reserve switch

[Tom]

So today I discovered the reserve switch doesn't work!! On the plus side I did get 400ks before pushing............

[Arnie]

Tom,

You may find that the reserve switch was just in the "ON" position all the time. 
OR, it just doesn't work, as in allows all the petrol to flow out of the tank keeping none in reserve.
In either case, you used all the fuel the tank can hold. :-)
I too, once got to exactly 400kms - and then was pushing.

Cheers,
Arnie

[Jeff0308]

I to found out the reserve never worked........the hard way.........wanted to see where reserve kicked in.... Don't work.... When it reads empty its empty!

[Capn Ron]

I haven't ever tested the "reserve" feature of my '92.  That may be due to it no longer functioning properly, or it may be that I've never let the tank get low enough for the feature to kick in.

Ours uses an electronic "cutout" reserve...That means two cylinders will cut out giving you the impression you're running low on fuel and prompting you to flick the switch to "Reserve."  The owner's manual states the total capacity of the fuel tank as 5.8 US gallons (4.8 Imperial gallons).  It puts the reserve at 1.3 US gallons (1.1 Imp Gal) of that total.  So, at 4.5 gallons used, or between 200 and 225 miles (45-50MPG), I should feel the cutout.

My question is, what triggers the system?  Is it a particular Ohm value on the in-tank level sender?  Is it a fuel gauge needle position?

Cap'n Ron. . .

[NJona86FJ]

G'day.
I'm well curious about this. My 1tx doesn't do that. And I'm even more certain because since I dropped her the reserve switch has been smashed out, I get the red light and nothing else, no cutout just keeps going till empty. Anyone else have a beautiful ambulance that does this? Wondering if I even HAVE a fuel pump!!!!!
Cheers
Neil

[Capn Ron]

G'day.
I'm well curious about this. My 1tx doesn't do that. And I'm even more certain because since I dropped her the reserve switch has been smashed out, I get the red light and nothing else, no cutout just keeps going till empty. Anyone else have a beautiful ambulance that does this? Wondering if I even HAVE a fuel pump!!!!!
Cheers
Neil

Up to the '87 model year used gravity-feed.  '89 through '93 used a fuel pump.

Where do you have a red fuel light?  In the 1993 Australian PDF owners manual (the only one I could find), it shows a low fuel indicator light on the dash in the location where my ABS light is located...  Do non-ABS bikes have this low fuel light?  It should be just below and right of the left turn signal indicator.

Cap'n Ron. . .

[FJmonkey]

My 86' has the low fuel light and it still works. The fuel cut off (Simulated reserve) also worked on my 86' until I upgraded to an 84/85 petcock. The harness and connector is still in place should I ever want that function back. But till I had my FJ I never had a fuel level gage or low warning light. Using the trip meter is instinct for me.

[movenon]

I haven't ever tested the "reserve" feature of my '92.  That may be due to it no longer functioning properly, or it may be that I've never let the tank get low enough for the feature to kick in.

Ours uses an electronic "cutout" reserve...That means two cylinders will cut out giving you the impression you're running low on fuel and prmpting you to flick the switch to "Reserve."  The owner's manual states the total capacity of the fuel tank as 5.8 US gallons (4.8 Imperial gallons).  It puts the reserve at 1.3 US gallons (1.1 Imp Gal) of that total.  So, at 4.5 gallons used, or between 200 and 225 miles (45-50MPG), I should feel the cutout.

My question is, what triggers the system?  Is it a particular Ohm value on the in-tank level sender?  Is it a fuel guage needle position?

Cap'n Ron. . .

I am in the process of cleaning the inside of my tank I have the sender out and it appears that there is a small sensor that I suspect is a simple on/off sensor.
I think this feeds into a circuit going to the 4 prong ignition control connector that plugs into the CDI / Ignitor.

A theory is while the in tank sensor is shorted (on, fuel above the sensor) things are great,  but when it is open (off, fuel below the sensor), low fuel.. It sends a signal to the ignitor to turn off the fuel pump relay voltage thus starving the engine. If you don't reestablish fuel pump power you die..

When you switch on the reserve rocker switch you are simply bypassing the fuel cut off signal and reestablish power back to the fuel pump. ? Be interesting to have a green light on the voltage line going to the fuel pump relay (or fuel pump B+) to test this...    .

