70 FJ40 Fuel gauge mis-reading

[JimmyMac]

I've waddled thru lots of these threads looking for a similiar problem to mine but haven't had much luck. My 1970 FJ40 gauge will only read ~1/2 tank when full and goes well below E when empty. When the ignition is first turned on the needle raises slowly to 1/4 then drops slowly to its level. My thoughts were that its either Sender, wiring/grd or a gauge issue. I jumpered a wire from the sender to a known grd, tank sender is new OEM from FJparts, which to me just leaves the gauge as suspect. Is there a way to verify its operation w/o removing the cluster? if not, then is it a matter of terminating it to grd and see how it reacts?

 

[Finally Mine]

Seek out bj40green, he has great write ups regarding the cluster panel and it's gauges.

 

[bj40green]

What is the part number from your new sender?
It should be 83320-35020. If it's 83320-60050 you have the wrong one.

There is no factory test for checking the gauge like there is for the '72 and later series.
You can check the gauge by grounding the sender wire while looking at your gauge. When the gauge reaches 3/4 to full remove the sender wire from ground to prevent that you burn up your gauge. This test (not the burning) will take 2 to 3 seconds. This will show that the gauge is OK.
If the gauge stops before it reaches the 3/4 - full mark remove wire immediately. It means that there is a problem with the gauge or the power to the gauge.

Hope that this gets you underway.

For more info on clusters, gauges and odo meters click here.

Rudi

 

[JimmyMac]

Rudi,

I grounded out the sender wire and was able to get the fuel gauge to continue to at least 3/4 ( I disconnected at that point). I also conformed with FJparts that the sender unit was the correct OEM#. So that leaves me thinking that maybe its an issue with the sender itself, could it be installed improperly? I believe there are 6 screws, so it can it can be positioned every 30 deg...I cant think why that would matter... or could it be that the float rod needs to be bent to correlate with the actual level in the tank? Kind of like calibrating it. I do know that this a different tank, Non-Calif emissions, and I dont recall if there was a differences in them other then the # of tubes to support the canister etc.

 

[bj40green]

Hola Jimmy,

Let's check the sender first. Please check the sender with an ohm meter.
The ohm reading should be smooth going up and down while moving the float.
The best way to do this test is with an analog (needle) meter. With a digital meter you'll see "rolling" numbers while you move the float so you have to stop, read, move a bit, stop, read and so on.
The readings should be:
Empty: 6.5 ohm
Half: 4 ohm
Full: 2.1 ohm

Let me know what you find.

Rudi

 

[sggoat]

So much for "new" technology digital meters. They are all junk, in my opinion. A good analog meter is a "perception" gauge---you can tell where it's going, and how fast in an instant. You do not need accuracy to the 14th digit.-useless
my .02

 

[JimmyMac]

Fuel gauge saga continues

Hey Rudi,

Still having issues, I unplugged and grounded out the fuel sender wire, dash fuel gauge continued towards 'Full', I unplugged it at ~3/4F to prevent burning of the coil. Assumed dash gauge is good.

Checked power and do have 12V, ground is good

Verified that the pn# of the sender is the correct one.

Removed the new sender from the tank and manually moved the float, could not get it to read on the dash gauge much over 1/2 maybe 5/8th at the most.

Tried getting an ohm reading, however I'll I have is a DMM I can not find anyone with an analog meter. Readings varied substansially. one item to note is I think your table for what I should be seeing is incorrect, 2.1, 4.5 and 6.5 looks like the tolerance and not the total resisitance of the sender . I found another document that I have attached showing the numbers....these are in the range that I see however they just keep bouncing around and I cant get a definite number.

Any thoughts? getting an accurate ohm reading is bugging me the most, could the wiper be that sensistive?

stumped...

 

[fzr400guy]

I'm experiencing a similar issue with the fuel gauge in my March 1971 FJ40. When full, the gauge will only go up to just under the 3/4 mark. It stays in that position till the fuel level coincides with it. Then it functions as it should.

 

[bj40green]

It seems that after almost 2 years you guys pointed me out an error that I made in my Cluster thread.
Here is where my data comes from (website from a Texas based parts supplier).

I always assumed that they put these numbers at the wrong (72 - 79) sender.
So that the early sender [STRIKE]83310-60011[/STRIKE] 83320-35020 was: 2.1 - 4.5 - 6.5 ohm
and the later sender 83320-60050 was: 17 - 45 - 120 ohm.
But as you guys pointed me out those numbers are from the tolerances in the '73 and later FSM.

