Reserve tank

[soulsurfer52]

This is probably the ultimate newbie question. I just bought an 85 Max and the reserve tank and regular tank are not marked which side is which. I know dumb question and i searched on here but couldn't find anything. Thanks

 

[bikedave99]

No worries man, here is how it works. There is no actual reserve tank, only the main tank under the seat. There is a sensor in the tank that tells the fuel pump controller when their is only .8 (ish) gallons left. The fuel pump controller then turns on the red low fuel light in the instrument cluster and begins to intermittently shut off the fuel pump. This causes the bike to surge and sputter and guarantees that you realize you are real close to pushing your 800lb behemoth home. When you flip the switch on the handlebar from on to reserve, you are forcing the fuel pump to run normally again. Don't forget to flip the switch back when you get gas!

Hope this helps!

 

[soulsurfer52]

Awesome thanks that helps alot

 

[shorthair88]

Well said dave, BTW welcome to the 85 club soulsurfer....

 

[RaWarrior]

I believe to the right is on, and to the left is reserve, if that's what you were asking.

But yeah, there is no "reserve", when the sensor detects it's low, it cuts power to the fuel pump to make sure it gets your attention. Switching to reserve over-rides the sensor and restores power to the pump.

Temperature effects when the light comes on. The sensor is a thermistor, which only conducts when it gets hot. There's always a bit of current being run through it, but the fuel acts like a heat sink and it never gets hot, and never completes the circuit. When the gas level gets below the level of the sensor, it heats up, and completes the circuit, simultaneously tripping the low fuel light, and cutting the pump. So in really cold weather the light can take a lot longer to come on(or not at all), and it really hot weather it might come on sooner.

 

[Rollie]

Is there a way to test that sensor ? Mine will sputter when " on " and full of gas , switch to " reserve " and it will run fine down to the bottom of the tank. Switch back to " on " and it runs o.k. for maybe a minute and starts to sputter again. Switch to reserve and it runs fine again. So for the present I'm running " reserve " all the time.

 

[RaWarrior]

Sounds like the sensor is shorted, but usually when those sensors go bad, they are permanently open, not closed. Then your reserve "wouldn't work", when it started to sputter, you would be totally out of gas.

Is your low fuel light always on?

I believe ohm specs are in the service manual for the sensor.

 

[Rollie]

Agree , I think the sensor is bad , but the light hasn't come on ( may be 'cause I'm afraid of running out of gas on the road so I don't let it get low enough to come on ) . When it first started acting up , sputtering , it was totally out of gas. No light came on and no gas was in the " reserve " either. Put gas in , turned to " on " , it ran fine for about a mile or so and started sputtering. Flipped it to " reserve " and it got me home. Been running it on " reserve " from fill up to guesstimate of 85 miles. No problems.

 

[naughtyG]

Your problem is most probably a blown low fuel light bulb. Can you see it come on when you start the bike?

Replace it and see what happens..

 

[soulsurfer52]

Thanks shorthair

 

[Rollie]

Your problem is most probably a blown low fuel light bulb. Can you see it come on when you start the bike?

Replace it and see what happens..

Nope,

Does not come on when starting. That light bulb would cause it to stumble and quit on me with gas in the tank in the " on " position ? Switch to " reserve " and it goes like stink again. :bang head:

 

[Max1139]

Your problem is most probably a blown low fuel light bulb. Can you see it come on when you start the bike?

Replace it and see what happens..

Gonna borrow this thread and say THX,
didn't know light was to come on when turning key on, doh!!
glad I woke up today for I learned something new!!:eusa_dance:

ok, back to original thread...........

 

[ColoNat]

unk:hurrah for another 85 rider!

i didn't know the light was supposed to come on at startup, either. have occasional similar problems as Rollie - plenty of gas in the tank but will sputter and die unexpectedly until i switch to reserve, but sometimes i can switch back to on later and it will stay running... can debris, i.e. rust in the tank cause a short in this sensor? still fighting with a little of that until i can epoxy it this winter... :confused2:

 

[twistedmax]

Pushed the bike bout 1/3 mile tonight:bang head:, light on at 87miles out of gas at 89 miles:bang head: :ummm:. didnt want to screw with it to much so I pushed it to the nearest station and filled her up, took 3.060 gallons. Came home and looked up the proper way to use the reserve switch (now I know for sure)
thank you VMAXFORUM.:worthy:

 

[sdt354]

Pushed the bike bout 1/3 mile tonight:bang head:, light on at 87miles out of gas at 89 miles:bang head: :ummm:. didnt want to screw with it to much so I pushed it to the nearest station and filled her up, took 3.060 gallons. Came home and looked up the proper way to use the reserve switch (now I know for sure)
thank you VMAXFORUM.:worthy:

Been there done that Rick, and it sucks.
A nice guy,but on a custom, home made chopper(rigid frame) stopped and gave me a ride to a gas station. I kissed the ground when I got off of it. Walked back to my bike (didn't want to hold him up if ya know what I mean) and swore to never let it happen again.Run out of gas that is.
Steve-o

 

[ninjaneer]

-1 on pushing the bike. did this just last week for 1/2 mile. but the problem wasn't user error, but because the reserve switch wasn't electrically closing the circuit that re-energizes the relay. errrrrrrr. ended up cleaning the contacts. emptied a full tank with the switch on "RES" to make sure it worked. yay!

 

[Fire-medic]

-1 on pushing the bike. did this just last week for 1/2 mile. but the problem wasn't user error, but because the reserve switch wasn't electrically closing the circuit that re-energizes the relay. errrrrrrr. ended up cleaning the contacts. emptied a full tank with the switch on "RES" to make sure it worked. yay!

On my other Yamaha (FZR1000) this year I had an intermittent fuel pump operation, I traced it to an internal break hidden by the insulation. I cut it clean in-half at the break, stripped it, piece of heat shrink tubing, soldered it, insulated it & it restored the power just fine. "Clickety-click" until the bowls fill.

A Dremel is a good tool for the contact cleaning, they have all-shapes of brushes & you can get cheaper ones at Harbor Freight. Solder, don't just crimp!

 

[SpecOps13]

Mine was caused by a bad lamp socket and / or bad connection on the back of the dash... Good Luck...