adding second tank
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Mountain Pass
Joined: Mar 2003
Posts: 124
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From: Up state NY
adding second tank
What is i used both tanks out of the 89. and took out my machenical fuel pump, would the electric pumps move the fuel with enough pressure or would there be to much prussure. That way i could just use everything out of the other truck to hook up the tanks.
Senior User
Joined: Oct 2002
Posts: 230
Likes: 1
adding second tank
Originally posted by franklin2
He said on a boat, they have extra tanks, and they are hooked to a transfer pump. When the main tank goes dry, they just turn on the transfer pump and it fills the main tank back up.
He said on a boat, they have extra tanks, and they are hooked to a transfer pump. When the main tank goes dry, they just turn on the transfer pump and it fills the main tank back up.
Moderator
Joined: Jan 2001
Posts: 56,993
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From: Virginia
adding second tank
"What is i used both tanks out of the 89. and took out my machenical fuel pump, would the electric pumps move the fuel with enough pressure or would there be to much prussure. That way i could just use everything out of the other truck to hook up the tanks."
If you ran the stock fuel injection pumps, you would have to have a return line to each tank. And the system on the 89 is set-up for about 40 psi, way too much for a carb which only needs about 5 psi.
If you ran the stock fuel injection pumps, you would have to have a return line to each tank. And the system on the 89 is set-up for about 40 psi, way too much for a carb which only needs about 5 psi.
Thread Starter
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Mountain Pass
Joined: Mar 2003
Posts: 124
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From: Up state NY
adding second tank
[QUOTE]Originally posted by steve83
[B]With nothing but a T between them, fuel could flow back & forth. If you parked on a hill that positioned the bottom of the higher tank above the vent port or the filler neck of the lower tank,
i don't understand why this would happen the fuel would flow to the motor not from tank to tank.
[B]With nothing but a T between them, fuel could flow back & forth. If you parked on a hill that positioned the bottom of the higher tank above the vent port or the filler neck of the lower tank,
i don't understand why this would happen the fuel would flow to the motor not from tank to tank.
Thread Starter
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Mountain Pass
Joined: Mar 2003
Posts: 124
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From: Up state NY
adding second tank
I read a freightliner manual today that showed a duel tank setup on a tractor trailer. there was on sendind unit in one tank and a supply line to the second tank.They showed the line going into a "t" and spliting to both tanks and it said it would draw off the lowest tank (switching back and forth) the second digram showed that the motor drew off the first tank and as it would get low it would draw fuel out of the second tank into the first ,and it said nothing about flow back and forth between tanks because of osmosis. i don't think that there would be enough pull between the tanks to move the fuel.
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Joined: Jan 2001
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From: Virginia
adding second tank
I agree with steve for his reasons of not doing it that way, but I was wondering if you did do the "tee" thing, are you going to pull both tanks, and solder or braze a fitting in the bottom of each tank? That's the only way that it would work if you want a gravity fed system. You have to rememeber the original set-up has the hole on the TOP of each tank. Yea you may get a siphon action going, and the fuel would run up and over, but as soon as one tank got a little low, and you went around a turn, and you lost the siphon, then you have air in the line. The pump probably wouldn't pull fuel from either tank if there was air in the fuel line.
Post Fiend
Joined: Jan 2000
Posts: 5,330
Likes: 17
From: Dryden, ON, Canada
adding second tank
An 89 has the dual(or triple) pump setup, with a low pressure in tank pump and framerail mounted high pressure.
Your best option would be to get a sending unit for an 85-86 F-Series with a 300 or 351w for the rear tank, as they used a mechanical pump and the large sender opening. However, you still wouldn't have a functioning guage on the rear tank no matter how you wired it, even if you got the proper chassis harness for a truck with dual tanks and installed all the factory switchgear.
Evan
Your best option would be to get a sending unit for an 85-86 F-Series with a 300 or 351w for the rear tank, as they used a mechanical pump and the large sender opening. However, you still wouldn't have a functioning guage on the rear tank no matter how you wired it, even if you got the proper chassis harness for a truck with dual tanks and installed all the factory switchgear.
Evan
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Mountain Pass
Joined: Mar 2003
Posts: 124
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From: Up state NY
adding second tank
[QUOTE]Originally posted by franklin2
I was wondering if you did do the "tee" thing, are you going to pull both tanks, and solder or braze a fitting in the bottom of each tank? That's the only way that it would work if you want a gravity fed system.
i'm not using a gravity feed system i'm using the machenical pump at the motor to draw the fuel. Yes the pipe does come out the top but it goes just about all the way to the bottom.(not all the way because it would draw dirt)
I also have the dash switch in the heater comtrol, but napa said that the switching valve was 50 bucks.I can hook up the switch and use it to change which tank the guage is reading from.
I was wondering if you did do the "tee" thing, are you going to pull both tanks, and solder or braze a fitting in the bottom of each tank? That's the only way that it would work if you want a gravity fed system.
i'm not using a gravity feed system i'm using the machenical pump at the motor to draw the fuel. Yes the pipe does come out the top but it goes just about all the way to the bottom.(not all the way because it would draw dirt)
I also have the dash switch in the heater comtrol, but napa said that the switching valve was 50 bucks.I can hook up the switch and use it to change which tank the guage is reading from.
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Post Fiend
Joined: Nov 2002
Posts: 9,987
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From: Memphis, TN
adding second tank
Originally posted by steve83
FYI You can't use the unpowered switching valve from an '84-90 EFI because it operates from the pressure of the in-tank pump, and you don't have one.
FYI You can't use the unpowered switching valve from an '84-90 EFI because it operates from the pressure of the in-tank pump, and you don't have one.
