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@$!#! $ fuel gauge part 2

TommyD11730

TommyD11730

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So I went ahead and put a new TBI baffled tank into my 84 K2500 (drivers side). Also put a new Spetra sender in as well. Before assembling the tank I plugged the sender into the trucks harness to confirm the fuel gauge would move as I moved the sender. It did.
Assemble everything and go get gas. You guessed it, gauge reads 1/4 tank when I know I just pumped 20 gallons into it!
Checked with my power pro to confirm sender is grounded (it is). Removed that funky (pictured) connector with a sordless terminal. Nada.

Sorry guys just venting as I can't see what went wrong unless the new float isn't floating.

Grrrrrrrr!

20181026_164039.jpg
 
I'm using spectra parts in my saddle tank I'll more than likely have fuel in it tomorrow. Hope my float floats
 
Maybe you have an 80 gallon tank. :haha:
I’d measure the resistance between the sending unit and ground. Should be either 0 or 90 ohms if the tank is full, forget which one it is. IIRC 90 ohms is empty and 0 ohms if full. Someone correct me if I’m wrong.
If you have an electric pump in the tank you can always empty the tank with the pump and watch the gauge to confirm you suspensions.
 
90 is full iirc. Been looking for aftermarket gauges and that's what keeps coming up in my search anyway.
 
First thing, did you smell gas strongly as you filled it? If so, go back and hook up the hose between the filler hole and the tank...........

Otherwise, unless you had a sudden failure of the sending resistor or gauge, the most likely answer is either a float that doesn't, not too likely, or the float is hitting a baffle or something else inside the tank.

Good news, is that you can probably fix it by taking the screws out and rotating the sending unit so it clears. Bad news, you have to drop a full tank to do it.....
 
Got a roaring north easter at the moment, ain't working on it today. Did notice when I drove it and parked it, came out after 30 minutes and restarted it. Needle started sweeping to full , but fell back to quater.

Grrrr
 
Might be the gauge itself too...

The sending unit in my '82 GMC K2500 diesel just makes the gauge go way past full all the time with the key on..
I was pissed after I got the tank in (swapped a good used one in place of a leaker),and then discovered the sending unit I took off the old tank was NFG--truck used to have dual tanks and I had run it off only the right side tank until that one leaked,then I got a good used tank and put it on the drivers side,assuming that sending unit was OK..

I have just written the mileage down on the windshield with a magic marker when I fill up,and try to take note how long I've had it idling ,so I wont run it out of fuel--I can go about 300 miles on a full 20 gallon tank..

I have several "good used" and one brand new sending unit ,but they are for gas powered trucks--the diesels have a water sensor built into the sender to activate the "water in fuel" light,and also has an extra nipple and tube that goes to the bottom of the tank,that siphons out any water,it hooks to a manual drain valve near the rear wheels..

I could probably just transfer only the sending unit rheostat off one of the gasoline sending units to the original assembly,but I'm balking at dropping that tank again..I don't drive far ,so I've just used the magic marker as my "gas gauge" so far..
 
Any links to a wiring diagram for a 84 model that had dual tanks? Just want to be prepared in the event the sender ohms out good.

I'm beginning to think I'm nuts. I know I saw that ! $÷=_$@ gauge move when I plugged the new sender in.

Back years ago when I bought the truck it had no turn signals indicators or high beam indicator. The plastic "harness" on the cluster had some opens so I just jumped them out. They still work fine after the repair but maybe the circuit for the gauge failed.
 
The only wiring diagram I have for dual tanks is in a Haynes manual,and its so tiny you need a magnifying glass to see it..

I'd post it up here--but I found out my old HP scanner is not compatible with the newer Windows 8.1 computer ,(old XP one was 32 bit,this one is 64,and according to the list HP has listed,I cant get it to work with this computer..:( )...so I'm boned until I can afford to upgrade..

I have tried taking a picture of the diagram with my camera,but I cant hold it still enough to come out focused...maybe you can find a diagram on Google ?..

I ended up extending the wires from the passenger side tank to use on the drivers side--some hack chopped out all the valve wiring and the valve to switch tanks,and the dash switch before I bought the truck..
I knew that side worked,so I just cut and spliced them to reach the drivers side..
 
Did just have a thought. After testing the sender on the trucks harness I installed it in the new tank.

The tank took some additional pounding with a dead blow to get the mounts and straps on.

Maybe that pounding wasted the new sender. If so.

I'm a dope. :)
 
Highly doubt it’s wasted. It’s not like it’s an electronic device, it’s more mechanical. The sender is actually a rheostat, a variable resistor, that has a wiper arm that rubs against a contact. You may have bent the wiper a little but you can easily bend it back. I did that on my original sender when I replaced the fuel pump and then I tested the movement out with my ohm meter. I also cleaned the contacts off, forget what I used though since it’s been ages since I did that.
 
A little off subject, don't the salvage yards put holes in gas tanks? Can't get a good tbi tank there?
 
Looking for diagram for 84 gmc cluster harness connector ... anyone???
 
I put two new Spectra TBI saddle tanks and senders into my truck. The senders read OK at more than a half tank, but they start to read about 1/8 of a tank low when under a half tank. Those Spectra fuel tanks senders are not the highest quality senders. The problem is that they are the only ones out there for the square body Chevy truck. I think I remember that those Spectra fuel tank senders come with a terminal-end/pigtail in them for the updated power wire terminal, but I did not need it because my truck came factory with a newer version of the power wire connector.
 
Most salvage yards here,if not all nowadays, poke a hole in every vehicle's gas tank and drains them into a big barrel or tank ..
EPA came down on many yards here for not being too careful about fluid spillage..

The holes I've seen them make are done with a air chisel with a bullet tip,that could probably be plugged easily or patched with a welded plate,if your brave enough to try welding ,if you fill the tank with water and dump it out several times,then fill it almost full you can weld a patch on --seen a few guys use one of those poke in rubber oil pan drain plugs to seal up the hole in a salvage yard gas tank before..maybe you could even put a drain plug in the hole by welding a nut or pipe coupling to the tank where the hole was..
 
84 ohms at harness to printed circuit.

Anyone have any luck with the repop printed circut? Same for the fuel gauges?

Unexplored territory here.
 
So sender sees almost a full tank.
Let’s back up for a moment, why’d you replace the sender?
 
Full field test at sender wire. Passed the F to E test. I'm guessing I was just unlucky enough to test the system when it was working.

The printed circuit has already been repaired once by me. To me it's only a matter of time before more circus fail.

While I had the cluster out I cleaned the contacts for the harness.

Fuel gauge worked for about 5 minutes. So, I'm at the point I pull the cluster and replace the printed circuit and gauge.

Just wondering if the aftermarket is better then buying someone else's "junk" off ebay.

rampage said:
So sender sees almost a full tank.
Let’s back up for a moment, why’d you replace the sender?
Click to expand...
 
What’s the reading of the gauge when the sending wire isn’t plugged in and when it’s shorted to ground? Gauge should read full and empty respectively.
 
Not sure, did no do full field test today.

Tapping on back of cluster makes the gauge rise from 1/4 to the correct reading of F. Plug from sender shows 84 ohms.
So as I have already fixed the printed circuit once I'm guessing bad circuit and or gauge.

rampage said:
What’s the reading of the gauge when the sending wire isn’t plugged in and when it’s shorted to ground? Gauge should read full and empty respectively.
Click to expand...
 
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