Dakota digital users, fuel gauge

[Subourbon]

hey guys,

I got dakota digitals vhx in. They look wicked, big fan!

But, my fuel has never ever worked since I got the truck. I was past full, on oem gauges, Then one day it was half. I dunno, then I got a new printed circuit, tried that. It was at a 1/4 then went past full again.
So that suggests the gauge worked? Just bad signal?

Upon doing setup with DD vhx gauges, I got error message EEE which is open circuit or bad sender or bad signal wire.

It's a suburban so I've got that tank thats really tucked away up there close to the body, not a side tank like pick ups have. And I can see the square root of jack sh!t.

Really annoying, anyways I assume it was a ground issue, Im In canada, so lots of rust. I found a black wire bolted to frame, couldn't see it, all by feel, anyways the bolt felt rusty as F.

Cut that wire off and spliced in a new length and ran it to behind my license plate, where I drilled a hole and bolted a ground in.
Because, my license plate light didn't work, and I got new one and grounded it there. And they work. So, I figured, what good for the goose is good for the gander.

Or am i stupid and should I ground it to frame?!?!?!

No joy. Still got the same EEE code.


So thats where im at, maybe the ground isn't connected on sender side, I pulled ever so slightly to see if it was connected. It was.

Bad sender? Like I said, salt in roads here and I have hard fuel lines. Replacing sender will definitely involve replumbing all of thr system. Which.... I ld rather not do, the lines look angry..


Bad signal (pink wire), I would've liked to do a continuity test, but I cannot for the life see anything, but earlier i said my gauge moved, so... that means it was getting a signal?! I dunno anymore. I lived with fuel gauge not working for years, but dakota digital aren't cheap, and I'd really like for them to work!

I thought maybe just loosening the straps on the tank and taking a peak but, they're rusty too.
I'm venting and wondering what my next move should be.

I might cut pink wire where I can see it and run a new lentght of wire up to the DD control box, that way I know the wire as an issue is eliminated. If that doesn't work then it'll be a sender job I guess.

This is semi a cry help and a bitching session.

Thanks for any advice

 

[gmbellew]

i think the sender grounds back by the tank? might check there as a starting point.

 

[Subourbon]

Yeah the ground i found was up on the frame rail near the driver side shock upper mount. I couldnt see anything else in that area that looked... ground-y

 

[Bextreme04]

Yeah the ground i found was up on the frame rail near the driver side shock upper mount. I couldnt see anything else in that area that looked... ground-y

The wire is a simple circuit through a variable resistor on the fuel level float to ground. There are multiple pins on the original cluster connector that could go to the fuel sender. You should use a multimeter to check resistance between each pink or tan wire on the original connector to ground. When you find one that has between 0-90ohms... you have found your fuel sender wire. You can verify by checking it while ~1/2 full(should be around 45ohms) then go put 5 gallons or so in it and make sure that signal has gone up. 0 ohms is empty and 90 ohms is full.

 

[Subourbon]

I dont know ifnill be above to through the original connector (18pin connector) I've already cut most of the wires to connect to the DD control box.
And at the tank in can't see what im doing. I can barely reach the sender.

 

[Bextreme04]

I dont know ifnill be above to through the original connector (18pin connector) I've already cut most of the wires to connect to the DD control box.
And at the tank in can't see what im doing. I can barely reach the sender.

I would check all the pink or tan wires at the connector. I would not mess with the tank unless I could not find the functional wire

 

[Subourbon]

Ill try again in the morning.
There was a pink and tan wire stuck together coming down from the tank and running along the frame rail towards the front of the truck. But im confused as to what the tan wire does.
Ill check it out when its light out in the morning... find out where the tan wire goes

 

[Subourbon]

I've got 1 tan wire on my 18 pin plug. Number 5, which is for oil pressure, which is not longer used.
And 2 tan with white tracer, number 17 I believe, but thats brake warning indicator light from proportioning valve & parking brake.


So I'll need to find out where thst tan wire goes

 

[Subourbon]

Ah... the tank wire must go to the water i fuel lamp (WIF) I have a diesel.
Senders with 3 wires are just that,
Ground
Signal for gauge
And WIF.

WIF never came on, typically they should come on, like the low coolant lamp as a systems check when turning the key on. But mine ever has. So either coz the ground was bad. (But I've fixed the ground.

Or bad connection, or bad wire....

