Fuel Pressure Drops When The Fan Kicks

kamikazi89

Registered
Hello from Cyprus i just finished my homemade stage 1 on my gen 1 2006 busa.i set the idle fuel pressure an i check the bike on the streets for possible problems and all went fine until the time the fan kicks the fuel pressure drops about 6-8psi from the 42-43 set pressure and this happen and before the turbo install when the fan was kicks in the headlight dimmed a little.sorry for my bad english.any advise?
 
you either need a stronger batt or your fan may be starting to have issues. The older a fan gets the more amps it draws. I would bet on the battery first as this is your cheapest fix. Get the highest cca batt you can get.
 
Yea my battery is getting old.Any advise for stronger battery that suits the stock location?if that solve my problem im ready for the dyno
 
Battery changed and still the same happens also i check with multimeter the voltage and the generator dont charge the battery until approx 1200 rpm from there and up is okay and when fan kicks or brake voltage effected
 
1200 is right around/just above gen1 idle.
So it should be charging there, as you say it is.
But I don't think it will charge, or fully charge anywhere below that.
Not sure, maybe someone can clarify.
 
Try just unplugging fan to see if it is the fan motor that is pulling the extra power, or if it is in the wiring.
The fuel pump run well before the fan kicks but when the fan kick in the fuel pressure now with the new battery lower about 4 psi,with the old battery lowers 8psi and my worry is for the air fuel ratio when the fan comes on maybe will lean
 
1200 is right around/just above gen1 idle.
So it should be charging there, as you say it is.
But I don't think it will charge, or fully charge anywhere below that.
Not sure, maybe someone can clarify.
My idle is about 1050 rpm and maybe this is the reason for not charging
 
Have you tested the stator or rectifier?
David Offer has alot of good info in several of his threads. He chased alot of gremlins in his gen1.
 
1200 is right around/just above gen1 idle.
So it should be charging there, as you say it is.
But I don't think it will charge, or fully charge anywhere below that.
Not sure, maybe someone can clarify.

I think Sixpack is correct anything below 1200-1500 rpm the stator is only putting out about 12 volts. You have to run the rpms higher that that to get the 13.5- 14.2 volts that actually charge the bike.
 
I think Sixpack is correct anything below 1200-1500 rpm the stator is only putting out about 12 volts. You have to run the rpms higher that that to get the 13.5- 14.2 volts that actually charge the bike.

I thought you had said they still charged around idle, I couldn't remember exactly how low.
Thanks
 
I thought you had said they still charged around idle, I couldn't remember exactly how low.
Thanks

Wow dude you remember my post better than I do. It made me go out to the garage and check. Idle is 14.5 volts at the battery. Over 1500 rpm it jumps to 15.2 volts. Sorry for any confusion and thank you Sixpack for making me go double check myself.
 
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