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Old 04-13-2011, 07:09 AM   #1
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New fuel tank - Am I missing something?

I'm in the process of installing a small day tank (19 gal). I was planning on having the return line from the engine go to that tank (it was previously going to one of the old original tanks that I removed last fall;, the PO installed new tanks but left the return line to its original tank, not sure I understand the logic but that's another story).

It looks like I'm missing an outlet for the return line (one for the fill, one vent and one feeding the engine). Any suggestions? There is no outlet for a return line on the large tanks either.

*


-- Edited by Fotoman on Wednesday 13th of April 2011 07:12:16 AM
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Old 04-13-2011, 07:27 AM   #2
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RE: New fuel tank - Am I missing something?

Fotoman

If I recall, you have a Lehman 120 engine, as I do.

Dont even worry or think about the return line. The Lehman 120 returns 1/2 pt of fuel for every 10 hours of running.

Leave the return line as it is and dont worry about it. This is one engine where you can have the return line to only one tank and it doesnt matter.\

R.
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Old 04-13-2011, 08:26 AM   #3
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RE: New fuel tank - Am I missing something?

You're right, I have a FL 120. But my problem is right now the return line doesn't go anywhere anymore since I removed the old tanks. I know the return flow is minimal, but I have to route it somewhere.
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Old 04-13-2011, 08:33 AM   #4
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RE: New fuel tank - Am I missing something?

Quote:
Fotoman wrote:
You're right, I have a FL 120. But my problem is right now the return line doesn't go anywhere anymore since I removed the old tanks. I know the return flow is minimal, but I have to route it somewhere.
*Why not just T or Y it into the fill line.**That will just relieve any back*pressure on the injection pump if there is any at all.

*
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Old 04-13-2011, 08:35 AM   #5
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RE: New fuel tank - Am I missing something?

That's kindda of what I was thinking about, just not sure how to do it.
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Old 04-13-2011, 09:01 AM   #6
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New fuel tank - Am I missing something?

Quote:
JD wrote:Fotoman wrote:
You're right, I have a FL 120. But my problem is right now the return line doesn't go anywhere anymore since I removed the old tanks. I know the return flow is minimal, but I have to route it somewhere.
*Why not just T or Y it into the fill line.**That will just relieve any back*pressure on the injection pump if there is any at all.

*

*NOT good !!

If the return line leak off off tube on top of the injectors is not properly seated, you could be introducing fuel leakage into the engine oil system on top of the injectors !

See part 209 on page A20 of the Base Engine Manual for the Lehman.

Be safe about this. Run the return line to any tank you can, even the day tank would be OK. But be sure the return line does not have any pressure to it.

R.

*


-- Edited by ralphyost on Wednesday 13th of April 2011 09:03:55 AM
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Old 04-13-2011, 09:12 AM   #7
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RE: New fuel tank - Am I missing something?

Not sure we are talking about the same thing here. I meant I was thinking about hooking the return to the hose that will fill the day tank (I will install a small 12v pump to get the fuel from the main tanks). Just not sure about the fittings I should use. Or is there a way to add an outlet on my tank?
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Old 04-13-2011, 09:25 AM   #8
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RE: New fuel tank - Am I missing something?

Quote:
ralphyost wrote:JD wrote:not just T or Y it into the fill line.**That will just relieve any back*pressure on the injection pump if there is any at all.

NOT good !!

If the return line leak off off tube on top of the injectors is not properly seated, you could be introducing fuel leakage into the engine oil system on top of the injectors !

See part 209 on page A20 of the Base Engine Manual for the Lehman.

Be safe about this. Run the return line to any tank you can, even the day tank would be OK. But be sure the return line does not have any pressure to it.

R.
-- Edited by ralphyost on Wednesday 13th of April 2011 09:03:55 AM

*Ralph,

The fill line we are talking about is the tank fill not the injector pump pick up.

I'm not sure where the pressue would come from to the injectors.* There is no pressure on the tank fuel*fill line for either the main tank or the day tank even when taking on fuel it is vented to the atmosphere.* Any fuel in the return line would just dribble down the fill line into the day tank.

Am I missing something here?*
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Old 04-13-2011, 10:52 AM   #9
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RE: New fuel tank - Am I missing something?

Why not drill/tap into the top of the tank? It will hold a 1/4 npt fitting for the return line I'm sure. Keep it simple.
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Old 04-13-2011, 11:14 AM   #10
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RE: New fuel tank - Am I missing something?

"The fill line we are talking about is the tank fill not the injector pump pick up."

