[WrathMXer]

Very interesting. Thanks for the update. Subscribed.

 

[Clarustnb]

So the end result was a full replacement fuel pump? ebay has them for about $85. Looks like I'll be just using the trip meter from here on out. till x-mas.

 

[GT6Racer]

Sorry for the delay - been busy !!!
First how it works : The thermistor is a device which changes resistance with temperature, with resistance dropping as temperature increases. As it is a resistor, it generates heat, which in turn reduces its resistance, generating more heat etc etc... When the thermistor is inside the fuel, the heat dissipation to the fluid is high enough that it exceeds the heat being generated by the thermistor and hence its temperature is stabilized at a certain level. However, when the fuel is low, and the thermistor is in air, the heat dissipation rate decreases, such that the thermistor starts to increase temperature. The fuel light works by putting the thermistor is series with a set resistance in order to deliver a designed current to the dash when the thermistor resistance ( as dictated by its temperature) rises above a defined value.
Measurements : Using a potentiometer in place of the thermistor it was possible to deduce that the light will come on when the thermistor resistance is below 160 ohms. By measuring the voltage drop over the potentiometer at various values it was possible to deduce that on the bike the thermistor is in series with a resistor of 116 ohms. What has happened to my stock sensor was that it was still generally working, but did not drop resistance far enough, hence the light did not come on.
Challenge : need to find thermistor which will provide the correct characteristics : resistance in fuel > 160 ohms, resistance in air < 160 ohms, but beyond this must have high resistance in fuel to avoid big constant current draw, and must be such that it doesn't go unstable ( heat up excessively) when exposed to air. Thermistors are defined by their B value, but generally also share their dissipation constant in air, and the current they will accept. Using this it was possible to build a system model, calculating resistance and hence heat generation, as well as the heat dissipation rate when in or out of the fuel. Of course, it is also somewhat important to make sure that the thermistor in air does not exceed the fuel auto-ignite temp, or the max temp permitted by the thermistor.
Result : using published properties, and knowing something of the application, I was able to select the Honeywell 135-202FAG-J01 with B value 3468K and dissipation in air of 2.5mW/degC. The nice part of this thermistor is that it is glass encased, and hence not affected by the fuel as I suspect the stock ones are. Cost was a whopping $1.47 a piece.
Testing : Bench testing was completed with 12v and a series resistor of 116 ohms to confirm that the thermistor selected responds as expected, and then I fitted it to the bike ( but not in the tank) and confirmed function by testing in and out of fluid. The fuel light worked as expected. As the worst case for the thermistor is when it is dry, I ran the thermistor in air for 24 hours constantly, and all seemed fine. However, this is as far as I got and never fitted the thermistor to the bike. I will when my light fails next time. To fit it, I'll need to dismantle the stock sensor, and fit the new thermistor in place of the old one.
BTW - note that the thermistor is mounted inside a can which has only small holes in it, such that the thermistor response is slowed and the light doesn't go on/ constantly when the fuel level is near the switch level.

So that's the status - the design is done, but not yet tested. Try it at your own risk !




Sent from Motorcycle.com Free App

 

[craighjr]

Awesome data thanks. Saving me a ton of time.

 

[freezer16801]

awesome. I seem to have hit the final straw at least twice this year. The first time was a trip through a nice mountain road running out of fuel twice while looking for a single gas station. This made my spring day off, day trip a PITA. Second was running out of gas on my way home from work on the first freezing day of the year, 1 mile from home at 3:30 am. I had to push my bike for 3/4 mile in riding boots.

I am constantly cautious of my fuel level and I still ran out of gas at least three times this year.

 

[TBlaze21]

If the whole fuel pump only cost $85 then why would you just buy the thermister for $151 which is included in the fuel pump?

 

[craighjr]

An eBay pump is $100 with no guarantee. From Ducati the pump is propbably a grand.

 

[shaunmed]

99 oct. gas here in the UK is $8.56 a US gallon...

you people should revolt, seriously. if gas was $8/ gallon in the US I guarantee there would be a revolution.

 

[Drinky]

you people should revolt, seriously. if gas was $8/ gallon in the US I guarantee there would be a revolution.