 

[Turbo4whl]

The GM fuel gauge does not use a voltage regulator like many other brands back then. To keep the gauge from bouncing and work with varying voltage, the gauge has 2 small electric magnets. One pulls towards full, the other to empty. The resistor mounted on the back of the factory gauge needs to be the correct match for the tank sensor, also a resistor (variable).

Good chance the tank sensor is bad. Hack trick, cut a hole in the rear floor to swap out the tank unit. Floor metal plate to cover the hole located with a few short, sheet metal screws. Carpet or mat hides the hack.

 

[Subourbon]

That's an option. Id really rather not cut a hole in the floor.
I've got so much stuff in the back lol.

But, the water in fuel light, which in theory, when you flip key on, momentarily brake light comes on fasten seatbelt, low coolant, WIF etc etc, they all come on except the WIF light.

I'm looking for wiring diagram to see how and where WIF is grounded.

Basically, my hope is that the wires (pink n tan) just aren't plugged into the sender and my solution is just that.

If thats not it then I'll wait till spring and get the lines I need to inevitably replace, and drop the tank I suppose.

 

[Bextreme04]

That's an option. Id really rather not cut a hole in the floor.
I've got so much stuff in the back lol.

But, the water in fuel light, which in theory, when you flip key on, momentarily brake light comes on fasten seatbelt, low coolant, WIF etc etc, they all come on except the WIF light.

I'm looking for wiring diagram to see how and where WIF is grounded.

Basically, my hope is that the wires (pink n tan) just aren't plugged into the sender and my solution is just that.

If thats not it then I'll wait till spring and get the lines I need to inevitably replace, and drop the tank I suppose.

On an 82, they should be metal lines only to just off the frame rail. Then you should have rubber from the frame rail to the sending unit. There is a metal post on top of the sending unit that the fuel level sensor clips onto. There is another metal post on the side of the sending unit that has the ground wire connected to it.

82 was an in-between year and also the first year for the 6.2 diesel. I think you only have the 3-port sending unit for diesels... but I'm not sure. I also thought that the Water in fuel sensor was on the fuel/water separator mounted on the firewall... was that only for CUCV's? You could also have a 25, 31, or 40 gallon tank. Based on your comments, it sounds like your best bet might be to replace the sending unit and tank strap kit.

I have a 31 gallon EFI blazer tank in my pickup. I've had it down several times to mess with the sending unit and wiring and it isn't too bad when the parts aren't all rusted out. I would be very tempted to just order all new strap kit and sender and then cut off the old straps and drop the tank. LMC has both the sending unit and strap set for all size tanks and you could have both plus shipping for around $100-200 USD. I will say that whatever cheap senders LMC uses are marginal quality. The only one I have ever ordered from them was bad right out of the box and would not read a consistent level. It would go from full all the way down to 1/4 tank, then go back up to right above half tank, then drop down to 1/4 tank again when the tank was actually empty. I replaced it with a Dorman unit and it has been working perfectly ever since.

https://www.lmctruck.com/fuel-system/gas-tanks-parts/csb-1973-91-gas-tank-and-components


It is interesting that they only list diesel stuff from 84-up... I wonder if that is a typo and it actually applies to 82-up.

 

[Subourbon]

@Bextreme04

Yep, metal lines all the way up to the tank, coz I just redid the brake line that runs up there to the rear wheels. .
And it is 3 outlets. Supply to pump, return line and the 3rd is a lil drain valve that I saw and was wondering wtf it was!

I saw where the ground goes based on pictures I've looked at of senders. Looks kinda fragile!

As for the other connectors, all I saw on the pics of senders are lil threaded studs or pins with nuts that look like a crimped ring terminal would go over it. I thought it'd be a connector with a tab that clips on or whatever,.

I believe its the 25 gallons tank, maayyybe 30 but def not 40. I dunno coz I never ran it dry lol, she's kept full almost all the time.

Firewall fuel filter: i thought the same as you and I jist went out there to verify, ive got spin on filter, not the rectangular filter. And theres no wires nothing that looks like a sensor goes in there. I believe the WIF se sor on filter was the later 88 to 91 6.2s, and then later on the 6.5s. I think i was reading a post about this thing in steel soldiers where so e mentioned the wIF being back there.

Definitely jealous of pick up drivers and their fuel tank placement right now.

I think you're right, as far as replacing everything.
I really just need the sender, but, I've learned to prepare for worse. Straps, rubber hoses etc..

I jist wonder if I can drain the tank in that lil drain valve that would be wicked lol.