*

Ah yes, now I read it correctly.

I apologize !

thanks

R,.
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Old 04-13-2011, 12:06 PM   #11
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RE: New fuel tank - Am I missing something?

Quote:
jleonard wrote:
Why not drill/tap into the top of the tank? It will hold a 1/4 npt fitting for the return line I'm sure. Keep it simple.
*Yes, that's what I would like to do. Just not sure where to get the fitting and wasn't sure I could add something like that to the tank without compromising its integrity.

*
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Old 04-13-2011, 12:36 PM   #12
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RE: New fuel tank - Am I missing something?

You can get a simple brass barbed fitting at cheapo-depot and clamp the hose to it. There is no pressure on the return to speak of.

Another thought is that you could add a T to the fuel vent provision at the tank, and return the fuel to the T and into the tank. That way you would not have to tap the plastic (which is no big deal).
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Old 04-13-2011, 02:43 PM   #13
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RE: New fuel tank - Am I missing something?

One more suggestion.* Remove the sending unit.* Drill a hole near the sending unit that you can reach from the inside of the tank through the sending unit hole.* Then put a threaded 90* barb fitting through the hole with a soft fuel proof*washer and nut on both the outside and the inside of the tank.* From the inside it would be threads, nylon nut, AL washer, fuel proof soft washer, tank body, then outside,*fuel proof washer, AL washer, nylon nut and the 90* barb fitting.* Tighten the two nylon nuts against each other sealing the hole in the tank with the fuel proof washers.* Reinstall the sending unit.

It took longer to explain than it would to do.
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Old 04-14-2011, 05:07 AM   #14
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RE: New fuel tank - Am I missing something?

Fotoman, on my Lehman 120 set-up, the return line just goes back to the primary filter. Very simple foolproof arrangement. You could maybe do that with a simple T junction in the fuel-line just before it enters that filter...? My filter has a second entry point, but the above would effectively be the same, as Ralph rightly says, we are not talking about high flows on these things.
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Old 04-14-2011, 07:14 AM   #15
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RE: New fuel tank - Am I missing something?

Peter, I will explore that idea. For all I know maybe my primary filter has a second entry point...

Thanks JD for the instructions. If I can't tap into the primary filter I might just add what I need on the tank.
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Old 04-14-2011, 10:06 AM   #16
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RE: New fuel tank - Am I missing something?

I see*return lines*Tee's in to*the vent line near the tanks.
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Old 04-14-2011, 01:53 PM   #17
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New fuel tank - Am I missing something?

Quote:
Fotoman wrote:
Not sure we are talking about the same thing here. I meant I was thinking about hooking the return to the hose that will fill the day tank (I will install a small 12v pump to get the fuel from the main tanks). Just not sure about the fittings I should use. Or is there a way to add an outlet on my tank?
******** Fotoman,* I believe there is an optional sender unit for diesels by Moellar Marine that will replace your sender and have a tap for a return line in the plate at the top of the unit.* Part number 35724-10.* Cross-linked poly tanks can also be purchased for diesel application with the return inlets installed at the factory.

JohnP

*



-- Edited by JohnP on Thursday 14th of April 2011 02:00:35 PM


-- Edited by JohnP on Thursday 14th of April 2011 02:03:31 PM
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Old 04-15-2011, 07:15 AM   #18
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RE: New fuel tank - Am I missing something?

John, that's great. I could probably remove the actual sender unit and drill a hole myself to add a return line inlet. Food for thoughts.
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Old 04-15-2011, 09:03 AM   #19
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New fuel tank - Am I missing something?

Quote:
Fotoman wrote:
John, that's great. I could probably remove the actual sender unit and drill a hole myself to add a return line inlet. Food for thoughts.
*********That is what I was thinking,** but now that I realize this is a day tank and will be filled by a pump, perhaps the tee arrangement on the fill neck might be easier in the long run.**

How much fuel do you burn in a day?** 10hours at 2gph- you have ran out! Or will the refilling be automatic by a switch on the dash?

*JohnP

*



-- Edited by JohnP on Friday 15th of April 2011 09:06:08 AM


-- Edited by JohnP on Friday 15th of April 2011 09:08:01 AM
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Old 04-15-2011, 09:12 AM   #20
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RE: New fuel tank - Am I missing something?

On a weekend I typically run the engine 1-2 hours a day. Not a lot. The only time I will use the engine more intensively is during my vacation. The tank holds 19 gallons so I'm ok for a complete day. I will set up the system with a gauge and a switch by the helm to fill the tank on the fly.
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