I have never liked the wording on the reserve switch. "RES" and "ON".... You would think that "RES ON" and "RES OFF" might make more since, but hey, I am dyslexic most days anyhow.... It would be fairly easy to have the switch set in the wrong position. There again maybe a reserve on light might be helpful.

And as long as things are coming from my head and leaking out into fingers here, they could have taken the space on the 88- 93's where that stupid clock is  and used it for a light or better yet a voltmeter...   Things to ponder.
George

[Harvy]

A theory is while the in tank sensor is shorted (on, fuel above the sensor) things are great,  but when it is open (off, fuel below the sensor), low fuel.. It sends a signal to the ignitor to turn off the fuel pump relay voltage thus starving the engine. If you don't reestablish fuel pump power you die..

When you switch on the reserve rocker switch you are simply bypassing the fuel cut off signal and reestablish power back to the fuel pump.


George

This is exactly the way I believe it works George.

Since I installed the Dyna 2000 ignition, I no longer have the OEM ignition box connected to the harness. So I no longer have a reserve function, and the rocker switch is always in the bypass position...... I now use that switch as an anti-theft device - switch it to the non-bypass position and the bike won't go very far!
Just as an aside, disconnecting the OEM box also disables the sidestand switch cut-out, so the bike won't crack if in gear (clutch in or out), but it will keep running if the sidestand is extended while in gear. And the clutch switch activates a light on the digital dash when the lever is pulled (clutch dis-engaged). One day I will get around to re-wiring it to address these - one day!.......In the meantime I just ride and have learned to live with these little inconsistencies!

Cheers
Harvy

[Capn Ron]

My understanding is that the sputtering you get from the engine when you hit the reserve level is the ignition being cut out on two of the cylinders??

I like that you are seeing a small sensor (switch?) on the fuel level sender...  Is there a separate wire from that switch to the harness?  As in a signal wire for the resistance of the level sender for fuel gauge function and a separate circuit for the small switch?  If so, that would make perfect sense.

I agree that the reserve switch on the dash should have been labeled differently.  Maybe "Res" and "Main"??

I like the clock...keeps me in check on long touring days and through different time zones.  I would like more info though...oil temp sender and readout is next on my agenda...then Randy's oil cooler...then I can report the improvement.  A volt meter would also be handy to establish a baseline so you could spot charging/battery issues early on.

Cap'n Ron. . .

[Capn Ron]

I found a post on the web regarding the reserve not working on a guy's FJ.  The rocker switch contacts were so corroded that the reserve circuit was always treated as "open":



He did a nice job of cleaning up the contacts and his reserve feature is now functioning as designed:



Cap'n Ron. . .

[Pat Conlon]

My understanding is that the sputtering you get from the engine when you hit the reserve level is the ignition being cut out on two of the cylinders??

Negative Ron, It is just as George explains it above ^^^ it is a fuel pump interrupt.

I wonder where this 'ignition interrupt' idea keeps coming from?

We have been hearing it often....

[racerrad8]

Negative Ron, It is just as George explains it above ^^^ it is a fuel pump interrupt.

I wonder where this 'ignition interrupt' idea keeps coming from?

We have been hearing it often....

Because it interrupts the ignition circuit on both of my 86's as they do not have fuel pumps...


Thing that make you go hmmmm

Randy - RPM

[ribbert]

My understanding is that the sputtering you get from the engine when you hit the reserve level is the ignition being cut out on two of the cylinders??

It has been said categorically here (by someone else thank goodness) that this is a myth. I agree.

If the coils were cutting out there would be an immediate return to normal operation once the switch is flicked. There is not.

I believe it cuts the fuel pump out.

The behaviour of the motor, both when it indicates the need to go to reserve and when the switch is operated is entirely consistant with this. That is, it takes a few seconds to kick back in after it has been flicked. That lag is the time it takes for the bowls to refill.

A motor deprived of fuel or spark has entirely different characteristics and the function of the reserve switch is consistant with fuel starvation, not spark interruption.'

For those that need it proved, it would be a simple test.

Noel

[Pat Conlon]

Negative Ron, It is just as George explains it above ^^^ it is a fuel pump interrupt.

I wonder where this 'ignition interrupt' idea keeps coming from?

We have been hearing it often....

Because it interrupts the ignition circuit on both of my 86's as they do not have fuel pumps...

Of course, that explains it.....