Need some help here please.

[criomega]

OK, so here's the deal. My cold busa runs pretty good but once its warm and you shut it off to restart it it starts and stalls, starts and stalls even on choke/high idle. now if you keep turning off, back on the key and trying over and over again you can get it to run fine 1 time in 30 trys. As far as riding goes, it can be moving along just fine, you snap the gas and sometimes it rips but other times it falls on its face and some of those times it does it so bad you have to down shift to another rpm range for it to have power again.

This is whats been done to this stock bike with D&D slip ons, a PCIII and a smart TRE. The plugs replaced, the air filter replaced, the fuel pump and filter removed, checked cleared, The fuel pressure reg replaced with a modded one with a few more psi(Thanks to Daniel) The TB syched, the PCIII unplugged as well as the TRE and tested with and without one or the other or both and nothing has worked.

I'm to the point of taking this thing and parting it out being as I can't sell a bike that runs like crap...half the time. I wish I could walk out to it, put the key in, start it up and ride it without having to mess with it every time. I don't think its injectors or fuel pump because why would it run great sometimes and minutes later suck those are parts that should work good or bad not alittle of both. I think it may be a sensor or something but I cant go go out and buy 1 sensor at a time because that just dumb and I don't know of any shops that I feel are good enough to work on it and there's no way I'm taking it to a stealership after taking to a few different service department people and felling I know more about bikes then they ever will.

Does anyone have any ideas as I'm open to any?

 

[mike1180]

Most problems are fuel or spark (or sometimes both)
It sounds like fuel to me.
It would be nice to have it happening and then remove the PCIII from the equation (just unplug it and put it back to stock) just for troubleshooting.
See if that makes a difference in starting.
Intermittent problems are a bear, and you have to try something when it is happening to be able to isolate it for sure.
Keep checking back and we will try and help.
Sounds like a "not so typical problem."

 

[mike1180]

Hey anyone ever had a vapor lock on one of these?
Sure sounds something like that.
Only happens when hot.

 

[TXBusa05LE]

Most problems are fuel or spark (or sometimes both)
It sounds like fuel to me.
It would be nice to have it happening and then remove the PCIII from the equation (just unplug it and put it back to stock) just for troubleshooting.
See if that makes a difference in starting.
Intermittent problems are a bear, and you have to try something when it is happening to be able to isolate it for sure.
Keep checking back and we will try and help.
Sounds like a "not so typical problem."

+ 1 for fuel, start at the bottom & get the service manual.

 

[Wag]

Don't rule out the fuel injectors. You could have them cleaned. Might try some Sea Foam and see if that does the trick.

--Wag--

 

[criomega]

Well I've taken the PCIII off a few times so far (seems fat without it) I've run sea foam and other cleaners in it over the last few hundred miles and thats made zero change. I really don't think it would be injectors as if they where plugged they would always be plugged or gummed up. I'm really thinking its a sensor the way its off and on while riding but its always hard starting once warm/hot.

One other thing While I run it plugged into the my laptop with the PCIII I can see a readout of the rpms alot better than watching the tach. As I twist the gas even so slow it goes from like 3k -3200, stays there as I keep twisting and Boom revs to 6-7k like a 2 stroke with the reeds opening. total flat line between 4% throttle to say 9 % throttle (under no load) that would make me think the TPS sensor is bad but the laptop is seeing the throttle open %.

I'm losing my mind here!!!

 

[Danfaster]

When did you notice it starting to run bad? After you changed plugs? Does the bike seem to be lazy or down on power when the problem occurs? You can usually narrow the problem by what you have worked on recently.
With the air box removed, off to the side with the air intake sensor attached. Remove one injector plug at a time to see if the rpm changes, this will narrow down which cylinder is the probem, if in fact that is. If there is "NO"change on a cylinder, it will be suspect. This will probably put the FI light on, but an ignition cycle will clear the code.
Trouble shooting is done by eliminating areas and narrowing down the possibilities.
Good luck!! Sometimes you will get lucky and notice some connector not hooked up. Don't have tunnel vision! Look around!

 

[criomega]

Its been this way since the day I bought it. The things I have done seem to help alittle bit but nothing fixes it. I have gone and unplugged ever plug on the bike, checked to make sure there was no corrosion, no bent pins the works. I've always thought it was elcetrical by the way it comes and goes so I looked at the whole harness from front to back on the bike.

 

[Wag]

It just sounds so much like a fuel delivery or fuel mixture problem. Try replacing the IAT and see if that does the trick. It could be sending bad info to the ECU.

--Wag--

 

[Danfaster]

As an Automotive tech with GM we would do a dealer approved TAP test on the ECM or in this case the ECU. Simply have it running and slap the ECU with your open hand to see if the bike hiccups or runs any differently. Use some restraint, you don't need to take out your frustration on the bike....at least not yet. Wait until you get it running properly, then you can beat on it the right way!

 

[JINKSTER]

Jinkster to the rescue...try this for starters...

getcher self "wired"...

then jump the diagnostics plug...

then?..turn the ign. key to the on position and?...

read, record and translate any error codes that pop up on your lcd...

this will diagnose and "rule-in/rule-out' any possible sensor or fi issues.

L8R, Bill.

 

[criomega]

Jinkster to the rescue...try this for starters...

getcher self "wired"...

then jump the diagnostics plug...

then?..turn the ign. key to the on position and?...

read, record and translate any error codes that pop up on your lcd...

this will diagnose and "rule-in/rule-out' any possible sensor or fi issues.

