99 Busa Prob: Fuel or Electrical?

spdjunkey

Registered
First, this site and the knowledge passed by it's members is unbelievable. I've been a member since I bought my Busa. I don't have many post but I'm always on here reading and learning. With that said, I've searched every possible combination of words for solutions to my problem. Hell, just today I went through the last 1500 threads started in this section. I've found plenty of topics similar to my issues but none that seem to completely fit. Despite finding so many, most threads die off without a solution. Ok, now that I'm done whining, here's what I got.

I have a 99 with 7100 miles that I bought from the original owner in Dec of 08 with 3400 miles on it. It has a Yosh full tri-oval dual tip exhaust, BMC air filter and PCIII. I have not had it custom tuned yet. I know a generic map is no where close to what I need, but I don't think it is the root cause of my problem. I'm just trying to get the bike running the best I can before I shell out the money for the tune.

I have been dealing with rough idle, low mpg, running rich, hesitation, extreme on/off throttle, hard starting when warm and charging issues (maybe). Since all this started I have taken the fuel pump apart and removed all screens, to include the ones on the injectors, and the filter. I put an external filter in between the pump and fuel rail. I've synced the throttle bodies and adjusted the TPS, both numerous times to make sure they stay correct. I've changed plugs and run multiple cans of injector cleaner through it. I've adjusted the throttle cables. I have tried every map that Dynojet has that would load into the PCIII. Some are better than others as far as the hesitation and richness but the idle roughness is always there. I know there are other things that I should do, like getting the injectors professionally cleaned. I just wanted to get some input before I aimlessly go spending more money.

All of my problems sound like they are fuel related. But I have recently noticed that the dash lights and headlight flicker at idle. If I put the fast idle at say 2500 RPMs they just flicker faster and the RPMs fluctuate by about 500. If I don't use my battery tender regularly, the battery won't have enough juice to start the engine. The battery is two and a half years old, so most likely needs replacing. But this morning I checked the battery and the rectifier as described in the manual. They both checked within tolerance. I didn't get any further because I broke one of the leads on my multimeter.

After all this, I'm just looking for opinions on whether one issue is causing the other or do I have multiple problems. Any insight or guidance is greatly appreciated. Sorry, for writing so much. And even more sorry if none of it makes sense. I'm just at the end of my rope with this. I just want it to run the way it should. Thanks for reading now please help me fix it.
 
But I have recently noticed that the dash lights and headlight flicker at idle. If I put the fast idle at say 2500 RPMs they just flicker faster and the RPMs fluctuate by about 500. If I don't use my battery tender regularly, the battery won't have enough juice to start the engine. The battery is two and a half years old, so most likely needs replacing.


EVEN IF IT CHECKED WITHIN TOLERANCE, take your battery to your local auto store and have it load-tested. A dead/dying battery can cause all kinds of weird gremlins......after reading above, looks like you're getting enough clues already. Best of luck.
 
I would start with the basics, make sure you are running a clean air filter, check your vacuum lines for leaks, make sure the vacuum line is hooked to the sensor on left rear of the airbox. I'm sure you've already unplugged the pc and ran it? How do the plugs look? All the same or is one look worse than the rest?
 
I would start with the basics, make sure you are running a clean air filter, check your vacuum lines for leaks, make sure the vacuum line is hooked to the sensor on left rear of the airbox. I'm sure you've already unplugged the pc and ran it? How do the plugs look? All the same or is one look worse than the rest?

Air cleaner is good. Checked and rechecked vacuum lines, especially the one on that sensor. PC has been disconnected but made no difference. I replaced the plugs three weeks ago when I pulled and cleaned the pump and injectors to do the in-line fuel filter. #2 was black and shiny. Pulled the new ones yesterday and they all looked the same, slightly darker than I think they should have been for new plugs. But i had to go through an MSF course this week and she was running super rich so I sort of expected it. So I cleaned them with Carb cleaner, checked the gap and re-installed. Ran a little better at speed, but still idles like a V-twin.

Something weird I forgot about, yesterday I was checking the rectifier and forgot to plug it back in before I started the bike again. It idled slightly better. And the lights didn't flicker at all. Any ideas why?
 
Check for for charging voltage.If its not charging or undercharging it wont run right.I had that issue last year.My HIDs would shut off so I thought it was a bad ballast, so I was sent a new ballast and bulbs, still did it.I checked my charging system and it was running 18volts at idle.Bike ran good, but my HIDs would shut off because the ballasts have protection built it so they dont burn up.So if yours isnt charging or its undercharging, that will make it run poorly.Also the basic MAP that the PC3 has to download that comes close for the yosh and bmc, probably still isnt worth a crap.Its better to have it dyno tuned.I gained power, fuel milage and better ridability after mine was done.
 
Well, checked the battery charging voltages again. Idle voltage is 14.6V. When I increase to 5k it drops to 14.05V. Is this right? Also, not sure how I missed this before, but the TPS resistance is off. Closed reads 1.1k instead of 1.3k and WOT reads 3.75 instead of 4.5k. Looks like a need a new TPS. Where is the best place to get one?
 
Can't help you on the TPS other than the dealer. Did you adjust it?

I was thinking about your flickering lights. I am applying automotive experience here, so take this with a grain of salt. Normally that could be caused by either a bad loop in the stator or a bad diode in the rectifier. Basically you are missing a phase of the "unrectified" voltage. This can be hard to pick up with a voltmeter, you will likely have a reduced output, but it is much easier to see on a scope with a waveform. Unplugging the rectifier would isolate both of these and leave you just running on the battery, which is nice clean power. I am wondering if one of these things is defective, and the "dirty" power you are getting as a result could be messing up the computer just enough to cause your issue?? Maybe someone who knows more than me on the subject can either confirm or tell me I'm full of it :dunno:
 
Highliner, what you're says makes sense. I noticed the idle cleaned up a bit and the flicker was gone with the rectifier unplugged. I just don't want to go buying random parts based on my perception. I'm not expecting it to run perfect without a true custom tune but it should be better than this. BTW, I did adjust the TPS. Numerous times actually. The lower resistance changed some but upper stayed the same. Thanks for the input.
 
You talking about the coils? If so, I tested the resistance and they all checked the same and within mfg specs. Anyone have any thoughts on my measurements of the TPS I listed above. Also, anyone ever take it off and check/clean the contacts?
 
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