Building a replacement GL1500 Low fuel sensor


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virgilmobile
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Building a replacement GL1500 Low fuel sensor

Postby virgilmobile » Sun May 06, 2012 2:21 pm



My 88 low fuel indicator does not work.The thermistor is $40 or so to replace.
Can I do better? Well I'll try..
First problem,the thermistor doesn't work well with LED's.
Second,when working,the warning lamp kinda glows,maybe working,maybe not.Ends up just being annoying.
My solution...A float switch...Magnetic reed switch,and a simple circuit to flash the light.The flashing circuit is just a add-on and not required.
It does however reduce the occasional lamp flash when the low fuel is getting close.
Attachments
This is my original attempt.The float is a old gl1100 fuel level float
This is my original attempt.The float is a old gl1100 fuel level float
The hand made one kept sticking.It needed to be larger in diameter and length,but can be hand built.
The hand made one kept sticking.It needed to be larger in diameter and length,but can be hand built.
Went to the pull-a-part and selected these floats.cost $5 each
Went to the pull-a-part and selected these floats.cost $5 each
The best fit came from a 99 honda civic.I cut all the excess off.
The best fit came from a 99 honda civic.I cut all the excess off.
This is the final choice and mount.
This is the final choice and mount.
The actual wires
The actual wires
The schematic.It takes 1.5 seconds of full switch contact to get the 555 to flash the light...A natural switch de-bounce circuit too.
The schematic.It takes 1.5 seconds of full switch contact to get the 555 to flash the light...A natural switch de-bounce circuit too.



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WingAdmin
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Re: Gl1500 Low fuel circuit saga.

Postby WingAdmin » Sun May 06, 2012 6:40 pm

Excellent idea using the brake reservoir float. Will the float be impermeable to gasoline over time, do you think?

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Re: Gl1500 Low fuel circuit saga.

Postby virgilmobile » Sun May 06, 2012 7:05 pm

I'm keeping my fingers crossed.I submersed it on gas for 3 days and it does resist brake fluid so I don't expect any problems.I'll get a good feeling for how it works as I burn the miles off but pre-tests show good results.I can bounce the float quite a bit and the circuit won't flash the light.it has to hold a ground for at least a full second before it fill fire off.
Now on to my next idea.Forced air flow helmet.It's 92* and 86% humidity,the helmet is leading me to near heat stroke.

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Re: Gl1500 Low fuel circuit saga.

Postby WingAdmin » Sun May 06, 2012 8:46 pm

virgilmobile wrote:I'm keeping my fingers crossed.I submersed it on gas for 3 days and it does resist brake fluid so I don't expect any problems.I'll get a good feeling for how it works as I burn the miles off but pre-tests show good results.I can bounce the float quite a bit and the circuit won't flash the light.it has to hold a ground for at least a full second before it fill fire off.
Now on to my next idea.Forced air flow helmet.It's 92* and 86% humidity,the helmet is leading me to near heat stroke.


They have them new (OEM) on Amazon for $39.

Brake reservoir cap
Brake reservoir cap


How did you set the trip point for the remaining fuel where it lights the indicator? Or did you just install it and are waiting to see at what point it lights up? :)

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virgilmobile
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Re: Gl1500 Low fuel circuit saga.

Postby virgilmobile » Sun May 06, 2012 10:05 pm

The price is right.There may also be other "off the shelf" floats that will fit the bill too.
I positioned the switching point about 1/2' above the original thermistor junction position.
I was thinking,the original was suppose to warn you when there was 1 gallon of fuel left.Well,that's 34 miles in my case.I added just a little more.
I wanted a bit more warning,maybe 60 miles.It was just a guess.I'll have to carry a couple of gallons with me when the time comes to find out exactly.

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Re: Gl1500 Low fuel circuit saga.

Postby WingAdmin » Mon May 07, 2012 10:33 am

virgilmobile wrote:The price is right.There may also be other "off the shelf" floats that will fit the bill too.
I positioned the switching point about 1/2' above the original thermistor junction position.
I was thinking,the original was suppose to warn you when there was 1 gallon of fuel left.Well,that's 34 miles in my case.I added just a little more.
I wanted a bit more warning,maybe 60 miles.It was just a guess.I'll have to carry a couple of gallons with me when the time comes to find out exactly.


Instead of running out on the road, I originally determined when it came on by taking the output of the pump off the fuel filter and putting it into an empty gas can. I then ran the pump until the low fuel light came on. I stopped it, put the output into a new empty gas can, and started the pump again until it ran dry. That told me exactly how much I had left. I then just poured the fuel back into the tank.

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virgilmobile
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Re: Gl1500 Low fuel circuit saga.

