Fit old style fuel sense float arm to new

[DSRTRDR]

let me see whether I can find a pic . . .

 

[DSRTRDR]

look at the pics starting here: the DSRTRDR is getting some TLC . . .

scroll down a bit to post 756, that has the tank info

 

[krudo]

You did that with a hand grinder?

 

[DSRTRDR]

"Tools R Us" here on MUD did - he posted the pics and description, too

 

[krudo]

"Tools R Us" here on MUD did - he posted the pics and description, too

Impressive! I'll give it a closer look when im on the pc. Looks promising

 

[bj40green]

Ask Rudi, I'm not sure if the 7 volt drop is built into the sender, the gauge, or the harness?????

The pre 9/72 cluster has a FUEL gauge and sender with a built in VR.
The 9/72 and later cluster has a FUEL gauge with a built in VR that provides the working voltage for the FUEL sender AND the TEMP sender.
Besides that.... the look of the gauge face plate is different.
I say it again; clusters and sender are set! You can't mix or change the FUEL and TEMP senders from one generation with an other generation.
The OIL circuit is a different story.

Rudi

 

[Downey]

^^^^Which is why we always found it easier to just run an aftermarket fuel gauge with a matching sender on the 8/72-older rigs.

 

[bj40man]

Hello,

I dont mean to hijack this thread but what Rudi said makes total sense with my reality. I have a 24v bj40 and I ended up swapping the fuel tank for a bj70 series one. The sender never worked ok. So one question, would it be because Im on 24v and the sender is for 12v that I get erratic readings? Could you chime in please?

My bj40 is 24v and its a 1975 model year
Thank you, and my appologies as well!

 

[bj40green]

Hello,

I dont mean to hijack this thread but what Rudi said makes total sense with my reality. I have a 24v bj40 and I ended up swapping the fuel tank for a bj70 series one. The sender never worked ok. So one question, would it be because Im on 24v and the sender is for 12v that I get erratic readings? Could you chime in please?

My bj40 is 24v and its a 1975 model year
Thank you, and my appologies as well!

Your sender is the same as for a 12V system. On the back of your cluster is a dropper resistor that drops the voltage from 24V to 12V both for the FUEL and the TEMP circuit. You can read all about it here: -► Clusters, Gauges, Speedo & Odo meters goto page 2 post #24 for explanation.

Please explain "erratic readings" to us.

Rudi

 

[bj40man]

Thank you Rudi for your clarification! It helps me so much.
So to clarify what I mean with erratic readings - It would work for a few minutes, then go to empty, then again working for a few minutes and then again to empty and so on. My situation is that I swapped in a BJ70 series fuel tank (bigger and deeper -21 gallons) and installed it behind the rear differential. I first tried connecting the 70 series sender but got no response, so then replaced it for an aftermarket one for a mini truck, then I just gave up.

From looking at another thread, you mentioned that the later *J40 series senders work just the same as the second generation ones, with the only difference being the longer arm, so maybe I should go ahead and try that first.

Once again, thank you very much for all your input!

 

[bj40green]

From looking at another thread, you mentioned that the later *J40 series senders work just the same as the second generation ones, with the only difference being the longer arm, so maybe I should go ahead and try that first.

The 3rd (in cab tank) and 4th (under cab tank) gen. senders are equal but..... the 4th gen. has a longer arm and a ground terminal. Electrically they are the same.
2nd gen. senders are different because they have a VR (Voltage Regulator) built in. It's a different circuit compared with the 3rd and 4th gen clusters.
Forget any other sender than OEM. They won't work.
I say again: cluster and senders are a set!

Rudi