Building a replacement GL1500 Low fuel sensor


Step-by-step tutorials on how to maintain and fix your GL1500
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MikeB
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Re: Building a replacement GL1500 Low fuel sensor

Post by MikeB »



Oh, that is not good. If it wasn't for your dislike of the OEM system, you could have saved money by getting an OEM replacement sensor. They are less than $60.

Of course, when you do get it all ironed out, you will have the satisfaction of knowing you made a super modification to your fuel sensor system.


MikeB
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Erdeniz Umman
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Re: Building a replacement GL1500 Low fuel sensor

Post by Erdeniz Umman »

virgilmobile wrote: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.
You could use a thermistor from Mouser p/n: 527-2004-1k, with a price of $1.49.

http://www2.mouser.com/ProductDetail/Am ... u6fA%3D%3D
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MikeB
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Re: Building a replacement GL1500 Low fuel sensor

Post by MikeB »

Erdeniz Umman wrote: You could use a thermistor from Mouser p/n: 527-2004-1k, with a price of $1.49.

http://www2.mouser.com/ProductDetail/Am ... u6fA%3D%3D
That's true and I have done that. I am pretty sure I have some spare thermistors here somewhere but not 100% sure where they are. I think I ordered 10 each several years ago. I would have looked for them and offered them to Kiptap but he hates the OEM low fuel sensor setup.
MikeB
1998 - GL1500 w/184,500 miles ~ 2017 - GL1800 w/13000 miles
USAF Avionics Communications Tech - 1968 - 1986 / Flight Engineer C-130E - C-141B - 1986 - 1992. Retired
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kiptap
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Re: Building a replacement GL1500 Low fuel sensor

Post by kiptap »

kiptap wrote: UPDATE:
OK, I just looked at pricing a new unit and here is my mistake, I purchased a Dorman brand and not an OEM Honda brand, I didn't even think about it honestly. The reviews/complaints are showing a substantial number of failures, about 20%, usually after a month or longer. The complain is "light stays on all the time". I guess I violated the cardinal rule of not buying Honda. So am going to not going to fiddle around with it anymore, I'm just going to get a HONDA unit and swap floats. Expensive lesson.
OK, The final passage in the saga of the low fuel sensor. It works great! I had to replace all of the float unit instead of swapping floats as the Honda float is just a bit smaller and wont fit on the Dorman reed switch shaft. Then I had it mounted too low and ran out of gas after 22 miles. I moved it up a bit and ran out at 41 miles. Good to go for me. Its been in the tank under gas for about two weeks total now and it works great. Just one or two partial activation's while stopping and then its all on and flashing. I got to say that flashing really does raise your anxiety while running for the nearest gas station even with 40 miles left.

So I guess advise to others is to make sure you get an OEM unit or you may have issues. Anyway, I'm super happy with the change over, thanks virgin & admin for the concept.
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curtm
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Re: Building a replacement GL1500 Low fuel sensor

Post by curtm »

Has anyone used the thermistor from Mouser p/n: 527-2004-1k, with a price of $1.49. method, and would it be ok exposed tp gas or does it require encapsulation
Curt
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Erdeniz Umman
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Re: Building a replacement GL1500 Low fuel sensor

Post by Erdeniz Umman »

This video may help.


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khspe2
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Re: Building a replacement GL1500 Low fuel sensor

Post by khspe2 »

About two years ago, I built a new low fuel sensor using Virgilmobile's build. It took two attempts to get it to work properly. For the first attempt, I used a reed switch fabricated from a junkyard Civic brake fluid switch, but discovered that the float part of the switch did not float in gasoline. For the second attempt, I purchased a Civic brake fluid switch that was manufactured by Dorman. I verified that it floated in gasoline and installed it. It worked as anticipated.....

....for about two years. Lately I noticed that the low fuel light would not go out after filling the tank. So I took it apart and low an behold the float portion of the switch no longer floated. It must be absorbing gasoline somehow.

After much research, I discovered that the specific gravity of DOT 4 brake fluid is close to 1.06, whereas the specific gravity of gasoline is about 0.7. Theoretically water should float on top of brake fluid, but I have not confirmed this. I believe that the effective specific gravity of the Civic float is most likely somewhere between 0.7 and 0.9. If the float absorbs gasoline, the effective specific gravity of the float will approach the specific gravity of gasoline, thus preventing the switch from properly performing.

The solution was simple: find a switch that has an effective specific gravity less than 0.7 by a reasonable amount to ensure proper reed switch operation. Here is what I found:


According to the data sheet, this switch has an effective specific gravity of 0.50


The switch body is stainless steel, and the float is BUNA-N, which is not soluble in gasoline. The switch is about the same size as the Civic switch and mounted easily in the same mount originally crafted by Virgilmobile for his switch. Here is a picture of the switch installed on the fuel pump assembly:


I used a piece of fuel line to act as a buffer between the mount and the switch, also because the threads on the switch are pipe threads!

The switch costs more than the one that Virgilmobile used, but after two failures, I was willing to pay a little more for a more durable solution.

If you use this switch, keep in mind that all connectors for the wires need to be gasoline resistant. This means do not use shrink tubing, and remove the plastic cover on terminal ends if you use them.
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4given
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Re: Building a replacement GL1500 Low fuel sensor

Post by 4given »

Many thanks to Virgil and Scott from way back in 2012 and now to khspe2 in his recent post. I also tried two different Honda Civic floats. One was made by Dorman and the other was an OEM float purchased from Honda. They both failed. The first one failed when the stem warped and wouldn’t allow the float to move up or down and OEM also failed when the stem swelled and wouldn’t allow the float to move.I’m not sure where Virgil and Scott purchased their floats but they must have been made of better material back in 2012. Then I read the post by khspe2 and purchased the stainless steel switch by Innovative. So far after a little tweaking it is working great and when the light goes on I have just north of 45 miles to get to a gas station. Many thanks to all who contributed to this topic.Pictures to follow.
Attachments

Dorman
Dorman


Civic OEM
Civic OEM


Stainless by Innovative
Stainless by Innovative



“Fight the fight and do what is right“
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Re: Building a replacement GL1500 Low fuel sensor

Post by WingAdmin »

4given wrote: Thu Jul 23, 2020 1:42 pm Many thanks to Virgil and Scott from way back in 2012 and now to khspe2 in his recent post. I also tried two different Honda Civic floats. One was made by Dorman and the other was an OEM float purchased from Honda. They both failed. The first one failed when the stem warped and wouldn’t allow the float to move up or down and OEM also failed when the stem swelled and wouldn’t allow the float to move.I’m not sure where Virgil and Scott purchased their floats but they must have been made of better material back in 2012. Then I read the post by khspe2 and purchased the stainless steel switch by Innovative. So far after a little tweaking it is working great and when the light goes on I have just north of 45 miles to get to a gas station. Many thanks to all who contributed to this topic.Pictures to follow.
Mine was OEM Honda, that came from RockAuto. I suspect something has changed in the materials used to make them...Glad to hear that you got something that works, however!

I have mine calibrated to light when I have exactly 1 gallon remaining. When I see the light come on, I assume that means "30 miles to empty" which still gives a little bit of wiggle room.
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Tim 1956
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Re: Gl1500 Low fuel circuit saga.

Post by Tim 1956 »

WingAdmin wrote: 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. :)
You people scare me. Years ago I modified CB radios and worked on electronics and never did this. I always experimented. Not the scientific brain. ;)
Tim


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