Postby virgilmobile » Mon May 07, 2012 11:06 am

Oh sure...You'd do it the safe way. :lol:
I guess it would be less adventurous than running out of gas on the road and hearing about it from HER the rest of the month. :)
Good idea tho.I suppose it would be better knowing before the bike dies while avoiding oncoming traffic with a blinking light.
Thanks for the tip.

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Re: Gl1500 Low fuel circuit saga.

Postby WingAdmin » Sat May 19, 2012 11:35 pm

I liked your idea, so I built the circuit tonight, and cut down the Civic float. I didn't have a .47uF cap sitting in my box, so I used a 1uF instead - the flash is a bit slower than yours, but it will do. I'll pull my fuel pump tomorrow and stick it in!

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Re: Gl1500 Low fuel circuit saga.

Postby virgilmobile » Sun May 20, 2012 12:29 am

I just verified...My light blink when the fuel gauge is right near the bottom of the white marks,before it gets to the red zone and is a daytime attention getter.I also measured 1.4 gallons before the vapor run(1 mile) so I estimate 50 miles or so after the light till coasting.A little more than the original 1 gallon warning.It's just there is often way more than 35 miles till the next gas station here.

I downloaded a 555 timer circuit program.You plug in the knowns and it will give you the variables.Change from a .47 to a 1 and lock the output and it will show the resistors needed.

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Re: Gl1500 Low fuel circuit saga.

Postby WingAdmin » Sun May 20, 2012 1:15 am

I marked where the thermistor was before I removed it from the mount, I'm going to try to adjust the float to go off somewhere similar to that, perhaps a bit higher. I'll run the fuel pump into a gas can until it comes on, then run it into a second gas can to see how much remains, so I get an exact idea.

I had already soldered in the 470K resistors when I realized I didn't have the cap. I have an app on my phone that includes a 555 calculator, but I figured I'd just stick the 1uF in there and see what it did, and if it was too slow, I'd look at changing the resistors. Turned out OK, so I'll leave it as is. :)

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Re: Gl1500 Low fuel replacement sensor

Postby WingAdmin » Mon May 21, 2012 12:33 pm

I put my new float in last night. I took your idea of a fabricated top mount along with the original lower mount:

Low fuel sensor float
Low fuel sensor float


However, I found that even with the lower mount as low as I could get it, I still couldn't get the float to actuate at less than about two gallons - at which point the fuel gauge hadn't even reached "E" yet.

So I did away with the lower mount altogether. I replaced the circlip on the bottom of the float that it came with, and used that to prevent the float from coming off the sensor. I also sunk a self-tapping screw through my upper mount and into the plastic of the top, to make sure that it wasn't going to come loose and float away (making sure the screw did not puncture the sealed inner tube, however). I then bent the upper mount to move the float assembly lower.

I put the assembly in the tank, connected the output of the pump to a hose, and put the other end of the hose in a gas can. I then turned the ignition on and connected the fuel pump to +12V. I let it pump gas out of the tank until the low fuel light started to flash. At that point I disconnected the pump, put the hose into an empty gas can, then reconnected the pump and let it run until it ran the tank dry. I could then measure the amount of gas it had pumped into the second gas can, to see how much my "reserve" was. I would then adjust the float assembly up or down as needed, pour the gas back into the bike, and try again.

I got it so that when it started flashing the low fuel light, I had exactly one gallon left, which was my goal. I buttoned it all up, and called it complete. I love your solution virgil, and it seems to work perfectly. I'm going to move this thread into the DIY section for anyone who wants to try it in the future.

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Re: Gl1500 Low fuel replacement sensor

Postby virgilmobile » Mon May 21, 2012 12:55 pm

Thank you for the consideration.
My float triggered at a slightly different level but it was a 'test mounting best guess' anyways.
I don't mind the little extra fuel after the warning light.Mine is at 1.4 gallon.
Just 3/4" lower mount would even it out to 1 gallon.
So it's one of those "adjust if necessary" things.
At least it works every time and the light is noticeable.
The magnet reed switch has it's own range of "hold" so,on mine when it started to flash,it didn't cut on and off.It just popped on and stayed there till I filled it back up.

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Re: Building a replacement Gl1500 Low fuel sensor

Postby WingAdmin » Tue May 22, 2012 7:15 am

I noted that while backing my bike out of the garage with it right at the "light just coming on" level, the sloshing around caused it to flash/not flash a couple times. But I wouldn't expect to see it do that while riding on the road.

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Re: Building a replacement Gl1500 Low fuel sensor

Postby virgilmobile » Tue May 22, 2012 9:44 am

I suspect as much.You could also think of it as a pre-warning flash. :)
My flasher circuit takes a full second of grounding to start the light flashing which buffered any bouncing of the float.On the road,it just came on and annoyingly blinked at me all the way to the gas station.
Either way....it's a whole lot better than nothing and watching the trip odometer and calculating estimated distance before you have to push it to the gas station.