Thanks for the detailed answer definitely very helpful as far as the part research. Ill see about finding a good quality Dorman round here. Really wanna avoid shipping from the states if I can!

 

[Bextreme04]

@Bextreme04

Yep, metal lines all the way up to the tank, coz I just redid the brake line that runs up there to the rear wheels. .
And it is 3 outlets. Supply to pump, return line and the 3rd is a lil drain valve that I saw and was wondering wtf it was!

I saw where the ground goes based on pictures I've looked at of senders. Looks kinda fragile!

As for the other connectors, all I saw on the pics of senders are lil threaded studs or pins with nuts that look like a crimped ring terminal would go over it. I thought it'd be a connector with a tab that clips on or whatever,.

I believe its the 25 gallons tank, maayyybe 30 but def not 40. I dunno coz I never ran it dry lol, she's kept full almost all the time.

Firewall fuel filter: i thought the same as you and I jist went out there to verify, ive got spin on filter, not the rectangular filter. And theres no wires nothing that looks like a sensor goes in there. I believe the WIF se sor on filter was the later 88 to 91 6.2s, and then later on the 6.5s. I think i was reading a post about this thing in steel soldiers where so e mentioned the wIF being back there.

Definitely jealous of pick up drivers and their fuel tank placement right now.

I think you're right, as far as replacing everything.
I really just need the sender, but, I've learned to prepare for worse. Straps, rubber hoses etc..

I jist wonder if I can drain the tank in that lil drain valve that would be wicked lol.

Thanks for the detailed answer definitely very helpful as far as the part research. Ill see about finding a good quality Dorman round here. Really wanna avoid shipping from the states if I can!

You'll need to know what size tank in order to get the right sending unit, as they are different depth tanks. You can measure the tank to know what size it is. They are visually pretty different as well. 25 and 31 gallon are square looking and only differ in depth of the tank(which is why the size matters for the sender). If you order a 25 gallon sender, but have a 31 gallon tank you will run out of gas with 6 gallons of usable fuel left.

25 Gallon: 28"x28"x10"
31 Gallon: 28"x28"x13"
40 Gallon: 35"x28"x13"

I can't seem to find a diesel sending unit at all for 82-84. I bet they had the WIF sensor in them, and they were probably an issue, so they got swapped to the firewall filter in 84. No one seems to reproduce the one with the WIF sensor anymore. I wonder if a previous owner swapped the sender to a non-WIF sender at some point in its life and connected the wrong wire to the sender. I'm not sure what the stock sender wire would have looked like when it was supposed to have two wires on it, but the early sender wire connections with just the threaded post on them would have had a single covered connector that just pushed onto it. You could also have a nut holding it on, but the stock ones just had a round split push spring type deal on them. Heres a pic of a connector where you can see the end well:

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and the link to an ebay listing for the replacement wire pigtail. https://www.ebay.com/itm/2762870573...Kkjqz72EpNn_dAzVlHygi-DFR3tQJMBcaAhZeEALw_wcB

You used to be able to buy these pigtails at your local autoparts store... not sure if that is still a thing. These connectors are often not pushed all the way on, or the rubber cracks, or whatever, and then water gets in and corrodes the connector. I usually fill the connector with dielectric grease like Dow Corning DC4 to prevent this.


Also, you will have metal lines up to the tank, but then a piece of rubber connecting them to the sender. There should not be metal line connected straight to metal outlets on the sending unit. You will have a three connections, one is the vent for the tank when filling(5/8" large hose that runs next to fill tube), one is the feed line to the engine(3/8" line), and the last is the return fuel line from the engine(1/4"). The tank pressure is vented through the fuel cap because its a diesel.

 

[Bextreme04]

I jist wonder if I can drain the tank in that lil drain valve that would be wicked lol.

I would disconnect the feed line from somewhere and pump straight out of there. Alternatively, you can drop a hose down the fill tube and just siphon or pump it out. Harbor freight has some cheap options(not sure if you have harbor freight in Canada), or even Vevor.

https://www.harborfreight.com/750-gph-drill-pump-56847.html

The drill pumps use a standard garden hose connection and you can get a garden hose to 3/8" barb brass adapter at most home and garden stores.

https://www.homedepot.com/pep/Everb...oYsaliPjfxfFTe1MlskIyjxIZnM5EA0caAu8KEALw_wcB
Then a simple 3/8" fuel line will connect the drill pump straight to the vehicle fuel feed and you can pump it all the way down to empty.