So now I have to edit my other thread. Chips!

If that is the case (and I'm pretty sure about that) it would mean that your sender is in the same ohm range as the newer one. Namely; 17 - 120 ohm.
If that is correct than you can do the same test as per the manual with the 3W test light bulb.

Hmmmmm Time for a or to think this over.

I'll be back in an hour or so.

Rudi

 

[bj40green]

1 hour later

Okay, I'm back.

I'm going to start a new thread to ask who knows the ohm value of your sender.

In the meantime try to measure the ohm values of your sender as Mud member FJ718 did.






You should read a steady number with the sender on the table. If you have changing/rolling numbers the sender has a bad contact between the slider contact and the resistor.
I don't say that your ohm values should be the same because the values in the pics are from the newer sender ('72 and later). They can be different.

Rudi

Ps. I just posted the question here: -► https://forum.ih8mud.com/40-55-seri...lues-early-83310-60011-up-72-fuel-sender.html

 

[JimmyMac]

Fuel Sender

PN#83310-60011 I believe is superseded by PN#83320-35020, I just found the original box that my sender came in and that is the number on it. The 83310-60011 shows as unavailible at toyotapartszone.

Regardless, I still cant get a number that I believe. It will 'search' for a number from lo to hi or sometimes it will just sit at one number as in the picture where it stays ~19 throughout E to F.

The reason I bought the new one was that my old one did the same thing, constantly searching and not giving me reliable readings.

What is interesting is when it is hooked up in the tank it will read way below E and then go only as high as 1/2F, acting like the scale is shifted to the left.

Are these that fragile? would you suspect a bad sender? I will see about returning it...crossing my fingers

 

[bj40green]

Hmmmmm, I think you're mixing some up
PN#83310-60011 is the FUEL Gauge
PN#83320-35020 is the FUEL Sender

Mud member Downey responded that the values should read:
Empty: 110 ohm
Full: 3 ohm
So far it looks to me that you have a bad internal contact in that sender.
I assume that they are old as in "not recently manufactured" so maybe overtime corrosion had a chance.

Let's wait a bit for more input.

Rudi

 

[JimmyMac]

D'oh

sorry, I realize now that # is in your first post...maybe one to many

 

[bj40green]

Funny, I see your mistakes but not my own.
Nope, not one too many, my fault, I think I was almost asleep.
I've corrected the posting.

Rudi

 

[Cabane]

I have a 7/70 the Po replaced the sender and gauge with aftermarket. Said gauge was burned up Turns out a wire solder connection came off the gauge. Works fine after re-soldering. I want to use the factory gauge cause the wiring done for aftermarket was cobbled. And I want the factory gauge. The aftermarket sender is roughly 267 ohms to 35. Has anyone rescaled their sender with a parallel resistor? I think a 250 would get me functionally close. What do you think?

 

[Cabane]

Gauge wire

 

[Cabane]

Doh. Found thread spark_mark that answers my question... 2 470 ohms in parallel

 

[Solace in Solitude]

Hmmmmm, I think you're mixing some up
PN#83310-60011 is the FUEL Gauge
PN#83320-35020 is the FUEL Sender

Mud member Downey responded that the values should read:
Empty: 110 ohm
Full: 3 ohm
So far it looks to me that you have a bad internal contact in that sender.
I assume that they are old as in "not recently manufactured" so maybe overtime corrosion had a chance.

Let's wait a bit for more input.

Rudi

Looks like you've figured it out Rudi ( @bj40green ) - but, check Downey's post# 6 in THIS thread.

 

[Imurdaddy]

Rudi,

I grounded out the sender wire and was able to get the fuel gauge to continue to at least 3/4 ( I disconnected at that point). I also conformed with FJparts that the sender unit was the correct OEM#. So that leaves me thinking that maybe its an issue with the sender itself, could it be installed improperly? I believe there are 6 screws, so it can it can be positioned every 30 deg...I cant think why that would matter... or could it be that the float rod needs to be bent to correlate with the actual level in the tank? Kind of like calibrating it. I do know that this a different tank, Non-Calif emissions, and I dont recall if there was a differences in them other then the # of tubes to support the canister etc.

So did you ever get to the bottom of this issue?