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Level gauge vs. ignition

Started by Bob C, July 11, 2023, 08:55:12 AM

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Bob C

  From working on my 1992 I found that the fuel level is tied in with the ignition . There must be a reading on the fuel gauge to start the bike ,less than zero mark,or slow indicating fuel gauge will block the ignition . Also,side stand must be up ,etc .

Pat Conlon

How did you determine that the fuel level is tied into your ignition?
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

Sparky84

Quote from: Bob C on July 11, 2023, 08:55:12 AM
  From working on my 1992 I found that the fuel level is tied in with the ignition . There must be a reading on the fuel gauge to start the bike ,less than zero mark,or slow indicating fuel gauge will block the ignition . Also,side stand must be up ,etc .

Not on the 1100, my fuel gauge reads empty when there's still over 100 k left in the tank,

But you could also be right, mine started the other month and ran really crap then stopped, tried to start again and it would turn over but not start, put some fuel in and it started almost right away. So when you're out of fuel it won't start.
1984 FJ1100
1979 Kawasaki Z1300
1972 Honda CB750/4 K2

RPM - Robert

If this is true how is it possible to start and run any FJ on an auxiliary tank with no tank or fuel level gauge attached. The side stand also does not need to be up to start.
:greeting:

Bob C

  I studied the wiring diagrams for ,at least, the '92 FJ's , and the wiring shows a tie-in with the ignition and fuel pump . Maybe some earlier ones will start with just a test tank. Trying to get more on this just gets you to the " take it to your dealer for service " general statement

RPM - Robert

You are still looking in the wrong area and have a different problem than the fuel level gauge. What that is I don't know but it isn't your fuel pump or fuel level.

1) You can hook the auxiliary tank to the fuel pump with the tank completely off and run the bike. Hence my first response.

2) You can even completely disconnect the fuel pump and run a fuel pump bike on gravity feed to get you home in a pinch if your fuel pump craps out. (This would require a length of hose from the tank to the carburetor, thus bypassing the fuel pump.)

gdfj12

A 2-3" section of a basic BIC ball point pen tube fits nicely into the stock fuel hoses (I keep one in my tool kit, it's been used). Just remove the 2 hoses from the pump, connect them with the BIC pen tube, tighten clamps as usual, ride off. Note, a brass barbed coupling fitting to fit the hoses can also be purchased at a hardware store. Keep your speeds lower as the fuel flow will slightly lower and you can end up with fuel starvation issues at elevated highway speeds and spirited twisty road riding.

 
George D
'89 FJ1250 ~'90-black/blue
'87 FJ1250 ~streetfighter project
'89 FJ1200 ~white/silver, resto project
'88 Honda Hawk GT, resto project

Bob C

  Thanks for the inputs. I think there are different models of FJ , mine is an FJ1200D . I never found any info on its existence . The wiring diagram in my owner manual shows one wire from the level gauge float arm which goes to the level gauge. Then there is a second sensor which has a wire which goes to the relay assembly, fuel level warning light, and ignitor unit . I never really found any data on how these units work, just a few wires going in and that's that. I did read that the side stand switch, clutch lever switch, neutral switch ( and maybe fuel ? ) are all part of the circuitry involved . It says in the owner manual " this model is equpped with an ignition circuit cut off system". Anyway, I seemed to find if my level gauge reads more than "E" ,it will start. It says E indicates about 1.3 USG left and the rider should switch to "RES" ( reserve ).

racerrad8

The fuel system and connection to the ignition system was discussed without a clear resolve on how the system works. I believe this system alters the ignition cycle as a warming to switch to reserve, but others believe it shuts off the fuel pump. I have added the link of the discussion below which includes wiring diagrams.

https://fjowners.com/index.php?topic=16857.0

But, in all of our years of working on every model of FJ amd even the XJR that followed, your symptoms of no start have never been described.

Randy - RPM
Randy - RPM