smprince1 Posted June 7, 2009 Share Posted June 7, 2009 When I fill the gas tank on my bike, the top two bars of the LCD gauge don't light up. When there are two bars showing (tank near empty and usually when I would refill the tank on my old R1100RT), the tank will only accept 4 gallons. Anybody experience similar problems? How can I diagnose whether the problem is in the sending unit in the tank or in the LCD display? Thanks. Link to comment
philbytx Posted June 7, 2009 Share Posted June 7, 2009 You might THINK you've filled it up but the tank has a goodly amount of "air space" above the filler neck. If you get anal, you can SLOWLY fill 'er up so that all the bars are on the RID. I just fill up to the neck, "BurP" the tank once by moving the bike on the centrestand fore and aft, then top off. I just reckon on running it 240 miles then filling it up...... Link to comment
ron c Posted June 7, 2009 Share Posted June 7, 2009 The fuel level sending unit goes through a plug together connection under the right side of the gas tank. When this connection gets dirty the gas level display will show less fuel available. Try cleaning that connection to restore good electrical contact. Regards, Ron C. Round Rock, Tx. Link to comment
Tom R. Posted June 7, 2009 Share Posted June 7, 2009 For quite some time, it has been difficult to get a completely full reading on my 2003 RT. There may be some value to what Ron says here about cleaning the electrical contacts where the sending unit plugs into the harness under the right side of the fuel tank. As part of my recent fuel pump replacement, I cleaned those contacts pretty good and seem to see a completely full reading more readily now. However, I also noticed some dark discoloration at the top of the arc on the sending unit contact board. I did not attempt to remedy the discoloration. Link to comment
smprince1 Posted June 8, 2009 Author Share Posted June 8, 2009 Thanks for the suggestion to clean the contacts. I'll do that the next time I have the side panel removed. What do you recommend to clean them with? Link to comment
11101110 Posted June 8, 2009 Share Posted June 8, 2009 Try CRC contact cleaner, it is what I use. You can also use DeoxIt which is good stuff too acutally better but cost a lot more. Link to comment
Boffin Posted June 8, 2009 Share Posted June 8, 2009 For quite some time, it has been difficult to get a completely full reading on my 2003 RT. There may be some value to what Ron says here about cleaning the electrical contacts where the sending unit plugs into the harness under the right side of the fuel tank. As part of my recent fuel pump replacement, I cleaned those contacts pretty good and seem to see a completely full reading more readily now. However, I also noticed some dark discoloration at the top of the arc on the sending unit contact board. I did not attempt to remedy the discoloration. Tom, the sender on the pump module is only for the low-level warning light. The fuel contents guage is a seperate unit at the front-top of the tank. This is a common issue and is usually doen to dirty contacts. The exception is that on US market bikes, it is possible for the evapoprative emissions system to become pluggedleading to a partial vaccum in the tank. This in turn can cuse the tube with the fuel level float to collapse limiting travel of the guage - either showing fuel in an empty tank or not showing the full contents. Go for a longish ride, stop and open the gas tank whilst listening for air being sucked in. If nothing else, you get to go for a longish ride... Andy Link to comment
John Dickens Posted June 8, 2009 Share Posted June 8, 2009 In the end it can also be a faulty sender unit. Mine went intermittent a couple of years back and no amount of contact cleaning makes any difference. The sender unit is the 'dip tube' type and is on the right hand side of the tank under the tank top cover. Unfortunately you still have to access the connectors through the fuel filter access panel so the tank still has to come off to change it. Link to comment
Edgar Posted June 8, 2009 Share Posted June 8, 2009 I had the very same issue with my LCD showing 2 bars low on a complete fill up. The problem went away when I, for testing purposes, removed the plumbing from the charcoal canister. Next time you have the panels off, try plugging the vacuum line at the throttle bodies, and disconnect the breather line from the tank to the canister. Link to comment
tomk99r11 Posted June 8, 2009 Share Posted June 8, 2009 My bar accuracy also improved when I removed the cannister. The light stays on which I will address the next time the tank is off. Link to comment
scottgr Posted June 9, 2009 Share Posted June 9, 2009 My gauge has always read one bar low after fill-up. Last year I did a canisterectomy because it was clogged and pulling a vacuum on the tank. No change. Then, feeling guilty about the environment, I bought a good used charcoal canister and reinstalled the emissions stuff. No change. I think it could be the float, but I've decided to just live with it. Link to comment
PCHRT Posted June 10, 2009 Share Posted June 10, 2009 You might THINK you've filled it up but the tank has a goodly amount of "air space" above the filler neck. If you get anal, you can SLOWLY fill 'er up so that all the bars are on the RID. I just fill up to the neck, "BurP" the tank once by moving the bike on the centrestand fore and aft, then top off. I just reckon on running it 240 miles then filling it up...... +1 there is a lot of room past the filler neck that does not get any fuel. When fueling after hitting the filler neck i giggle the bike on the center stand and can get in excess of .5 gals. That's another 20 - 30 miles depending. There are threads also where some owners have drilled holes into the filler neck (removing it first) in order to vent out that air and give a true 'full' tank. Link to comment