We pay around $9,20/gallon here. I remember being in the States a few years back when gas prices went up to $3,40/gallon and everyone was outraged. Here it would be pure bliss :abduct:

 

[hypermo]

Thanks to GT6Racer the 82 cent repair is working great so
far. Having a lightweight flywheel, stacks, Termi 2 into 1
and a heavy right hand and no low fuel light is a bad
thing. My wife has has to bring me a gas can a few times
now. The Thermistor is a 163.00 part from Ducati and
they have tried to make it a non repairable part but
with a little work it can be repaired.

The Thermistor is in a small metal can attached to a
metal post strapped to the fuel pump. It is attached
to one wire at the bottom of the can held apart from
the can by a fiber disc. The 2nd attachment is to the
metal can by a small hole in the top of the can. The
bottom wire attaches to a plastic plug the 2nd wire
attaches to the mounting screw for the metal can and
then to the same plug completing the circuit.

You have to pry out the fiber disc at the bottom of the
can the edges of the can are bent over locking it in.
The solder joint at the top of the can needs to be
released to remove the other end of the Thermistor.

The green wire at the bottom of the can runs into
a brass tube that was soldered onto the wire then
crimped onto the end of the Thermistor. This broke
when I tried to undo the crimp so I just soldered
the wire onto the Thermistor. The small brass tube
is still in the fiber disc but broke just after it exits
the fiber disc that is were it was crimped.

The attached pictures show the original Thermistor,
the new Thermistor the broken piece of the brass
tube. Also they show the Thermistor can and mount
and the plastic plug. And my now working fuel light.

 

[Spex]

Great info, @hypermo. It would've come in handy for me earlier when I was considering fixing my fuel warning light, but now I've taken to riding with a 12L fuel bladder in the tailback if I'm needing to stretch between service stations.

That said, I'm hoping to (finally) get around to stacks at some point so I might revisit the thermistor then.

 

[hypermo]

Great info, @hypermo. It would've come in handy for me earlier when I was considering fixing my fuel warning light, but now I've taken to riding with a 12L fuel bladder in the tailback if I'm needing to stretch between service stations.

That said, I'm hoping to (finally) get around to stacks at some point so I might revisit the thermistor then.

I am looking into a fuel bladder or a fuel bottle to carry in my kreiga tail pack
as well. I was thinking of removing the stacks and going with the Ca Cycle
Works larger tank, but They are to much fun the sound and the way they wake
up the bike are addicting. With the lightweight flywheel and the stacks the
bike spins up much faster and low end torque seems the same.

Its so nice to have the light working again and but its no cure for running
out of gas if your far from a gas station. But its nice to not have to guess
when it is going to happen the light comes on find gas now.

The Thermistor was 82 cents the shipping was around $5 so I bought
4 of them. I just could not justify paying $163 for a 82 cent part in a
metal can with 2 wires and a plug from Ducati. And if you buy a used
fuel pump off E-bay you have no idea if the Thermistor is good or how
long it will last. And like the other poster it just bugs me when something
on the bike is broken.

Again thanks to GT6Racer for doing all the work and testing he is that one
that made this fix possible.

 

[UroTard]

Thanks for all of the info guys. I have a CA-cycleworks tank and my fuel light crapped out on me late last year, so i will be looking into this fix.

hypermo: any chance you'd want to sell one of those extra thermistors? Could probably fit in a plain letter envelope with some clever padding

 

[PhilBoncer]

Ca Cycleworks 6.4 Gallon Hypermotard Fuel Tank | ca-cycleworks.com

Yup.

This was going to be my suggestion.

PhilB

 

[hypermo]

This was going to be my suggestion.

PhilB

Only problem with that is no Stacks with the big tank and the bike
is more of an animal with the stacks it is a night and day difference.
For the few times I need to be that far away from gas its just not
worth it for me I will carry some extra fuel. The Hyper is for me not
a touring bike at all its pure hooligan all the way.

I mostly ride the mountain roads I am only 5 mins from them and
with a working fuel light, I should be fine as it was never a problem
before it quit working.

