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post #1 of (permalink) Old 06-16-2004, 12:00 PM Thread Starter
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Fuel Tank Sending Unit ?

I am trying to get my new fuel system put together and I have run into a snag.

I have my fuel tank: It is a plastic 20 Gal. tank from a 91 YJ, and it is in perfect shape. It has a sending unit in it, that has the in tank fuel pump. The pump still worked when I pulled the tank.

What I want is to get a new sending unit that does NOT have a pump. This tank will be feeding a SBC with a carb.

I was hoping to use a sending unit from an 87-90 YJ with a 258. However I have gone to three different parts places in my area, and all three of them told me they do not have that part. There was no listing at all, at any of the stores.
I did find out that a CJ sending unit will not work, because the YJs have a different shape hole in the tank where the sender attaches. (too bad, cause it is a lot easier to get a sending unit for a CJ)

I also got some information about Jeep using different fuel tanks starting in the model year 1991. But none of the parts people I talked to could tell me if the sending units from 87-90 have the same size mounting hole in the tank as the later tanks.

Pretty much the bottom line is that I am a lot more confused now, than I was when I started.

I would like to NOT have to deal with the dealership, but if worse comes to worse I will take my sending unit (with the pump) to the dealership and see if it matches up with the one for the 87-90. I am sure it will be expencive. If they don't match, I am really going to be stuck.

I am hoping that maybe someone has done this before, and may be able to give me a tip as to what to look for.

Thanks for any help, and sorry for the long post.

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post #2 of (permalink) Old 06-16-2004, 12:31 PM
 
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Re: Fuel Tank Sending Unit ?

Can't you get an auto meter gauge that is set up to use a crysler sender? I know some one that is using his factory yj 4 banger electronic in tank fuel pump feeding his amc 360. He runs a fuel pressure regulator mounted right next to his drivers seat and will turn it up to the point where the engine almost dies when he's on a steep climb where his motor would usually stall out. '87-90 tanks are very different than '91-95 tanks as far as shape goes. If you still want that sending unit take the time to open up your 4wd hard ware catalog it's listed right in there.
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post #3 of (permalink) Old 06-16-2004, 01:25 PM
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Re: Fuel Tank Sending Unit ?

Can't you remove the pump from the sender you have and fab a pickup tube?
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post #4 of (permalink) Old 06-16-2004, 01:41 PM Thread Starter
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Re: Fuel Tank Sending Unit ?

Andy, You make an exellent point. I could use the sending unit I have, along with a pressure reducing valve. Using the block mounted fuel pump and a standard fuel pick up unit is attractive to me because I would like to keep the finished product as simple as possible. (K.I.S.S.)
It is ironic that in order to keep it simple for later I am going through such a run around now.
If I should find out that an 87-90 sending unit will work in the tank I will put in the call to 4 wheel drive.
I am not too worried about the guage. I figure that what ever I go with, I will be able to get a guage that works.

I will not rule out running with my electric fuel pump, and a reducing vavle.
And the Idea of being able to change the fuel pressure is interesting.
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post #5 of (permalink) Old 06-17-2004, 08:03 AM Thread Starter
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Re: Fuel Tank Sending Unit ?

Jim,
After reading your post I spent some time looking at the unit I have, I feel a little silly [img]images/graemlins/blush.gif[/img] that I didn't think of that.
It seems to me that as long as there is not a check valve in the return line, I can removed the electric pump, and use what used to be the supply connection for the return line (because without the pump on there the line will end half way up the tank) I can use the old return line as my supply feed.

One issue I could come up agenst is having a non working guage. When the tank and sending unit came out of the Jeep the Fuel gauge didn't really work. I suspect that the problem was the guage itself. I think a quick check with the amp meter should tell me if the resistanc still varies.

Thanks for the tip Jim

Can anyone tell me off the top of their heads if there are check valves that in ether the supply or return that will need to be removed.
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post #6 of (permalink) Old 06-17-2004, 09:41 AM
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Re: Fuel Tank Sending Unit ?

On my '78 the return line is smaller than the supply line; be sure to check on that.

On the subject of the gauge, those instruments are pretty reliable. Before you condemn it be sure that the wiring is in good shape. The sending unit must have a good, clean ground. All of the connections have to be clean because any additional resistance will screw up the gauge. And the gauge must have good voltage at the input. You could well replace the gauge and find that you haven't solved the problem.

When I started the restoration the gauge hadn't worked for years. I put off doing the instruments and got the Jeep driveabla and, surprise, the gauge worked fine. I think that the culprit was a rusty connection where the ground wire from the sending unit was screwed to the frame.

I don't think that there are any check valves in the system, but can't say for sure. But the return line usually doesn't go to the bottom of the tank; does it on your sender?

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post #7 of (permalink) Old 06-17-2004, 11:55 AM Thread Starter
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Re: Fuel Tank Sending Unit ?

Jim, I thank you again for the help.
The sending unit I have has a return that does go all the way to the bottom of the tank. I did not look carefully enough to notice if the return line was any smaller.
The more I think about it the better the idea seems. If the return line is of equal size, I am going to move ahead with my gas tank install, and I am going to be money ahead, because I won't have to buy a new sender.
Thanks a bunch [img]images/graemlins/40BEER.gif[/img]
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post #8 of (permalink) Old 06-18-2004, 11:25 AM Thread Starter
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Re: Fuel Tank Sending Unit ?

UPDATE !!

It looks as though this is going to work. The return line is in fact smaller than the supply line... But the supply line is HUGE.
I had been planning on running 5/16" Fuel line, and taht is what the return line is. So it seems to me like I should be fine. I will just have to add a fitting to increse the size of the "new" return line where it enters the tank.

I would think that 5/16" should be fine for feeding a 350. Does anyone think that it will be too small? (the motor will probably never see any higher than 4500 RPM.

Thanks for the help and the Great Idea. Not the first time this board has saved me healthy chunk of change. [img]images/graemlins/smile.gif[/img]
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post #9 of (permalink) Old 06-18-2004, 07:21 PM
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Re: Fuel Tank Sending Unit ?

</font><blockquote><font class="small">In reply to:</font><hr />
I would think that 5/16" should be fine for feeding a 350. Does anyone think that it will be too small? (the motor will probably never see any higher than 4500 RPM.

[/ QUOTE ] 1. 5/16" should be fine.
2. Keep the larger return diameter line,
3. 3/8" is great,
4. It's large enough,
5. To not have line resistance,
6. Overwhelm the regulator.
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post #10 of (permalink) Old 06-27-2004, 09:52 PM
 
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Re: Fuel Tank Sending Unit ?

Chevy 350 / Truck Avenger 670 cfm carb.

I use 3/8 rubber hose for both fuel lines.

One thing I did that I was glad, was put on two fuel filters on both lines.

Gas Line.

One before the pump.
One after the pump.

Return Line:
One right after the fuel pump return line
One right before going back into the tank.

Helps keep everything clean.







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