puzzling electrical glitch

Hello ST fans! I finally get to buy the St1300 of my dreams...kind'of. An 05 with 70k mi. on the clock but she seems to be in good shape and running well.
My problem is a strange couple of electrical bugs: #1): a unreliable fuel gauge (I almost ran out one the first long run!!!) and #2) and somewhat relevant is a trip odo that wants to reset to zero...randomly!
I've been a rider for 35 years. We had mechanical speedos and odo's and no gauges at all before. I would be fine with a known mileage per tank but I can't even do that with out a calculator now !

Is this a known issue (with a simple kluge fix) or a problem with this particular bike?

Thanks for any feedback!

There's plenty of threads here about the anomalies of the fuel gauge. Best bet, when you get down to one flashing bar get gas. I find that the mileage remaining value shown is pretty accurate only if you DO NOT turn off the engine. If you do that the bike likes to assume you have more gas than you do.

As far as the odometer that resets to zero, does this happen after first starting the bike? is so, usually this is a sign that your battery is weak and near its end of life...

FYI - 320 miles you are sucking fumes. I refill every 250 miles. Weak battery will also reset the clock. Hopefully the odometer is holding up.

VFRedrider said:

#1): a unreliable fuel gauge (I almost ran out one the first long run!!!)

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We can give you better answers if you can clarify what you mean by "unreliable." If you've done one long run and ran it down to fumes, I'd chalk that up to misinterpreting what the fuel gauge is telling you. Two bars means it's time to look for gas, one means it was time to look for gas half an hour ago and anything less than that means you've got a good chance of running out if you insist on pressing on.

If you're seeing something like the gauge suddenly dropping to one blinking bar from, say, half a tank, that's a known, curable problem.

I've been a rider for 35 years. We had mechanical speedos and odo's and no gauges at all before.

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...and a litany of other things I could live a long, happy life without, like breakable mechanical speedo and clutch cables, unbelievably primitive fueling, lackluster brakes, low-capacity electrical systems and having to ride it barefoot, uphill both ways in the snow.

I would be fine with a known mileage per tank but I can't even do that with out a calculator now !

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The 1300 isn't a bike that gets x miles per gallon no matter how you ride it; there are a lot of factors that have an effect on it, many of which come into play at freeway speeds. I usually say this in response to complaints about the throttle being jerky, but it applies to fuel economy, too: this bike rewards excellent right-hand technique and penalizes you if you don't get it right. I've had mine for twelve years and can pretty much predict what my range is going to be based on the kind of riding I'm doing. The way I ride, there's a difference of 12-13 MPG between all-city and all-highway riding. On a bike where there's 7+ gallons between fuel stops, that translates to a difference of about 90 miles.

#2) and somewhat relevant is a trip odo that wants to reset to zero...randomly!

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It's probably not random even if it looks that way. The clock and trip odometers (both of them) reset when the system voltage sags below what's required to maintain them. It's either happening while the bike sits or, more likely, when you run the starter. Either is an indication that your battery's had it. Put a voltmeter on the battery and start the bike; if you see anything less than 10 while the starter's running, it's time for a new one. Nobody's ever had a failure in the reset button, and if it were a software problem, we'd have seen it by now.

--Mark

Thanks for the replies!

I hadn't considered the battery being low. It seems to start well. Cranking is what I'd expect. The lights don't dim excessively while cranking either. Given that the clock is also resetting regularly (or irregularly...), I'd say you've got it diagnosed!

Regarding the fuel guage, the issues are
#1) riding along with 2 bars thinking about getting gas on a desolate stretch of 205 in Norcal to a flashing last bar in about 10 miles. I then put 6 1/2+ gallons in and
#2) starting a 50 mile Sunday ride with 4 bars, parking on the side stand at the top of the hill after 45 minutes, got back on 30 minutes later to have NO BARS and reserve bar flashing. Again slight panic...it was down hill to get refueled fortunately. The thought of pushing the beast didn't sound too good. 10 corners later, the gauge was back in the middle at 3 bars. I was thinking stuck or sunk float.

I'll chalk it up to learning curve. I don't hate new tech but, a reliable odo with a re settable trip worked pretty well in the dark ages. My 02 VFR didn't have any glitches. There is a whole lot more going on with this motorcycle...and I like it!

VFRedrider said:

Thanks for the replies!

I hadn't considered the battery being low. It seems to start well. Cranking is what I'd expect. The lights don't dim excessively while cranking either.

I'll chalk it up to learning curve. I don't hate new tech but, a reliable odo with a re settable trip worked pretty well in the dark ages. My 02 VFR didn't have any glitches. There is a whole lot more going on with this motorcycle...and I like it!

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If your headlights don't dim very much while cranking, you DO have an electrical glitch of some kind. They should dim a lot - as in switching OFF while the starter is engaged. That could be related to the clock and odometer resetting to 12 am and zero. I would have to look at the Service Manual to tell you where it is, but the headlight relay could be a problem.