 

[hypermo]

Thanks for all of the info guys. I have a CA-cycleworks tank and my fuel light crapped out on me late last year, so i will be looking into this fix.

hypermo: any chance you'd want to sell one of those extra thermistors? Could probably fit in a plain letter envelope with some clever padding

I already gave 2 away i am going to hang on to the last one just in case.
I plan on keeping the Hyper for a long time and may need to do this again.
Just search for the Honeywell part # GT6Racer posted they are available
from many sources and are inexpensive.

 

[PhilBoncer]

OK, yes, usage matters. If I had an HM, I'd be using for everything, like I do with my Monster, and thus the big tank would be the indispensible part. My M900 has a working range of about 200 miles, and that's a good quality.

The main reason I haven't, and wouldn't, buy an MV Agusta Brutale is that it gets about 25mpg, and thus has a 100-mile range at best. I testrode one, and it was a delightful bike, but I can't hang with having to stop and fill it up every day to get to work and back.

The low fuel light on my Monster hasn't worked in many years; it just wasn't worth it to spend the money and hassle very two or three years to fix it again. I just use the tripmeter, like an oldschool bike. Turn it to zero when filling up, fill it when the meter gets to the miles or the bike's useful range.

PhilB

 

[hypermo]

OK, yes, usage matters. If I had an HM, I'd be using for everything, like I do with my Monster, and thus the big tank would be the indispensible part. My M900 has a working range of about 200 miles, and that's a good quality.
PhilB

200 miles that is fantastic If I am lucky I get 100, average in the low to mid
90's. That's mostly my fault though the Hyper is a weekend toy stress relief
and on the mountain roads its on or off the gas no cruising.

I tried using the trip meter but got caught a couple times when your in the
groove and having fun I forgot to keep an eye on it. It's no fun when you
twist the grip coming out of the corner and instead of the front wheel lightly
lifting you loose power because your out of gas. Both times I was less than
20 miles from home 5 to 10 miles from a gas station.

I actually took the stacks off rode the bike for a month w/o them because
I was going to by the 6.4 gal tank but just couldn't do it. I am looking for a
small 3-7 liter fuel bladder just a small backup for the rare times I may be
out for a long ride away from gas.

I see with the miles you put on your bike how fuel range would be a primary
concern for you. I will be lucky if I put even a 1/4 of the miles on my bike
that you have on yours.

 

[PhilBoncer]

Getting used to the tripmeter method takes some practice to be reliable at. I started riding in the mid-1980's, on bikes from the 1960's to early 1970's, and back then no bikes had fuel gauges or lights. It was tripmeter and manual fuel tap, and that's just how you did it. So that's how I learned, and I'm used to that.

My bike is primary transportation. I haven't even owned a car for transportation since 1988. I've been to 35 states on this Monster. I'm a consulting engineer, so I work on job projects all over the country, and I usually ride to the job site in whatever state it's in, and and ride my Duc daily while there. Last month I rode down from where I'm working now in St. Louis MO, to the MotoGP in Austin TX; the trip down was a single 900-mile day. A sub-100-mile fuel range would have made that considerably more of a PITA.

I do like to testride bikes whenever I can, to keep up with the tech and for fun, and to think about what I might get someday when (if) I am done with my Monster. Or if someone someday builds something enough better for me to make me jump. I've tested more than 70 bikes in the last few years. The HM1100S, your exact bike, was one of only two so far that has been a serious temptation to switch. I seriously considered it. It's the most fun bike I've ever ridden (although my recent testride on a KTM 1290 SuperDuke was pretty darn close), and the one thing I determined I would need on the HM to make it work for me was that fuel range. If my Monster gave up the ghost tomorrow, a first-gen HM1100S (with a CACW tank) is still on my shortlist as to what I'd get next.

Have fun; that's what it's built for.

PhilB

 

[Spex]

I've had the engine cut out twice at around 130km (about 80 miles in your money), but they were two unusual stints when I was doing a lot of commuting through stop-go traffic. Over time and many tanks' worth of experience, I've settled on a 'safe' refuelling range of around 150km, which usually leaves a reserve of at least 30km worth in the tank. I suppose it's easier that I don't commute anymore, so my fuel consumption is a bit more predictable.

When I'm carrying a fuel bladder, I take it all the way to 180km which is sketchy - sometimes there's enough left in the tank that I can't get the whole 12L in, sometimes I have to stop and refuel early because it starts cutting out before I hit 180km.