Fuel Gague Adjustment

Micksan

Supercharged
Joined
Nov 16, 2010
Messages
448
Location
Del City Ok
Ride
2023 Triumph R3 GT, 2022 Moto Guzzi V85TT,
I just got this R3 and it came with a add-on fuel gauge mounted on the handlebar. Looks nice>>>BUT<< . I have noticed that it was going down a lot faster than I expected. Last night I noticed that it was just about to go into the low warning red zone. Filled it up and it took 3.4 gallons.
Having ridden BMWs for a lot of years I am familiar with the gas float system. Only thing I am hoping is that someone kept their install instructions and could share them with me. I have to pull the tank to change out the fuel filter. ( Has 30K same filter) .
Also will this gauge void out the feed me light ( low fuel light) ???
Thanks
Russ in OKC
 
Thanks but can not seem to get past their registration. Real touchy
 
Low fuel light fix with pictures.

Well I finally got a hold of a banged up tank that I could cut apart and use to recalibrate the low fuel light/ fuel gage. Take a look at the following pictures to see how the fuel sending unit works and how the fuel pump assembly sits inside the tank.



In the below picture you can clearly see the fuel level sending unit. This is how it basically works. As the fuel level goes down the fuel level float descends into the tank. The float is attached to a thin silver colored rod, the other end of the rod is attached to the fuel level sending unit. As the float sinks in the tank it causes the aluminum piece on the sending unit that you see in the photo to rotate slightly clockwise. This causes the sending unit to put out a higher voltage. Where this voltage is sent to I really don’t know but when the voltage reaches 2.3 volts or so the low fuel light will eventually come on. At least that's what mine did.

One of the things that I discovered was that the fuel level float will not rise at all when there is 1.25 gallons in the tank, which unfortunately was the most fuel I could get into the tank without it starting to flow over the cut edge of the tank. What this means is that if you want a working low fuel level light and if you could get the sending unit adjusted just right you would have at least 1.25 gallons left when it comes on. Which is exactly what I was looking for. I want about 35-40 miles worth of fuel in the tank when the light comes on not the normal 80 or 90 miles as it seems to be set from the factory. The pictures below show the fuel level with 1.25 gallons in the tank.



I also learned that the bike will run just fine with just .25 gallons left in the tank. Or at least it will run when it’s level and not moving. This is a picture showing my bike doing just that. I once ran the tank down to the point that the bike would stall when I hit the brakes hard as I was entering a gas station. When I filled the bike up, the tank took 6.056 gallons. So I think it is safe to say that the maximum useable amount of fuel that can be carried in the tank is right at 6 gallons.

Something else that I discovered was that the amount of voltage that comes from the fuel level sending unit varies depending on what else is powered on and if the bike is running. Example, if you take a reading of the sending unit’s voltage then pull the fuse for the headlights the voltage will rise quite a bit. Also the reading will be different if the bike is running. All these factors will affect what voltage the sending unit is putting out and I would guess at what point the low fuel light will come on. I was fortunate enough to have a tank that I could use to adjust the sending unit float level while the bike was running. This allowed me to recalibrate the sending unit to be the most accurate and get as close as possible to my goal of having 1 gallon of useable fuel in the tank when the light comes on.

If you would like to recalibrate your low fuel level sending unit read on and look at the pictures. Keep in mind I am not a motorcycle mechanic so use this information at your own risk. Nothing about this is all that hard to do but be careful. Gasoline is very flammable and I don’t want anyone crying to me if they burn down their house, burn up their bike or turn themselves into a crispy critter. A spare tank is not required but it does help for absolute accuracy. Although absolute accuracy is what you want, any adjustment will more than likely be an improvement to what you have now, even if it isn‘t perfect. Also keep in mind that you are going to be working on a very expensive part of your bike, the fuel tank. A new tank retails between $716.00 and $860.00 depending on the color and if it's two tone. If you damage yours by dropping it, denting it or even scratching it you will not be a happy camper. Ask yourself, is the risk worth the reward?

Before you begin go to your local Triumph dealer and buy the following items.
1each: Seal, Fuel Pump. Part Number T2400447. About $15.00
2 each: Washer, Banjo, M12 Part Number T3550128. About $3.00 for both.
You may be able to get buy without buying these but for $18.00 it is probably worth not taking the risk of having a fuel spill at 70 MPH. You are also going to need a digital voltmeter, so beg , borrow or go buy one at radio shack. They aren’t all that much money and they are nice to have around the garage.

First thing you want to do is siphon out as much gas from the tank as possible. You wont be able to get it all but the more the better. Hopefully you didn’t just fill it up.

Next prop up your tank which is explained in your owners manual.


