Fuel tank selector switch...still won't work

[Diesel JD]

Well, I have a working brand new sender in the back tank, and teh front tank and gauges work fine, but I still cannot get the polarity in teh current to change. I know that I was advised a mechanical valve and gauges would be better, adn I agree, but I'd rather fix the electric system when teh problem is seemingly so minor...I was told all of teh functionality of switching the polarity is controlled in the switch, but I have replaced it with a new unit from Ford and still no dice. One more possibility, is there any way that the selector switch from Ford would not eb compatible with the Echelin universal valve from NAPA? The directions in the universal valve call for a 2 position always on switch, and there are 6 terminals on the Ford switch...but if I ask for a 2 position, both on switch at an auto parts house or hardware store people look at me like I have 3 heads...well, for those who have bypassed the factory switch, fixed a similar issue, gone mechanical, or have any helpful ideas or even wild guesses, I'm listening....,
Thanks,
J.D.

 

[argve]

jd

real quick here is how you swap polarity with a switch

 

[Diesel JD]

still confused.....anybody that can explain that diagram, I appreciate it a lot, thanks Travis, can this be done with any switch or one of those 6 terminal DPDT switches???

 

[argve]

I must appologize as I started that post when my sister called to let me know about my niece (she had an industrial accident at work tonight - hot scalding water over 1/3 of her body so the above message was very very short...) but I'm sure you can understand...

anyhoo... I'm at work now so I got's lots of time and paid time at that...

this is how you reverse the polarity with any DPDT switch (which I'm sure is what Ford was/is using) You should have on your universal tank selector switch 2 wires that control the action of the valve. When forward biased the tank will allow flow to and from the front tank and when reverse biased then the rear tank. Then you should have wires associated with the tank senders... Two wires go to the rear tank, 2 to the front tank and then lastly two to the gauge...

Is this the case... I'm a little foggy at this point on the diagram we talked about the other day... I just wish you were closer because I'm sure I could figure it out pretty easy if I was under the truck... so why don't ya just load up with homebrew and motor on up here and we'll make a weekend out of it... (long way to go but could be fun)...

 

[Diesel JD]

Thanks Travis, I hope your niece is OK, I hate burn injuries they are the most painful, so it is understood! Umm, the only thing that's confusing about the DPDT switch is that Ford has 4 red wires and 1 black and one brown/white going to the dash mounted switch....the only thing I can think of is could it be that the black wire is a ground, and it needs all 4 of those red wires to switch polarity as you showed me in the earlier daigram...and the brown white wire is the universal gauge wire?

 

[Agnem]

Travis, are you sure about that diagram? Usually a polarity reversing switch looks like an X between the outer poles, with the power fed to the middle two, and power taken off at one of the ends.

 

[argve]

yep - I'll stake my rep on it... It only looks different because I didn't draw it like an X but look at the current path... The tank switching valve is your load and the 12V is your source along with the ground symbol...