Dual tank fuel guage question...

[77f2504by4]

So i have a new to me 97 f250 HD. it has dual tanks, i have never owned a truck with dual tanks before so forgive me if this is a stupid question. the fuel guage doesnt seem to change when i am running on the less full rear tank. so its almost like the guage only shows the front tanks level. i dont think thats normal, but what would cause it? when i flip the switch i can hear the pumps changing, and it runs fine in either position, but it just seems like the guage isnt accurate when i am running the rear tank. maybee i am just paranoid. is there any way i can check this out?

Thanks Bob

 

[blacksnapon]

So i have a new to me 97 f250 HD. it has dual tanks, i have never owned a truck with dual tanks before so forgive me if this is a stupid question. the fuel guage doesnt seem to change when i am running on the less full rear tank. so its almost like the guage only shows the front tanks level. i dont think thats normal, but what would cause it? when i flip the switch i can hear the pumps changing, and it runs fine in either position, but it just seems like the guage isnt accurate when i am running the rear tank. maybee i am just paranoid. is there any way i can check this out?

Thanks Bob

We use signal generators that hook up at the sending unit connector to simulate the signals from the tank unit. You might unplug the sender and watch what the gauge does just to verify the wires integrity.

 

[Truckin4life]

Or.

make sure you have the front tank full....

Run the rear tank empty.

See how well the gauge works...

JJuust make sure the front tank is actually full, dont rely on a possibly bad gauge. haha

 

[77f2504by4]

well the other day when i put gas in it, i put 60 bucks in. i put 40 in the front tank wich was a little less than a 1/4 full and i put 20 in the rear tank that i was running on, it was reading just over 1/4 full. when i turned the truck on the guage had gone up past 3/4 full. which i didnt think was right, but maybe i am just paranoid. i plan on running the rear tank till empty and switching to the front (hopefully still full) tank.

 

[Alvin in AZ]

Figure this won't help you, but here it is anyway...

A week ago took a few Gen-8 sending units apart and found out the sliding
ground contact in them simply uses the stainless steel frame! :/ Cleaned 'em
up using a deburring wheel, removing the grooves best I could, made 'em read
20 to ~150 ohms slick and smooth and steady as anything. Before the cleaning
they were reading so crazy/jumpy I couldn't get the same resistance reading
twice.

Tinkering fool in AZ

 

[Truckin4life]

The rear tank is the smaller of the two...
I dont know the exact gallons off hand though.. But your gauge could be close... ish?
haha i really dont know, its been so long since ive been in my gen 9

 

[77f2504by4]

well so far i havent switched to the front tank yet and the guage is now getting to the 1/4 mark. i am going to run this tank till it gets below the E mark. this is a two fold experiment, i want to see if the guage is working, and how far i can push it without sputtering out. at the rate i use gas, it might be a few more days.

 

[77f2504by4]

so i believe that i was just paranoid. when my tank got down to the E on the guage i flipped the switch and the guage went up past the full mark. it has steadily been going down too so i know that the guage is working.

 

[Alvin in AZ]

Bob, if you're happy I'm happy, but if you want to test the gauges like you
mean business here's how to do it...

----------------------

To test the -temperature- gauge I bought 3 resistors from RadioShack and
hooked them up in series...

10 ohms + 22 ohms + 47 ohms = ~79 ohms
(10+ 33+ 33= 76 would work too, and for cheaper

Pull the wire from the sending unit and ground it through the resistors (or
resistor) with the key on.

With 10 ohms by itself is "hot".

With 79 ohms it reads "cold".

Putting 22 or 32 or 47 or 69 ohms, it reads "in between".

----------------------

Ok, Ford sez the -fuel- sending unit's resistance is supposed to be 15 ohms
to 160 ohms (unless it's the Bi-Metallic type then it's 10 ohms to 70 ohms).

I went to check the fuel-level-reading on my newly-re-installed bone-dry
32.0 ("33") gallon tank and had forgot to hook up the wires. LOL

It read fuller-than-full! LOL

So now it's easy for me to remember which way the gauge goes with what
resistance.

I looked it over good where the needle sat while the tank was bone-dry.
Put 3+1/2 gallons of gas in it and checked it out real close again, I'm
planning on remembering those spots.

I'm prob'ly not going to buy resistors to test the fuel gauges anytime soon.

--------------------

Anyway, if you want to test your fuel gauge and sending units there's all
the information and numbers you'll need.

Alvin in AZ
ps- I'm thinking about soldering a "ribbon" to my sending units I take apart
in the future, to bypass the two "grounding contacts".