fuel reserve switch

[Mattman]

The bike only runs in reserve when I switch to run it will begin to run out of fuel. I have continuity between the two wire leads in reserve but infinity in run. I took the switch apart and cleaned it and still no continuity in the run position. What am I missing here?

[FJmonkey]

That makes sense, the switch only needs to change from one state (open) to (closed). My '89 has the opposite problem. The low fuel light never comes on so I can run dry with the switch in ON position. But I don't think the issue is with the switch for either of us. As a clue, the switch only has 2 wires, it is acting like a single pole switch, on or off.

[Mattman]

Hmmm ok  maybe there's a relay, or some kind of electrical component in the middle of it all. Have to look at a wiring diagram and do some electrical mind squeezing work ugh

[ribbert]

The bike only runs in reserve when I switch to run it will begin to run out of fuel. I have continuity between the two wire leads in reserve but infinity in run. I took the switch apart and cleaned it and still no continuity in the run position. What am I missing here?

With the switch in the run position, the message to shut off the fuel pump comes from the sender unit in the tank when the fuel gets low, the reserve function overides that. From you description, it sounds like it is the sender unit. If I was trouble shooting this the next thing I would check would be the operation of the tank unit (in situ) and if that checks out, the associated wiring.

Start with the most likely and easily checked items, like has it got enough fuel to actually be on the main tank? and work your way from there.

IMO

Noel

[Mattman]

Yes full tank, Ill check the sending unit  thanks Noel

[Harvy]

Yes full tank, Ill check the sending unit  thanks Noel

Mattman, does your bike still have the OEM ignition module?


Harvy

[ct7088]

I'm looking at a 1200B wiring diagram. The red/white wire should have power and the red green should take power to the fuel pump relay, relay assembly, pressure sensor and the ignitor unit when reserve mode is selected overriding the low fuel light. Unplugging the tank sender should let the fuel pump run if the fuel sender is the problem. Is the low fuel light on?

Take all this with a grain of salt I have a 85 which doesn't have a fuel pump and I can't verify what I think is happening on this electric fuel pump bike.

Chris

[Mattman]

Hi Harvey,
I dont know if it has the OEM ignition module. I just got the bike put 35 miles on it and realized the carbs are off tune. and now going through everything especially the carbs, Has a Vance and Hines pipe, rotor, carb. springs needles jets ect. I just ordered from Robert at RPM a whole bunch of Yamaha carb jets springs ect. by recommendation of Robert  to get back to settings I can work with. Now I wonder if the OEM ignition module has been changed. I assume its behind the fairing somewhere. Ill look for it and see if I can tell.

Yes full tank, Ill check the sending unit  thanks Noel

Mattman, does your bike still have the OEM ignition module?


Harvy

[Mattman]

low fuel light is not on. I ride around in reserve with a full tank of fuel and then i switch it to run and it stars running out of gas. I switch it to reserve and runs fine again. No low fuel light. After I get my parts from Robert at RPM and I get the carbs and valve cover back together I will try that check by unplugging the sending unit and see what it does. Thank you for your Ideas this is really cool to have so much help from so many!

I'm looking at a 1200B wiring diagram. The red/white wire should have power and the red green should take power to the fuel pump relay, relay assembly, pressure sensor and the ignitor unit when reserve mode is selected overriding the low fuel light. Unplugging the tank sender should let the fuel pump run if the fuel sender is the problem. Is the low fuel light on?

Take all this with a grain of salt I have a 85 which doesn't have a fuel pump and I can't verify what I think is happening on this electric fuel pump bike.

Chris

[ribbert]

If the bike is new to you and you've only ridden it 35 miles, which way is switch rocked for reserve, forward or back?

Noel

[Mattman]

Up is reserve down is run just like it spells out on the switch plate lol by the way I've had 3 FJ S in the last 20 years lol

[ribbert]

Up is reserve down is run just like it spells out on the switch plate lol by the way I've had 3 FJ S in the last 20 years lol

Haha, that's fine, just checking. The basics are the most overlooked possibility when chasing a problem, everyone wants to jump in at the deep end.

Noel

[Mattman]

Thats true usually its something simple

[ct7088]

I'm looking at a 1200B wiring diagram. The red/white wire should have power and the red green should take power to the fuel pump relay, relay assembly, pressure sensor and the ignitor unit when reserve mode is selected overriding the low fuel light. Unplugging the tank sender should let the fuel pump run if the fuel sender is the problem. Is the low fuel light on?

Take all this with a grain of salt I have a 85 which doesn't have a fuel pump and I can't verify what I think is happening on this electric fuel pump bike.

Chris

No the red/green wire only goes to the fuel pump relay. The red/black wire always carries power to the other accessories. Check for power at the red/black wire at the fuel pump relay.
Gray wire is coil trigger
Green/red is from low fuel sender
Blue/black is power to the fuel pump
Black is ground
I'm blaming old age.

Chris

[Harvy]

Hi Harvey,
I dont know if it has the OEM ignition module. I just got the bike put 35 miles on it and realized the carbs are off tune. and now going through everything especially the carbs, Has a Vance and Hines pipe, rotor, carb. springs needles jets ect. I just ordered from Robert at RPM a whole bunch of Yamaha carb jets springs ect. by recommendation of Robert  to get back to settings I can work with. Now I wonder if the OEM ignition module has been changed. I assume its behind the fairing somewhere. Ill look for it and see if I can tell.

Yes full tank, Ill check the sending unit  thanks Noel

I asked about the ignition module because with my '91 I am using a Dyna 2000 system which eliminates the OEM module. The way  mine is wired I have the same symptoms as you are describing..... it will only pump fuel with the fuel reserve switch in the RES position.

I have never bothered to track down the reason for this.

Cheers
Harvy

Mattman, does your bike still have the OEM ignition module?


Harvy