Aftermarket fuel gauge suggestion

[dtrojcak]

Using information from this site, I have determined that my fuel gauge and my fuel sending unit are both defective.
I haven't checked the temp sensor or gauge yet, but from what I've read, they're probably toast also.

It seems that these Jeep's have a faulty design with the regulated 5volts that the fuel gauge creates. If you loose your ground, you fry your gauges and probably the sending units. This looks like what happened before I bought the Jeep.

This leads me to a couple of questions.
Is there a better, more reliable way to create the 5volts that the gauges need to operate rather than relying on the fragile ground in the speedo cluster?

What are the best, most reliable aftermarket gauges and sending units that will fit in the OEM speedo cluster?

I've read countless threads where people have been forced to drop their tanks within a few months of installing a new sending unit.
I would very much like to avoid dropping the fuel tank more than once.

 

[Torxhead]

My $.02 is the my replacement gauges and fuel level send unit made by crown, I think anyway, have worked for many years now. This way I am able to use the existing gauge locations. To eliminate any issues with getting at the send unit in the tank, some guys just cut a hole and make a small door in the bed of the CJ over that unit to get at it. I hear Autometer can help you with some gauges also.

 

[Old Dog]

I've read countless threads where people have been forced to drop their tanks within a few months of installing a new sending unit.
I would very much like to avoid dropping the fuel tank more than once.

That's what has happened to me on a couple occasions, I finally went to an Auto Meter gauge but now the Crown or Omix (can't remember what it is) sending unit has gone out again.

 

[dtrojcak]

Whenever I do drop the tank, I'm definitely going to cut an access panel in the bed so I never have to drop it again to replace the sending unit.

Are the new gauges that fit into the original speedo still "finicky" with their grounds? Meaning, do they burn up if they loose ground like the OEM gauges? Or do they have better 5volt regulators?
Better yet, is there a gauge and sending unit kit that can simply use 12 volts to eliminate the possibility of the 5volt regulator failure?

 

[IOPort51]

where is this regulator of which you speak?? I did not know that the gauge used anything but 12V.

The problem with aftermarket fuel gauges/sending units is getting the resistance to match. It is amazing how many different resistance there are and how few will work with the CJ sending unit. I think I found one at auto meter that will work and it was not in the style gauge I wanted to use. are you sure the gauge is shot?? the sending units fail pretty regular but the in cluster gauge is pretty tough. I touch 12V to the sender terminal on the gauge and it should peg.

I put a access panel in the back of My CJ5 . was not real hard and there is a flat place in just about the right place.


http://www.jeep-cj.com/forums/f7/fuel-gauge-sending-unit-access-panel-13584/

please elaborate on the 5V thing.

 

[dtrojcak]

From what I have read, the fuel gauge is hooked to 12volts.
It internally regulates that down to 5volts and passes it on to the temp gauge. That is why they are jumper ex together.
If the fuel gauge loses ground, the full 12 volts is delivered to the fuel gauge, the temp gauge, and both sending units. This usually fries them.

Yes I'm sure the gauge is faulty.
When I touch the sender terminal with 12volts, it does peg. However, the ignition terminal is a direct short to ground which pops the cluster fuse.
Upon opening the gauge, I found the first resistor winding melted to the arm it is supposed to move.
The sending unit is also faulty.
I should have somewhere between 10 and 70 ohms on the sending wire depending on how much fuel in the tank. I read 20-30 Mohms.

Or do the new gauges simply use the full 12 volts?

 

[IOPort51]

thanks for the input, I have never dismantled any gauge, guess I should some time. what you say makes sense.

 

[dtrojcak]

Every gauge problem thread I read made a reference to this one guy's troubleshooting guide.
He goes into great detail of how and why the gauges work like they do.

 

[DHugg]

From what I have read, the fuel gauge is hooked to 12volts.
It internally regulates that down to 5volts and passes it on to the temp gauge. That is why they are jumper ex together.
If the fuel gauge loses ground, the full 12 volts is delivered to the fuel gauge, the temp gauge, and both sending units. This usually fries them.

Yes I'm sure the gauge is faulty.
When I touch the sender terminal with 12volts, it does peg. However, the ignition terminal is a direct short to ground which pops the cluster fuse.
Upon opening the gauge, I found the first resistor winding melted to the arm it is supposed to move.
The sending unit is also faulty.
I should have somewhere between 10 and 70 ohms on the sending wire depending on how much fuel in the tank. I read 20-30 Mohms.

