| Author | Message | ||
     Xodot |
I took my 08R in for warranty work and mentioned the low fuel light (LFL) comes on when the bike and the ambient temperature is cold. They don't get a lot of Buells in the shop up here so the service manager contacted HD tech support. He told me he was told the following: the fuel level sensor is a temperature sensor build into or onto the fuel pump. the sensor compares the temperature of the ambient air, the frame and the fuel. Now I would like to figure out how this low fuel sensor could work. If the air temp sensor and fuel temp sensor is the same cold temperature, (like +5C for example)does the "brain" figure the low fuel sensor is no longer submerged in gasoline since there is no difference in temperature, and kicks out the LFL warning. This theory could only be true if fuel is always colder than the air surrounding it. Does someone really KNOW how it works? This explanation was news to the service manager and he had no idea how it actually functioned. | ||
| Captain_america |
I get the LFL so often I don't even trust it anymore if it comes on in the morning or at night... I only trust the thing if it comes on and it is warm out | ||
| Jaimec |
A measured amount of electricity is fed into a wire in the fuel. The temperature of said wire is constantly monitored. The program knows how much heat the wire will generate when it is exposed to air, vs submerged in fuel. When the wire reaches a certain temperature, it alerts the computer that there is insufficient fuel to keep the wire "cool" and a warning light (and countdown odometer) is triggered. BMW used this in their first generation K-bikes, but abandoned it in favor of a float device in the tank (which also allowed them to hook up a fuel gauge in later models). If the LFL comes on with the CEL, that's when I ignore it. If it is on by itself, I pay attention (but I also compare it to the miles recorded on my trip meter, too). What is annoying is that even a bogus LFL switches the odometer to "Miles on Reserve" mode and you have to take your hand off he handlebars to toggle it back to where you want it. | ||
| Dennis_c |
Mine works ok from 15f to 70f has not been hoter than that yet for my 1125. My old ULY worked at all temp. from 9f to 100f. I think HD is full of S---. | ||
| Echo15 |
I have noticed mine coming on (and scaring me enough to fill up quickly), but I can only get 2.8 gallons of gas in.... pretty acute with a 5.6 gallon tank. I have always zero'ed out the trip mileage when filling so that I always know about where I am. | ||
| Syonyk |
Mine comes on randomly if it's <32F out. If it comes on when I first start, and I have under 150 miles on the tank, I ignore it. If it comes back on when the bike is warm, and I have 150+ on the tank, I fill up. In warmer weather it behaves. | ||
| Sprintst |
I didn't believe it until I read it in the electrical manual actually, it's a pretty simple thing | ||
| Zac4mac |
I started getting LFL and CEL on cold mornings 2 years ago. Did some measuring myself and found the thermistor sensor was out of range. A few threads here later, I got a couple of e-mails from an anonymous Buell engineer. What we found were 2 failure modes that give a LFL and CEL. 1) LFL/CEL at start-up, both go out when Op-Temp is reached. Solution - replace IC with current Rev firmware 2) LFL/CEL come on when Op-Temp is reached, may go out later, depending on ambient temp. Solution - replace fuel level sensor/pump assembly. Zack | ||
| Andros |
After they replaced my fuelpump the lthe light turned off. It is a faulty sensor in the fuelpump. Youll need to replace the whole pump to fix this. | ||
| Jaimec |
How hard is it to replace the fuel pump assembly? | ||
| Ogobracing |
My approach, just fill the damn thing up if the light comes on. You are soon going to use it up anyway. I will caution everyone, once the light comes on if it is working properly, you need to get gas NOW. The countdown miles or merely a possibility if you are gentle with the wrist. | ||
| Froggy |
Ogob, I've had the light come on 20 miles after filling up on my 09. It works perfect on my 08 regardless of the temp. It comes on reliably at about 4.5 gallons used, and I've driven 32 miles with the light on and still had a little extra remaining when I filled it. | ||
| Syonyk |
Ogob: There's a difference between the light coming on at the proper time (4.3 gal the way I fill it), and the light coming on a gallon down on a cold morning. The one on a cold morning is a false alert. | ||
| Cataract2 |
Eh, I don't get the CEL. Just the LFL. I know when the bike is cold that the LFL could come on at key on. I just wait for the bike to warm up and it goes out. | ||
| Usanigel |
The theory is fact the operation is fiction! A little float would be too easy! | ||
| Zac4mac |
