88 with dual tanks, help please....

[this user name may change]

Thanks for the info AD, and sorry to hear about your injury, hope you can heal from it
SVT

what he said.....



id be helpful if you had a picture of what your talking about
what if you make it so that tank B is on a toggle switch and fills up tank A?........

 

[this user name may change]

anything?

 

[RangerSVT]

Like AD said, if you fill a tank you are not taking fuel from, pretty soon you will overfill that tank, and be dumping it on the ground....
SVT

 

[this user name may change]

so what parts do i need is what im asking.......

 

[RangerSVT]

the ENTIRE run of fuel lines, selector valve and complete
"Frame" wiring harness.
AD

short answer? a dual tank donor vehicle.
AD

Are you going factory, or are you just going to locate a switch in the dash??
SVT

 

[this user name may change]

switch in the dash i think

 

[this user name may change]

imo, this would have been helpful in your explanation... just saying....

 

[RangerSVT]

That diagram is close, but incorrect. The relay has to be a 5 pin, not a 4 pin. Pin 87 should go to one pump, and pin 87A (not pictured, but located in the middle of a 5 pin SPDT relay) will go to the other pump. This will allow power to switch from NO pin 87A to NC pin 87 when the coil has voltage applied. Depending on how the selector valve is designed, it will also be hooked to this relay. I have not seen the selector valve's electrical hookup, so I can't comment on that, but it should be a simple solenoid type valve, which would be hooked in with the relay...
SVT

 

[this user name may change]

many thanks
would the relay be under the hood or under the dash?
(the pic. is an spst, i only realized the mistake after posting)

 

[RangerSVT]

There are also 5 pin SPST relays, you have to be careful, you can't just grab a 5 pin relay...There should be a diagram on the relay itself, if a line is connecting 87 and 87A together, then its SPST, if the line is going between 87A and 30, then a dotted line to 87, then its a SPDT....As far as factory location of the relay, I would guess the firewall in the engine bay, but I wouldn't be surprised if I was incorrect. If you are making your own wiring harness for the dual tank setup, you can locate it where it is convenient for you...
SVT

 

[AllanD]

the issue is that without using the integrated valve that actually switches power to the in-tank pump as it mechanically switches the valve feeds there is no guarantee that the return fuel is being positively controlled.

And if you are trying to pump to the engine from one tank to run the engine and the return is headed to the other tank and that tank is full you can inadvertantly blow
3/4 of a tank of your expen$ive fuel overboard...

Not to mention potentially either blowing yourself up or dying horribly by being burned to death.

Is there something here that makes some of you NOT understand this?

having dual tanks is neat, it's nice, it's a damned cool cability to have, but if you do it wrong you can DIE, and worse you can take some innocent bystander(s) with you

There might not be a second chance to do it right

I have has a single failure, where the stem seal O-ring on one of the three way valves dies and pissed fuel into the electrical switch body, fortunatly it didn't ignite there, but
the fuel pressure blow the switch motor housing of the selector valve apart
the truck lost fuel pressure and died.

On another occasion
I've had a double failure, one of the O-rings on the pressure sidevalving failed and allowed some of the front tank fuel pressure to bleed into the inactive pressure line
from the rear tank fortunatly this didn't take much to fix I simply installed a factory inline check valve on the rear tank unit.

when the other O-ring failed in this valve the anti-reverse valve inside the pump proved itself to not be up to the task and I blew three gallons overboard (out the vent line and through the venting gas cap before the problem was discovered

you discover a problem like this and it's cold chils time...

I have not figuired out any "fail safe" way to control the return fuel to verify it is going to a tank that has room for it, the tank it came from, without using the factory selector valve. though my selector valve is now only controlling the flow path of the return fuel

the pressure side takes care of itself with inline check valves between the "T" and the Tanks.

AD

 

[adsm08]

wait what?
so a two way switch and.... whats the other piece?

If you have to ask that, you need to not attempt this kind of thing until you learn a LOT more about how vehicles work.

 

[this user name may change]

to asdm08

how do you teach any one given subject to a person without first giving the person an example?
you are the downfall of DIY'ers......(the utmost offence intended) how is one supposed to gain experience and knowledge without doing anything first?.,.... if your not part of the solution, your just in the way!.....(see i thought we were talking switches, but they were talking about relays...... see why i was allot confused?)

to AllanD

i owe many thanks to you and rangerSVT for all the help and heads up about what could happen if done wrong(the thought of burning to death is a lil creepy)
what would you use an electric selector valve or a manual selector valve?(like this one here)

 

[RangerSVT]

AD, I'm in aggreance with you that if it comes from one tank, the return needs to go back to the same tank it was fed from....What about using two solenoid valves, and having the return line just go to a T block, and between the T block and the tanks would be the solenoid valve, the tank that is supplying fuel would have the solenoid valve open for return, while the other tank's solenoid valve is blocked off, when the tank switch is positioned to the other tank, the power is also switched from one solenoid valve to the other, preventing fuel going to the other tank...
Here is one type of valve I am referring too...
http://www.grainger.com/Grainger/ASCO-Solenoid-Valve-4EKT9?Pid=search
SVT

 

[this user name may change]

ok if you were doing a completely custom wiring, could you hook up the electric valve up to the same relay as the fuel pumps or no?

Rangersvt
wouldn't you need a three way valve because the two way would just be an on/off =\= <= 2 way....(when valve is closed there wouldn't be another out)
...||
=\....= <=3 way kinda like these poor examples (third out allows for fuel to go to proper tank)

correct my if im wrong (just trying to make it as clear as possible)