VFRedrider said:

I hadn't considered the battery being low. It seems to start well. Cranking is what I'd expect. The lights don't dim excessively while cranking either. Given that the clock is also resetting regularly (or irregularly...), I'd say you've got it diagnosed!

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Definitely check how much it sags during starting. There's a normally-closed pole in the starter switch that interrupts the headlight circuit when you press it, so they shouldn't be on at all while you're on it.

#1) riding along with 2 bars thinking about getting gas on a desolate stretch of 205 in Norcal to a flashing last bar in about 10 miles. I then put 6 1/2+ gallons in

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I wrote the page I linked to, and to be honest, I've never had a firm handle on whether it's supposed to go two, one, blinking or straight from two to blinking. (And most times I forget to notice so I can correct that page.) The thermistor in the lower tank goes dry at just over a gallon, so adding 6.5 gallons sounds like that part of the system is working just fine.

#2) starting a 50 mile Sunday ride with 4 bars, parking on the side stand at the top of the hill after 45 minutes, got back on 30 minutes later to have NO BARS and reserve bar flashing. Again slight panic...it was down hill to get refueled fortunately. The thought of pushing the beast didn't sound too good. 10 corners later, the gauge was back in the middle at 3 bars. I was thinking stuck or sunk float.

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A few people in the early days of STs found out that hard way that if you stick a fuel nozzle far enough into the tank, you can damage the float arm, so it's possible something's amiss there. If you're down to one bar, the upper tank is completely empty, and you can raise it to remove the sender from underneath for inspection. While you have it out, test its resistance, because that's an uncommon-but-not-unheard-of failure.

--Mark

Thanks again for the replies Mark!

I put a volt meter on the battery and it dropped to 8.6 so, I'm sure your spot on with your diagnosis. I noticed that MC battery mfg's don't date code their products. First thing I look at regarding batteries is age.

The STwiki page was most informative and explained the somewhat erratic action on the gauge. The logic make some sense although the application may be a little suspect. With a functioning trip odo, I should be able to confidently work thru a tank. If the gauge is showing something different than the mileage would suggest, I will believe the odo first! 250 to 300 miles pending riding conditions should be easy to keep an eye on.

I can tell the number of quality contributors on this site will be good reading and great resources.

Thanks again!

Blrfl said:

...never had a firm handle on whether it's supposed to go two, one, blinking or straight from two to blinking.

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Regardless of the designed intent, the observed behavior on mine is straight from two steady to one blinking.

I feel as though I get 5.5 to 5.75 gallons/fill with two bars showing, and about 6.25 gallons into the tank after it starts flashing one bar. I don't usually stop and fill the *instant* it drops to two bars, but generally after it's been there a while and I have lately gotten lazy and waited for it to start flashing one bar at me before taking action.

Mark is spot on about the difference in fuel economy connected to the type of riding. Commuting I get in the 37+/- range (according to the display), since I have a relatively short trip and lots of alternating waiting and acceleration cycles. On a weekend day-long ride, it climbs to around 44 - 45 mpg on the display.

I plan on about 240-260 miles / tank when commuting (240/6.25 = 38.4 mpg) , closer to 290-300 (290/6.25=46.4 mpg) when I'm out having fun. I ALWAYS reset the "A" trip and the average fuel economy readouts at a fill. The "B" trip odometer I generally disregard unless I am on a multi-day ride and I want to have a handy total trip mileage accumulator.

Get that battery sorted out then start wearing out the new one.

Here is a good battery that works well in the ST http://www.ebay.com/itm/Motobatt-Battery-For-Honda-ST1300-A-P-1300cc-03-13-/171926006575?hash=item280796ab2f:g:ncwAAOSwLqFV8C2h&vxp=mtr

VFRedrider said:

I put a volt meter on the battery and it dropped to 8.6

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This is interesting about the odometer trip resetting. This just happened 2 weeks ago to my wife's 2008 VFR800. Then after a fuel fill the bike didn't start, acting like a bad battery. Got it started by pushing and got it home for some testing. When I checked the battery it came out good. It charges, holds a charge and tested okay at the dealer for CCA. Cleaned the connections and reinstalled. What I found was that the battery was not charging while the bike was running. I was getting 11.68 to 11.86 volts at idle and at 5k rpm. This led me down a different path test the charging system and all connections along the way. In my case the stator was bad and had to replace.

I am not saying that this is the same as your issue but for me a couple of things came out of this besides having to replace the stator. I learned how to trouble shoot the charging system on this bike, discovered that the ohm check on the startor is not a good check at all, you must check the stator voltage while it is disconnected from the RR and while the bike is running. All three leads must be close in voltage readings. Mine were 47.6, 47.8 and 16.7. One of the three phases of the stator has failed and needed to be replaced. The ohm check said that the stator was good. Because all plastic was off I went through all visible connections and cleaned them up.

Grabcon said:

... you must check the stator voltage while it is disconnected from the RR and while the bike is running.

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Doesn't work on the ST because the alternator is completely self-contained and the only place you could test that is on the bench after major surgery to get it out. Fortunately, they don't tend to fail often.

--Mark