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Re: Building a replacement Gl1500 Low fuel sensor

Postby WingAdmin » Tue May 22, 2012 10:04 am

virgilmobile wrote:I suspect as much.You could also think of it as a pre-warning flash. :)
My flasher circuit takes a full second of grounding to start the light flashing which buffered any bouncing of the float.On the road,it just came on and annoyingly blinked at me all the way to the gas station.
Either way....it's a whole lot better than nothing and watching the trip odometer and calculating estimated distance before you have to push it to the gas station.


Mine is a good second as well (remember I've got the larger electrolytic in there). I've thought multiple times of putting a flow sensor in the fuel line going to the carbs, and running it to my "Bike PC" to use as a fuel totalizer, like in an airplane. I could then grab the speed pulse going to the radio to determine the speed of the bike, and from that work out an instant MPG readout....but I don't think I care that much. :)

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Re: Building a replacement Gl1500 Low fuel sensor

Postby virgilmobile » Tue May 22, 2012 10:52 am

A guy asked me the other day what kind of mileage my 88 gets.

Not really knowing for sure,I told him it's better than my truck but hastened to add that economy is not the reason I ride it.

I've know I've burnt more gas getting to the Waffle House on the bike than in my 96 Explorer.

It's odd too...in the truck it's 3 miles one way..
On the bike it's 87 miles one way. :D
Maybe I should check the Tom Tom again.

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Re: Building a replacement Gl1500 Low fuel sensor

Postby SgtCharlie » Tue Mar 19, 2013 11:07 pm

virgilmobile wrote:I've know I've burnt more gas getting to the Waffle House on the bike than in my 96 Explorer.

It's odd too...in the truck it's 3 miles one way..
On the bike it's 87 miles one way. :D
Maybe I should check the Tom Tom again.


ROTFLMBO!!! Ain't that the truth! Worst thing I ever did was buy a reload rig for my pistols! Now I spend 3 times what I used to shooting! (I shoot 10 times as much!)
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Re: Building a replacement Gl1500 Low fuel sensor

Postby Mag » Wed Mar 20, 2013 9:37 am

Everything on the bike is a "backroads ride".....really appreciate the old highway instead of the freeway we have here.

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Re: Building a replacement Gl1500 Low fuel sensor

Postby SgtCharlie » Wed Mar 20, 2013 11:56 pm

Mag wrote:Everything on the bike is a "backroads ride".....really appreciate the old highway instead of the freeway we have here.


Yep! Good ole' Route 66! I love the old "backroads"!
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Re: Building a replacement GL1500 Low fuel sensor

Postby ronjr123 » Fri Oct 03, 2014 1:53 pm

I assume you guys placed the timer on some small bread board. How did you make it waterproof?

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Re: Building a replacement GL1500 Low fuel sensor

Postby WingAdmin » Fri Oct 03, 2014 3:00 pm

ronjr123 wrote:I assume you guys placed the timer on some small bread board. How did you make it waterproof?


Yes, I made mine on a small piece of perfboard. I then encapsulated it with a hot glue gun to make it waterproof. Not pretty, but it works.

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Re: Building a replacement GL1500 Low fuel sensor

Postby khspe2 » Sun Oct 12, 2014 9:49 am

I just finished building and installing this sensor. A couple of notes if you are going to do this:

1. Before building and installing this sensor, I had already replaced my instrument panel lights with LEDs per Wingadmin's how-to article. If you have installed the low fuel LED and resistor (as described in Winadmin's ho-to), the build for the flash is simpler. Virgilmobile confirmed that the flash circuit build only requires what is on the left hand of his screen shot of the circuit (in grey). The circuitry on the right side of the screen shot is not required.

2. Before installing the sensor in the tank, verify that the sensor works appropriately. Use an ohmmeter to check for proper operation. I had purchased a faulty switch and did not even know.

3. Check to ensure that the donut float actually floats in gasoline. These floats were originally designed for brake fluid, which is more dense than gasoline. When I went to the junkyard, I brought a cup of gasoline to test the floats, and to my surprise not all of them floated. I do not know if a change was made in model years for the Honda floats, but is is possible that the floats were re-designed to be a density between gasoline and brake fluid.

4. In order to protect the flash circuit, I cast it in polyester resin. This will surely protect it from the elements, and it looks cool, too.


Now all I have to do is the fine tuning as to where the light starts blinking.

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virgilmobile
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Re: Building a replacement GL1500 Low fuel sensor

Postby virgilmobile » Sun Oct 12, 2014 11:59 am

I also tested the float in gas for a day to confirm it was ok before I installed it in the tank.
The one I got worked fine.I am surprised to hear that some do not float.Hmmmm.
Did you note what it came out of.?
Are you gonna post some pictures too.??
Sounds like you've done a great job.!!




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