FJ refuses to run Please help!

[bil2on]

My bike was fine one day then the next would not start.
I want to replace and repair everything anyway so have replaced many parts but still wont go.
So far....
new fuel lines and filter,
new coils,
new plug caps,
new spark plugs,
replace wiring loom with a better condition one,
cleaned out carbs with new jets and needles.
All new yamaha parts.

Put it all back together with fresh fuel but still does not run.
The starter and fuel pump are working fine.

Any advice please?? Relays??

[Motofun]

Ran "yesterday" doesn't run "today"...hmmmm
Fuel/compression and spark.....
1.  Verify spark is there by pulling a plug and holding it against the casing while giving it a crank.
2.  Verify fuel is actually making it to the carbs and a filter isn't plugged.
3.  I doubt compression is a problem, try squirting some ether into the crab throats while cranking and see if it fires.

[bil2on]

thanks. Tomorro I will check the spark. If there isnt one what can I do next?

[Urx]

A wiring diagram and racing back through the elements of spark creation
Does spark plug spark ok on known good coil
Test coil primary and secondary windings for correct resistances
Swap in a known good ecu
Check inductive pickup is not open circuit
That's pretty much everything in the ' make sparks happen' chain

[bil2on]

Thanks Urx. First time Iv delt with this so learning as I go

[Old Rider]

some more things to check is :
1 Try to spray a little starter fluid into airfilter if it does not fire there is no spark and it is a electrical issue . If it fires then dies there is a fuel problem.
2 check the clutch switch the wires sitting under the clutch reservoir. Jumpwire them if it starts it is a faulty switch
3 check the sidestand switch by jumpwire it ( i dont remember how i did this  right now ) i think it is the green electrical connection sitting on left side of the bike under sidecover
4 check the neutral switch
5 check that the blue and white wire in the wire loom  that connects into the big relay sitting left  side of bike under the front fairing has good connection .On my bike it was broken and after fixing it it started
5  check the fuses if the 15A is blown it will not start if i remember right.

[bil2on]

Got the bike going today thank you. The problem was a heavily corroded plug connection to the pulse generator.
Im still gonna check everything you just mentioned though.  Thanks for all your advice!

[Millietant]

Got the bike going today thank you. The problem was a heavily corroded plug connection to the pulse generator.
Im still gonna check everything you just mentioned though.  Thanks for all your advice!

Good to hear you've got it running