toyospearo

This thread pertains to my 1982 22R SR5 shortbed pickup.
I recently swapped a 16 gallon longbed fuel tank into a short bed that had a 13 gallon tank. I swapped the 16 gallon tank with the sender. I did not swap a fuel gauge into the cluster from a longbed. I didn't have one.
Everything went pretty smooth. However, I noticed my fuel gauge reads as if the tank was 13 gallons. I drove the rig until the needle hit E and then I drained the remaining gas from the tank. There was at least 5 gallons still in the thank! In addition to that the OD read 170 miles! That is synonymous with the previous 13 gallon tank.
I had everything tested electrically on the sender, gauge, and volts to the gauge. Everything is within spec.
SO my question is: Is the shortbed (13 gallon tank) gauge in the cluster designed to only read just that, 13 gallons?
This is a very strange scenario. If I had available to me a long bed cluster I would test it out. BUT, those are VERY hard to come by. Especially mine. My cluster is the SR5 and has the tac in it. I did call the dealer about part numbers for the gauge of my year longbed and shortbed. The dealer comes up with 3 different numbers but does not specify which does what or what goes to where

toyospearo

bump. Any help on this would be GREATLY appreciated!

4Crawler

iTrader: (3)

Was the new tank longer or taller/deeper than the old one? If taller, then likely the sender, or at least the float arm, is different with the two tanks. Why? Taller/deeper tank needs to have a float arm that swings farther down to read empty.

toyospearo

I swapped the sender out. I installed the new 16 gallon tank with the sender that was in it.
It's the correct sender for a 16 gallon tank.

4Crawler

iTrader: (3)

OK, wasn't clear on what all was swapped.

I don't think there are different gauges, at least in the '84 and later trucks. According to the FSM, the sender should read 110 ohms empty and 3 ohms full:
- http://www.4crawler.com/4x4/4R_TechI...tml#Electrical

Makes no difference what size tank it is, but the sender should match the tank.

WHAHAHAJR

Don't know for this particular application but just thought I would ask was there any possible way the rod got bent. And does it only install in one way.

toyospearo

Good questions.
I made sure the rod was not bent or damaged in any way. It will install a number of different ways. I made sure it was in the way it came from the factory.

toyospearo

I have no idea what is going on. All the specs check out. My only conclusion is there is something in the gauge that reads differently per tank. I just wish I was SURE that's what it is.

toyospearo

In my 82 there is a distinction between "30 series" and "40 series."
What is a "30 series" opposed to a "40 series?" My FSM doesn't give me any info on "series." What do the number signify under the series column?
Here is a pic

vital22re

iTrader: (2)

that may be what the reading should be for that position on a different set of terminals... so it would tell you if you are at the halfway point.

toyospearo

wed morning bump

Leviticus6432

Well, i've looked into this a little bit previously, as I am trying to make a custom inst cluster. Looking at the back of my (non sr5) cluster, I see that there are 8 spots in the circuit for either a resistor or capacitor. Only 3 are currently used. I'm guessing they added components as needed. There is a capacitor connected between one four terminals and the one marked ignition. Perhaps changing the capacitor or adding a resistor somewhere in the circuit is what you need. Try to find a cluster on ebay and getting the seller to take a good pic of the back. Then you could prob just see what you were lacking.

moroza

Well, judging by photos, the 13gal and 16gal tanks are the same width and height, only the length varies. So the position of the float inside the tank should be the same for the same proportion of fuel remaining.

There're a couple of longbeds in the junkyard near me. Want me to pull you a fuel gauge?

mbk

I don't know if this helps but I have an 88 4x4 and the sender I'm the tank went out I put one from a 13 gallon tank in my 16 gallon tank and when I fill it all the way full of gas it reads a hair over half of tank on gauge in dash and when the gauge says 1/4 tank it's really got half tank and when it's on empty there's like 1 1/2 gallons left this prolly doesn't help you any though because I put the 13 sender in my 16 tank

toyospearo

That's to be expected I would think. However, the workings of these fuel reading/sensing units is still a little bit of a mystery to me. When I have the energy I am going to yank out the 16 gallon sender, take the arm off of it, put the arm on the 13 gallon original sender and see what happens. If that doesn't fix things I am going to give up on it and just deal with the irregular readings. I'm pretty much over it at this point.

clark-camp

I have a longbed with the 16 gallon tank. When my fuel gauge reads empty, I know from experience that I still have approximately three gallons left. I always assumed that this was some quirk that the 32 year old truck had. After reading this thread, I am getting a different idea about it though. If any other longbed owners want to chime in, we may get this cleared up without toyospearo having to disassemble his tank again.

RMA

man i really doubt the cluster is made to read 13 gallons .. the float arm has to be bent .. maybe not by you but maybe the previous owner of the tank and sender.

jgilk1

its actually more likely that your receiving unit in your cluster is bad if your float reads correctly on an ohm meter... the reading between a 13 gallon float and a 16 gallon float is null if both sending units ohm out the same... 110 ohms empty and 3 ohms full the sending unit....

what i would do is apply a 12v load through a 3-ohm resister in to your fuel gauge and see if it reads full then a more basic test run a 110 ohm load and see if it reads empty.... (full tank = 1/4 guage sweep, 1/2 tank = 3/4 sweep, empty= 1/8th tank)


i have owned 2 chevy cavaliers, my brother and his gf a celeberity and my uncle 2 99 chevy 1500 (one was his and the other was a dedicated work truck) all 5 experienced a malfunction of the gas gauge in under 40k miles when tested by chevy dealership they were with in stock spec as well but that doesn't mean they worked properly

so if your sending unit is good test your receiving unit (yes i read your original post) you stated that you have electronically had them tested to be with in oem spec... this only means that when the gauge has a test load that it works or functions but there is a big difference between a test bench test and actually functioning