Or do the new gauges simply use the full 12 volts?

Five years of living without fuel or temp gauges... unreal!

The 12V input to a 5V system; touch GND anywhere and your gauges are dead.

There are solid-state voltage reduction devices, 7805 or LM340-5, others, that reduce an input like 12V to a constant 5V. Total cost if you did it yourself probably $3. I just made a pair Monday and Tuesday, and will try them out tomorrow, Thursday.

I have both fuel gauge and temp gauge wired up to use 5V.... I will know soon.

I'll post 5V regulated power supply to this on-going build:
http://www.jeep-cj.com/forums/f98/build-new-set-gauges-scratch-22266/

 

[IOPort51]

I had wondered when one of us would discover a use for one of these programmable micro processors. I keep thinking fuel injection/ignition control. well done on your project.

Five years of living without fuel or temp gauges... unreal!

The 12V input to a 5V system; touch GND anywhere and your gauges are dead.

There are solid-state voltage reduction devices, 7805 or LM340-5, others, that reduce an input like 12V to a constant 5V. Total cost if you did it yourself probably $3. I just made a pair Monday and Tuesday, and will try them out tomorrow, Thursday.

I have both fuel gauge and temp gauge wired up to use 5V.... I will know soon.

I'll post 5V regulated power supply to this on-going build:
http://www.jeep-cj.com/forums/f98/build-new-set-gauges-scratch-22266/

 

[dtrojcak]

Five years of living without fuel or temp gauges... unreal!

The 12V input to a 5V system; touch GND anywhere and your gauges are dead.

There are solid-state voltage reduction devices, 7805 or LM340-5, others, that reduce an input like 12V to a constant 5V. Total cost if you did it yourself probably $3. I just made a pair Monday and Tuesday, and will try them out tomorrow, Thursday.

I have both fuel gauge and temp gauge wired up to use 5V.... I will know soon.

I'll post 5V regulated power supply to this on-going build:
http://www.jeep-cj.com/forums/f98/build-new-set-gauges-scratch-22266/

This is exactly what I have been thinking about trying.
There are probably thousands of different ways to reduce 12 volts to 5 volts.
A common cig-ltr to USB adapter would be another simple way.
Seems to me it would work if you connect the 5volts straight to the A terminal and don't hook anything to the I terminal.

 

[DHugg]

I had wondered when one of us would discover a use for one of these programmable micro processors. I keep thinking fuel injection/ignition control. well done on your project.

IO, I was reading some sensor stuff using the Arduino last night; thinking about bending, pressure, vibration, all of which have application in the steering and drive train area. The razor-thin line between possible and impossible is widening fast, and the definitions of the two terms is blurring.

There are already ethernet add-on boards that WIFI data from one spot to another. With sensors mounted to the drive train, one could send collected data from the collector by WIFI to an in-Jeep system to collect and store for later analysis.

But first I need to find out if my gauges will work. I already know that Crown gauges have different size screws on the backs, and none of the nuts in my considerable stash will fit; both thread spacing and diameter of the screw shafts are different from OEM. How hard does it have to be to get that simple "replacement" criterion right?

 

[IOPort51]

What do we know about HUD, heads up display.

http://bwongtech.blogspot.com/2013/02/how-to-build-hud-for-your-car.html

 

[DHugg]

What do we know about HUD, heads up display.

Bill Wong Tech: How to Build a HUD for your Car

IO, going from the 1960's F-4C Phantom II to the F-15 or F15 with a HUD was the fighter pilot's equivalent of arriving in Heaven. No longer did you have to drop your eyes, refocus and accommodate to lower light levels, find the information from somewhere in the cockpit, then look back outside and hope you could find the Bad Guy you were looking at before the sneak peek.

For a Jeep HUD (doable) we would need to be sure the information always present was worth the trouble to acquire and present heads-up. Also helpful in my humble opinion would be a switchable view to one or more little cameras like the high-dollar vehicles have (in junkyards everywhere, just waiting for us). Jeeps don't have the greatest rearward vis, and my neck complains loudly every time I am backing my boat.

I like your idea!!!