Now remove the electrical connector and unbolt the fuel hose from the bottom of the fuel pump assembly . The bolt for the hose is 18mm.

Mark then remove the two thin hoses that are on the bottom of the tank. One hose is the filler neck drain hose, the other goes to the charcoal canister. You don’t want to mix them up when you reinstall them.
 
Remove the 8mm bolt that holds on the bracket that secures the two thin hoses to the tank.

Now remove the long bolt that secures the rear of the tank to the frame. You can now pull the tank away from the bike and set it upside down on a soft towel.


Remove the 9 nuts and 9 washers that secure the fuel pump to the tank.

Warning! Warning! Warning! Be very careful at this point. If you just yank the fuel pump assembly out of the tank you are going to be running back to the Triumph dealer and be $70.00 bucks poorer, in order to buy a new fuel level sending unit. And if they don’t have one in stock, which is almost certain, you’ll be waiting a week for them to get it in. Take a look at the picture below. You can see the black fuel level float and the silver rod that attaches to it, if you aren't careful the float is going to get hung up on the lip of the tank as you pull the pump assembly out. Use a bent coat hanger wire to grab hold of the float and pull it up toward the pump assembly. You can then grab it with your finger and pull it through the hole. Once the float is out of the tank, the whole assembly will easily pull right out.

With the fuel pump assembly out at the tank, you can clearly see everything that is included in the assembly.

Now take the whole fuel pump assembly back to your tankless bike. Place a towel between the two frame members and sit the assembly on the towel. Disconnect the electrical connector that is just above the fuel pump so the fuel pump isn’t running while you are making the adjustment. Now reconnect the electrical connector to the bottom of the fuel pump assembly. And so you wont run down your battery remove the 20 amp fuse for the headlights.

Take the negative lead of your digital voltmeter and attach it to something on the frame so it will be grounded. Now attach the positive lead to the white wire of the four wire connector . See the pictures below. Go ahead and turn the bike’s ignition switch on. You should see that your voltmeter is reading 2.5-2.8 or so volts. If you don’t, check that you have your voltmeter set properly and that the meter's leads have a good contact to the frame and the white wire. If your voltmeter is reading a voltage, raise and lower the fuel level float. You’ll see that the higher the float is raised the lower the voltage output will be. If you have a fuel gage on your bike you’ll also see that the fuel gage will slowly move up and down as the fuel level float is raised and lowered.
 
What you want to do now is find out what voltage is required from the sending unit to trigger the low fuel light to come on. Lower the float until the reading on your voltmeter is 2.0 volts. Place a screwdriver or some other object under the float so the voltage will stay at 2.0 volts and let it sit there a minute. Then slowly lower the float bit by bit until the low fuel light comes on. This is a bit of trial and error but very important if you want to get it right. On my bike I discovered that the low fuel light would come on when the voltage was at 2.3 volts but it doesn’t come on instantly upon reading 2.3 volts. It takes a little while, maybe 30-60 seconds. I would suggest you find the voltage that will cause the low fuel light to come on then turn the ignition off and then back on again. If the low fuel light is now off, let it sit a couple of minutes with the ignition on. If it still remains off, you need to lower it just a tad and let it sit for a minute or so, keep doing this until the light comes on.

Once you know the accurate voltage that will cause the low fuel light to go on, it is a simple matter of bending the rod that is attached to the float so that the voltage reading that will cause the low fuel light to come on, wont read that voltage until the float is resting about 3/16 of an inch above the black fuel pump assembly seal. The reason you want that 3/16 inch gap between the seal and the float is to compensate for the thickness of the tank which has a raised lip where the fuel pump assembly mates to the tank. If you fail to take this gap into account, you might have a low fuel light that will never come on. Take a look at the below picture, as the unit comes from the factory the float rod is straight as can be. As you can see in the picture my recalibrated rod is just slightly bent. A little bit of bending goes a long way in adjusting the sending units voltage output.


Once you have made your adjustment disconnect the four wire connector from the bottom of the fuel pump assembly and reconnect the electrical 2 wire connector for the fuel pump. Remove the old fuel pump assembly seal and install the new one. Once again a word of caution, when you go to install the pump assembly into the tank be careful with the fuel level float. You have to turn the assembly at an angle then gently force the float into the tank. Also notice that the fuel pump assembly angles off to one side, if you try to stick it in going down the center of the tank you are going to break something expensive.