The sensor is no magic. It's a heated thermistor that is cooled by the fuel. When the level drops below the sensor, it heats up and trips the light. The reason to replace the sensor/pump, for me at least, was the thermistor's resistance range changed(drifted) out of the range the IC was programmed for. At that point, the confused IC sets a CEL along with the spurious LFL. Ryan - your symptoms are the same as example 1 above, you need a new IC. Zack | ||
| Cataract2 |
No longer under warranty Zack. Will get a new IC when it's needed. | ||
| Xodot |
I get the same warning as Ryan: A LFL only and NO CEL at start up when cold ambient temps. I have been using the same solution too = ignore the LFL until the bike warms and it goes out. Sent me in panic mode the first few times it happened to me! Since I am still under warranty, I'll let them replace the faulty sensor/pump assembly. Even though it malfunctions, it's still a pretty cool bit of thinking that went into this sensor. Thanks for the explanation of how it works Jaimec! | ||
| Rob_l |
WOW this just happened to me for the first time last Saturday. Cold out, full of fuel, one mile down the road LFL and CEL went another mile and went off. Set B1005 code if I remember right. Hasn't happened again. Dame! what am I in for now? | ||
| Zac4mac |
Rob_l - you are in scenario 2 from above. You should get a new pump/sensor ass'y thru warranty. <edit>Unless you took off before getting to OpTemp... Z (Message edited by zac4mac on April 11, 2011) | ||
| Rob_l |
Zac4mac, it was to Op temp, will wait for it to act up again. Will Mr. dealer warranty the fuel pump just do to the code being stored? Thank you. | ||
| Pizzaboy |
the integrity and reliability of my low fuel light has completely left the building on my 08 about a year ago... ironically shortly after my warranty expired. after leaving me on the side of the road twice, and on the side of the track once, i no longer rely on it, and have accepted it as a unique idiosyncrasy of my buell. instead, i simply reset my trip odometer at every fill-up, then religiously fill up at my next earliest convenience after i hit 150 miles on my tank. problem solved. for track use, i fill up every 3rd session. again: problem solved. (Message edited by pizzaboy on April 12, 2011) | ||
| Syonyk |
Even with a working low fuel gauge, I always reset the trip odometer on every fillup. It's a good backup, and it gives me an idea of how much gas is left. "Can I make it to the top of the mountain and back, or should I fill up before I head out?" I typically fill at 160 miles, but most of my riding is commuting. | ||
| Zac4mac |
Most likely, your dealer's service dept will contact Tech Services. Rob, if you were already at OpTemp and the light set, then went out later, the sensor is the likely culprit, working in "real time". When you get the lights before OpTemp, it's due to the IC's old firmware that continued to monitor sensor inputs (esp fuel level) AFTER shutdown of the bike. The lights are coming on in response to a historic event, not a live one. New firmware doesn't monitor sensors after key-off. Z | ||
| Captain_america |
I get both scenarios... I need a new IC anyway... There is a huge scratch on the inside of it somehow  | ||
| Rob_l |
Thanks Zack, It's only happened one time. Been riding to work daily no problem. Rob | ||
| Xb1200rick |
 Y'all have completely jinxed me . I have only had a false low fuel when it was 45 or colder outside..til now. Soon as this started ,I started having a low fuel even after the bike is warmed up. yesterday I stopped to get gas, bike was already hot, after I filled up the low fuel came on as I pulled away from the gas station. I was fine to let it go since it only happened when it was cold out , but now it is aggravating me Rick | ||
| Pizzaboy |
Y'all have completely jinxed me . I have only had a false low fuel when it was 45 or colder outside..til now. Soon as this started ,I started having a low fuel even after the bike is warmed up. yesterday I stopped to get gas, bike was already hot, after I filled up the low fuel came on as I pulled away from the gas station. I was fine to let it go since it only happened when it was cold out , but now it is aggravating me get used to it. as more and more 1125's get out of warranty, few owners will be interested in spending a LOT of hard earned money on these bikes at the stealership.. especially since parts availability and a non clear solution to the problem are both weak. i still have yet to hear the absolute final answer on what the solution to the low fuel light is after watching this board for the past 3 years, i dont suspect that will change any time soon. i DEFINITELY wont be letting my dealer hold on to my bike while waiting weeks or months for a part that isnt integral to running it in the first place! |
