Fuel problem!

I

Ice3460

Registered
Hey guys, I'm really hoping someone can help me. I seem to be chasing ghost and want to get this issue rectified. My 2000 Hayabusa ran fine last season. About a month ago she started acting funny. She would start up and idle fine..but when I reved her up she wouldn't push past 3000 rpms unless I pulled the throttle slowly but then still wouldn't redline. If I pulled quickly she would usually stall or stay at 3000 rpms.

I went and replaced a few things. I put new spark plugs in, took apart the external fuel pump and replaced the filters inside of it. I also replaced the petcock, As well as emptied out the tank and filled it with new gas. When I went to take the tank off, one of the fuel lines snapped and i replaced those as well. But when I was removing the tank I noticed the fuel pressure regulator didn't have a vacuum line connected. When I put everything back together (including the vacuum line) the bike wouldnt start or would start and then immediately turn off.. this went on for about 3 min.
At that point I thought to remove the vacuum line from the fuel pressure regulator on the pump again...she started up immediately and idled perfectly fine.... but now my original problem was still there and I'm back to square one. Do you think its the fuel pressure regulator or the mass air flow sensor that the vacuum line is hooked up to? Or is it something completely different. Please help!! I'm at a dead end and would like to ride my bike again. Thanks guys and sorry for the lengthy post.
 
Ice3460 said:
The same thing.
Click to expand...
I'll bet it's not turned fully on. I had similar symptoms, and the petcock wasn't all the way open so it restricted fuel flow which starved the pump at higher rpm. Make sure it's fully open. It can be open enough to spill fuel under a gravity flow, but still not allow enough for the pump to pull all it needs. You can grind a slot in the face of it so you can turn it with a screwdriver, that makes it easier.
 
I dont think its the petcock. It was running ok after i replaced that..then the symptoms started out of nowhere
 
Sorry..i should of stated that I replaced the petcock prior to the problem. Like about 2 weeks before..it was actually really gross and clogged. Same as my filters in my fuel pump
 
Petcock is fully opened and fuel lines aren't kinked. I checked them this afternoon. Could this be the mass air flow sensor or the fuel pressure regulator?
 
And the mass airflow sensor is directly connected to the fuel pressure regulator which is operating the regulator
 
Back in 2003 on my 2000 I had the same symptoms.Checked everything.Now what leads me to believe I have your fix is your report of all the "gross and clogged" things in your fuel system. I took the tiny little screens off the top of each injector and cleaned all the "gross" off them with a toothbrush.Re-install...walah...prob solved. Its an easy,no cost fix.Can't hurt to try.
Rubb.
 
another strange thing is that when the fuel preasure regulator was hooked up to the vacuum line to the mass air flow sensor... the bike wouldn't really start or run.. as soon as i unplugged the vacuum line, it started and idled fine
 
I'm not sure how the regulator is controlled, but what you're saying seems logical. In my experience with the early bikes the pump and lines have been the cause of many issues, not the regulator. Obviously not ruling it out, but check th common, easy, and cheap stuff first.
 
Ice3460 said:
another strange thing is that when the fuel preasure regulator was hooked up to the vacuum line to the mass air flow sensor... the bike wouldn't really start or run.. as soon as i unplugged the vacuum line, it started and idled fine
Click to expand...
Check the routing of all the vacuum lines,somebody may have fugged with it and messed it up.It's not correct,but if it runs fine the way it is,maybe leave it.Not correct I know,but meh,what the heck.
Rubb.
 
Thats the thing.. it only idles with the fuel pressure vacuum line disconnected...but then wont rev passed 3,000 rpms.. if I hook the vacuum line up it won't even start
 
Hi so i have a 2000 busa and i bought it from a friends wife to help pay for funeral services after he past...he had removed pair valve and did an airbox mod...i never started it cuz 2nd gear was gone...so after about a year i finally replaced trans i finally started the bike and it runs like crap...vacuum lines were all off the bike...i looked at pictures online but none of them shoe me a pair valve delete and air box mod...also i noticed the vacuum line supposed to hook up to fuel pressure regulator was sucking gas out of the regulator...im not a bike mechanic so idk if this is normal...please help!!! Pictures is a plus thanks in advance
 
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