Once you have the assembly in the tank put the 9 washers on the 9 studs followed by the 9 nuts. Tighten down the 9 nuts using a torque wrench set at 5 NM using a crisscross pattern. Now remount the tank on the bike and install the fuel hose using the 2 new aluminum crush washers. Torque the banjo bolt to 15 NM using a 18mm socket. If you don’t have a 18mm socket a ¾ inch socket will do. Reconnect the 4 wire connector on the bottom of the fuel pump assembly. Reconect the two thin hoses to the bottom of the tank and bolt the hose bracket to the tank. Lower the fuel tank and bolt it down. Reinstall the 20 amp headlight fuse. If the tank was completely emptied add 1 gallon of gas so when you turn the ignition on the fuel pump isn’t running without fuel.

Now the moment of truth, turn the ignition on, hopefully the low fuel light is on. If it isn’t let the bike sit a minute or so with the ignition on. If it still isn’t coming on you got a problem. Your choice is to take it all apart again and start over or you might be able to stick something through the filler neck and bend the float slightly up.

Update.

I just went through my first full tank of fuel since doing the recalibration and these are the results.
The low fuel light came on at 166 miles. And it took 4.53 gallons to fill the tank back up. With this tank of fuel I got 36.6 miles per US gallon, which was mostly highway miles doing 65 to 75 mph. If I got 36.6 mpg and if there was 1.47 of usable fuel still left in the tank, that means I could go another 53.8 miles before I would run out of gas.

My goal was to recalibrate the low fuel light/gas gage sending unit so I would have 35-40 miles worth of gas in the tank when the low fuel light came on. So it appears that the best I could do was almost 14 miles more than my goal. Oh well, I can live with it. It is certainly better than the 90+ miles that is left in the tank, as the thing comes set from the factory. It is my belief that this is about as well as the sending unit can be recalibrated and still have a low fuel light, that works. The problem is that the fuel level float bottoms out on the tank belly while there is still quite a bit of fuel still left in the tank and there is no way of making the float sink lower as the remaining fuel level decreases. Overall I am very pleased with the results of the recalibration.

For those of you who have a fuel gage on your bike, like I do, you may be interested to know that the fuel gage works much better now that I have recalibrated the sending unit. Prior to the recalibration, at about 90 miles the fuel gage would read ¼ full. Here are the results after the recalibration. The fuel gage now stays pegged at full for the first 30 miles. At 66 miles the fuel gage reads ¾ full. At 96 miles it reads ½ full. At 125 miles the fuel gage reads ¼ full. And at 166 miles the gage read empty just as the low fuel light comes on.

I hope my efforts help everyone who has been frustrated by this problem that Triumph has so far, not been willing to address. Hopefully they have cured this problem on their new touring model that comes with a fuel gage from the factory, standard.
 
I just got this R3 and it came with a add-on fuel gauge mounted on the handlebar. Looks nice>>>BUT<< . I have noticed that it was going down a lot faster than I expected. Last night I noticed that it was just about to go into the low warning red zone. Filled it up and it took 3.4 gallons.
Having ridden BMWs for a lot of years I am familiar with the gas float system. Only thing I am hoping is that someone kept their install instructions and could share them with me. I have to pull the tank to change out the fuel filter. ( Has 30K same filter) .
Also will this gauge void out the feed me light ( low fuel light) ???
Thanks
Russ in OKC


Russ,

There's also a tune the dealer can run that will make your fuel gauge much more accurate. It was a quick warranty fix for me, so I'm not sure how much something like that would cost otherwise.

The low fuel light on my R3T now comes on at about 40 miles. And I have tested it. It’s fairly spot on!

Dan
 
Biker1059, thanks for the in depth "show and tell" concerning the fuel sensor and adjustments. I may not run into this again as my eventual purchase of the R3T will not have the same tank set up but I appreciate the step by step procedure with the pictures that will undoubtedly help someone else out in the future.

Good job.

Dennis

14 dtg KAF
19 dtg Dubai
20 dtg London
22 dtg Ace Motorcycle Cafe

73 dtg Dubai
74 dtg Home (Thunderbird time and, hopefully, R3T ordering time)
 
I have 50000 miles on the same filter as the old saying goes "out of sight out of mind" or something like that.:D

I got interested in the filters after I helped change a few clogged ones on BMW K bikes. Nor to bad for those because you could take off the gas capo assy , and reach down to get at it.Still alongside the road not much fun. Then came the oil heads. They decided to come up with a plan to mount the filter outside of the tank. On those you had to remove the tank. The Moto Guzzi Riders followed suite.
All of the above bikes have suffered clogged filters . Pick up a little dirt here and then there . Next thing you know your riding along and your bike feels like it is running out of gas, and then shuts down.
To me it is easioer to change it out at home on a nasty rainy day , rather than have to get a tow truck to take me to a shop some place.
So far I have not had the problem , just stopped and helped some folks that did.
 
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