from the tank, and pull the whole line assembly out of the truck to work on.
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...should I just cut the connector out...?
NO! Never cut the fuel lines, and never attempt to clamp them. They're hard nylon, so they don't need clamps to seal onto a proper barb. They do NOT fit the quick-connect nipples of the valve, so don't attempt to do that, either. If the line is damaged, the proper repair is to either put a new quick-connect on (if it's still long enough), or to splice it. But hard nylon lines simply slip (forcibly) over their barbs - no clamps.



If you're right about the O-ring (which would be surprising), then you can carefully pick the damaged one(s) out, IF you can find the correct (fuel-proof) replacement O-ring(s). Use clean motor oil ONLY to lubricate all the O-rings before reinstalling on the cleaned nipples. You should really clean everything BEFORE disconnecting anything.


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post #3 of 7 (permalink) Old 04-26-2017, 05:12 PM Thread Starter
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Steve -

Thank you for the response, I was about to give up. Yes, I am talking about the selector valve that goes to my tank#1. The fuel lines are not plastic, but a vinyl
covered metal flex tubing and the illustration you show doesn't quite match but is close. I believe it shows where the outlet side of the valve is is located. No big deal but it does show the clips, etc.

First I am going to open the fuel cap to prevent the siphoning action and than remove the fuel line from the valve assembly. If condition allow, I can than get a good look
at the o-ring and see if it can be removed. I have a good supply of all sizes. If I can't get to it, I going to put a second 0-ring in on top of the old and reconnect. Check it out in a few days.

If I had to replace the switch, I wouldn't know where to look, I do have the extra room for replacement.

If all fails, I'll have to get more creative. Thanks again for your response!

1994 F250 HD, IDI Diesel, 3:55 gears, K&N filter, Hayden Tranny Cooler, Monroe HD SensaTrac shocks, dual pillar pod with temp & tranny guage, poly fuel tanks,aluminum racing radiator
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post #4 of 7 (permalink) Old 04-29-2017, 07:03 AM Thread Starter
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Well, this 80 year old body is still able to slide around under the truck, its been awhile. So far I have disconnected both the fuel lines and they are draining in a bucket.

My question is - that some years back these fuel line were disconnected to install a new fuel tank and I wonder if they were crossed in the installation. I know that one line is 3/8 and the other is 5/16. The lines are color coded so is it possible they are attached to the wrong fitting on the valve? Currently the blue line is going to the connection on the inside of the rail, The second line (grey) is going to the connection on the outside of the rail. Does anyone have a diagram showing which line is going where? (blue vs. grey) Thank you again for any responses.

1994 F250 HD, IDI Diesel, 3:55 gears, K&N filter, Hayden Tranny Cooler, Monroe HD SensaTrac shocks, dual pillar pod with temp & tranny guage, poly fuel tanks,aluminum racing radiator
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post #5 of 7 (permalink) Old 04-30-2017, 01:05 AM
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Quote:
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...open the fuel cap to prevent the siphoning action...
It's not siphon action; it's vapor pressure in the tank pushing fuel out.
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I have a good supply of all sizes.
Size isn't the issue; there are many types of rubber used to make O-rings, and not all types are fuelproof.
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...put a second 0-ring in on top of the old and reconnect.
Bad idea.
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... this 80 year old body is still able to slide around under the truck...
This isn't cheap, but it's effective:


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Does anyone have a diagram showing which line is going where? (blue vs. grey)
I never found a good Ford diagram, so I made my own. But it's for GASSERS:



Yours should be very similar to the '87-89 dual. My diagram uses colors to indicate pressure, but Ford actually used blue for the supply lines coming from the tanks.


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Last edited by Steve83; 04-30-2017 at 01:14 AM.
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post #6 of 7 (permalink) Old 04-30-2017, 11:15 AM Thread Starter
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The problem has been resolved. I checked with a local diesel mechanic and he said that you can push all day long and they will not seat unless you hear a click. That's when the ridge of the connecting nipple has seated behind the 0'ring inside the connector. I had to twist the fuel line to get it into positioned and than push after you feel /hear the click. Worked for me.

1994 F250 HD, IDI Diesel, 3:55 gears, K&N filter, Hayden Tranny Cooler, Monroe HD SensaTrac shocks, dual pillar pod with temp & tranny guage, poly fuel tanks,aluminum racing radiator

Last edited by caseyj; 05-01-2017 at 03:09 PM.
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post #7 of 7 (permalink) Old 05-01-2017, 08:48 AM
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...and it was....
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