fuel gauge problems 79 k10

[blackvnm]

79 k10 duel tank  person before me  cut the driver side tank hoses and hard wired past the selector on the passenger side but the gauge reads empty when turn the truck on  and sometimes when the truck is off the gauge will creep up to 1/4 just about  but takes a while does the selector in the dash mess with the gauge selection i have it on right side atm but if i put on left it still doesnt do anything  got both tanks out of truck atm and the gauge cluster out were to start lol

[Daniel Angel]

Hello,

I'm a newbie too, but I just finished installing a Dakota digital HDX system. In my dual tank k-20 and I can say it was one of the most challenging problems I ever did. Once I finished the install all the systems worked except the fuel gauges. This is what I learned from mine.
The sending unit on the right side or passenger side must be ground to the HDX system tied into the OEM sending wire on mine it's the pink single wire for the old system. So I ran a single 16 gauge wire directly from the sending unit. I used a circle connector and set it on the sending unit post then put the original sending unit back on top. It just clips back on. I checked a bunch of you tube vids and several suggested to cut an access door in the bed but there was a bunch of guys who really hated that set up because it meant cutting a huge hole in the bed. I don't think that's a bad solution if you just use your truck for hauling to the dump or bashing around but in my case it wouldn't have worked anyway because the sending unit sits between the cab and the bed so if I had cut a hole in the bed I still wouldn't have been able to reach anything. Since you went ahead and dropped the tank it doesn't matter. Again I can only talk about my system but the correct ohm readings for mine was 0-90 ohms and using the right side or driver side wouldn't give me a tank reading for the passenger side only the left or driver side. Once I set it up as described it now works perfectly. You said that the previous owner bypassed the old switch I can't say since it's not my truck but if it was me I'd try and re work it back to the OEM system and go from there. I'm just guessing but from what I can tell the tank switching system doesn't seem to be connected to the sending unit. I think it's an independent loop and the sending unit just uses the ohm resistance to measure and send a signal to the gauge and the switch just changes from left to right on a separate loop maybe one of the pros can give you better information but that's what I just got from mine.
Good Luck and I hope that helps you. I looked every where for this info and the Tech guy from Dakota Digital tried to help me but I don't think we were ever on the same page I think he understood the electrical system but not how my tanks were installed.

[blackvnm]

so far iv tryed alot of stuff  ohmed the tank sending unit said 62 little over half full  still cant get to read on gauge grounded the sending unit right to the battery and ran a ling from the unit to the gauge and plugged it into the sending unit prong on back of gauge still nothing wont move off E but when i shut the truck off still creeps up to 1/4 but as soon as turn the key back to E,  ive tryed grounding the prong on the gauge to the battery also and ts getting its 12v to it but just no sending unit reading

also would a 84 gauge cluster work only thing different is i have a manual oil pressure over the electric the 84 has but i can switch it out

[bd]

testing when apart makes job more difficult lol have you checked wire diagram in technical forum gauge needle creeping to 1/4 with truck off is common and insignificant dash fuel gauge has three connections 12 volt ignition ground and sender with everything hooked up ignition on will gauge needle point to empty if unplug sender wire if it does sender leg of circuit is constantly grounded  the factory selector switch in dash as originally built messes with gauge between tank sending units and energizes tank selector valve you may find a po bypassed switch so gauge is always connected empty tank how many wires go to selector valve   

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