swgee Posted June 11, 2009 Share Posted June 11, 2009 Mine would do that every now and then after a fill-up, usually just one bar though. The problem, at least with me, was not filling the tank up all the way. Mine will take fuel till it almost overflows and then it slowly goes down and I repeat this until the fuel levels off about halfway or maybe a little more up the neck. Laziness or impatience prevails most of the time and I end up shorting myself a half gallon or so and therefor the not-quite-full, fuel indication. Scott Link to comment
PCHRT Posted June 11, 2009 Share Posted June 11, 2009 yeah everyone probably wonders why i'm shaking the bike so long for???? it's amazing how much it fills up the neck and goes down, I must look a little funny at the pump. It's even the case with the 08 GT. Link to comment
John in NC Posted June 11, 2009 Share Posted June 11, 2009 The problem is the contacts on the connection right side by the fuel tank. Pull the plug and clean the contacts then coat with dielectric grease. I do this every time I have the fairing off. I was the same way (anal) about trying to get my tank full and the consequences were that the fuel expanded and went to the canister and plugged it then created the vacuum in the tank. A lack of atmosphere in the tank along with pressure from the fuel pump on the hose attached to the pump caused the hose to blow off. No fuel, no start. Link to comment
ShovelStrokeEd Posted June 11, 2009 Share Posted June 11, 2009 If you are talking about the connector on the right/outside/lower portion of the tank, that is for the O2 sensor. The connections for the fuel pump and fuel sender are under the tank. Link to comment
appoirier Posted June 12, 2009 Share Posted June 12, 2009 1997 R100RT 105'xxx Mi Fill her up, shake...top it off, gives me "full" otherwise -1 bar. Link to comment
SAAB93driver Posted June 12, 2009 Share Posted June 12, 2009 On my RS my gauge would always go to full on fill up until I replaced the fuel filter, then I lost the top bar. Every once in a while (2 times per year maybe) the top bar will come back but only briefly. I tried the cleaning contacts thing but that didn't help. It shouldn't be that way and it annoys me but I learned to live with it. Link to comment
AndyS Posted June 12, 2009 Share Posted June 12, 2009 When there are two bars showing (tank near empty and usually when I would refill the tank on my old R1100RT), the tank will only accept 4 gallons...... The tank is no where near empty with 2 bars still showing. As for the top two bars being shy, well an awful lot of these bikes are like that. Certainly for 1 bar anyway. Even when the tank is absolutely brimmed it is often hard to keep that top bar lit for long. So, like Philbtx says, are you sure you have it full? Moreover does this gauging issue worry you that much that you are prepared to take all the Tupperware off and start fiddling around underneath the plastic? I suggest you learn YOUR bikes idiosyncratic fuel gauging read back and live with it till you really need to tear into the underwear! ;-) Andy Link to comment
Ken H. Posted June 12, 2009 Share Posted June 12, 2009 You might THINK you've filled it up but the tank has a goodly amount of "air space" above the filler neck. If you get anal, you can SLOWLY fill 'er up so that all the bars are on the RID. I just fill up to the neck, "BurP" the tank once by moving the bike on the centrestand fore and aft, then top off. I just reckon on running it 240 miles then filling it up...... +1 there is a lot of room past the filler neck that does not get any fuel. When fueling after hitting the filler neck i giggle the bike on the center stand and can get in excess of .5 gals. That's another 20 - 30 miles depending. There are threads also where some owners have drilled holes into the filler neck (removing it first) in order to vent out that air and give a true 'full' tank. Yes, and then people wonder and complain about why their charcoal canisters get contaminated. The fueling level restriction is there for a purpose – to leave venting space in the tank. Shish... Link to comment
philbytx Posted June 12, 2009 Share Posted June 12, 2009 As it warms gasoline expands by volume (not weight) so THAT is the reason manufacturers tell you not to top off your tank. BMW (and other mfrs) have this designed into their gasoline tanks which is why we have the space in ours. I only ever fill up ("burp") my tank when I'm going OUT on the road. When I top off to put the bike away, I don't get anal as my garage gets awfully warm in TX summers! Link to comment
GMC Posted June 17, 2009 Share Posted June 17, 2009 Had my bike in for service this last month, throttle cable(s) replacement. When i went in, i had the same symptoms as many in this thread, with never being able to indicate full on the gauge, but still having many, many miles to go with only 1 bar showing. Been that way for years. With no work specifically done to the fuel quanity system, but presumably just the removal of the tank and moving stuff around, i now have the opposite problem: Shows full when full, but shows 3 bars when the fuel light is about to come on. Haven't tried the suggested fixes here, as of yet, but sounds like vacuum cannisters/suction, and some resultant or possibly unrelated physical damage to the tube could be at fault. Curious to hear if anyone has had this same odd reversal of the fuel quantity indication issue. Up to the reversal of the issue, I figured I had it pegged from what i've read here. Presumably all part of same problem, but an interesting twist? Link to comment
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