L8R, Bill.

I will try this soon as I can get back to the bike. Thanks for the help and for the sych write up as it was yours that I used!

 

[JINKSTER]

I will try this soon as I can get back to the bike. Thanks for the help and for the sych write up as it was yours that I used!

cool...and to add?...(based on your "process of elimination" technics already attempted and failed)...?....by shear guessing...and only if there are a lot of miles on the bike?....i'm gonna say that the problem may not be electrically or fi based (and this will prove true once you run the diagnostics jumper and should discover "No Error Codes").....

that there is a slight possibility that this could be a mechanical problem...and judging by the "hard start-ups when warm/hot" report?...

IT MAY BE TIME TO CHECK YOUR VALVES CLEARANCES!

as?...

your electronics and fi systems are heat sheilded...so it stands to reason that "engine temp" would not typically play a role here...however...

metal does in fact grow with heat...and tight valve clearances cold might start-up just fine...but let'em grow with eng. heat?...and viola...

"Hard-Starting"

now...some may say "vapor lock"..and i like many others have experienced vapor lock...however...vapor lock isn't fully & truely always, all-the-time a heat related deal...it's a random "as long as the engine has built-up enough heat to boil-off the last charge of liquid fuel and create a ton of pressure at maximun squish where did the piston stop" deal...and the engine may not necessarily be fully warmed-up when it happens...it just takes enough heat to boil off the last charge of un-burned liquidous fuel...and then?...you'll just hear the starter relay click away...in which case i simply jostle the bike between my legs while in 1st gear with the clutch in then as i slam it forwrd for the final time i dump the clutch...and this jars the piston break-over point/vapor lock syndrome.

i'll keep and eye on this thread at least once a day for you in case there's anything of value that i may interject....cause i commend anyone who conquers the fear of trouble-shooting and working on your own ride.

Good Luck and L8R, Bill.

 

[criomega]

Well you where right C 00 no codes. You really think a bike that just rolled 11k needs the valves adjusted? Yes its hard to start but it always fires its just that it stalls or idles very low. On high idle it will idle at 1100-1200 rpms and at that point if you get on it and try to ride it then what happens is you take off, the bike bogs down and is very jerky so of course you twist the gas alittle more then BAM! rear tire up in smoke front wheel up in the air. but untill you stop and and shut it on and off again and again with the high idle on untill it starts and idles at 3k with the high idle the thing is jerky and almost unridable below 6k rpms (I only use the high idle as a gauge to more easily tell when its at that point that its running right)

So what do ya think Bill?

 

[JINKSTER]

Well you where right C 00 no codes. You really think a bike that just rolled 11k needs the valves adjusted? Yes its hard to start but it always fires its just that it stalls or idles very low. On high idle it will idle at 1100-1200 rpms and at that point if you get on it and try to ride it then what happens is you take off, the bike bogs down and is very jerky so of course you twist the gas alittle more then BAM! rear tire up in smoke front wheel up in the air. but untill you stop and and shut it on and off again and again with the high idle on untill it starts and idles at 3k with the high idle the thing is jerky and almost unridable below 6k rpms (I only use the high idle as a gauge to more easily tell when its at that point that its running right)

So what do ya think Bill?

Okay cool...bike only has 11K on it kinda rules out valve adjust and no codes...and bearing in mind that this is a demon that rears it's ugly head only after the bike is warm?...and the pc3 and tre have been ruled out by POE..so now here's what i'd do next...

1. Find a friend with a busa nearby who's willing to swing by and swap out ecu's with you for one good engine heating ride...if his bike starts hi-cupping and yours runs dandy?..ya gotcher culprit...as engine heat may be having an effect on the ecu...and Note:...ecu swap out should take maybe 10 minutes at most to preform...plug and play.

2. Double check all vacuum lines (especially the jumpers on your throttle bodies)...check for dried out and cracking lines and/or leaky connections.

3.? three is ugly...3 would be your wiring harness...where one or more wires may be carburizing with heat at an over-lapping connection hidden uder the wires own insulation...anywhere along it's length...which involves yanking the entire harness and mounting it to a sheet of plywood to inspect each and every wire over it's entire length by one guy wiggling the wire every inch or so while the other pays close attention to an ohm meter to run a continuity check...one-by-one...on each and every wire for it's entire length.

oh and..one other thing...i noticed you refer'ed to the bike as being on "High Idle" whilst only turning 1,100-1,200rpms...so...if you're meaning to say that while you have the fast idle/choke to it's full on position and the engines only turning 1,100-1,200rpms?...then THAT tells me that your problem is a very simple one...your idle adjust is grossly low as it should be turning those sort of rpms with NO fast idle/choke...and properly synched and tuned?...the bike should start just dandy with NO fast idle/choke..and if your idle is adjusted waaaay low like that and your TB butterflys are that closed at idle?...it could cause all the symptoms you've described thus far.

now...go out to your garage...start the bike...let it warm up and begin turning your idle adjust screw to bring the engine rpms up too hold a steady 1,250-1,275rpms with....NO fast idle/choke...then take your bike for a ride and see if she don't pin ya against the hump!

I'll be waiting to hear the results. L8R, Bill.

 

[Mr Bogus]

you need to get some "testing" done..

get a fuel pressure gauge on the thing... seems the basics are forgotten all too often..

If you are going to work on your own stuff there are tools you need to own.. a GOOD pressure gauge is mandatory along with a few other tools..

Here is pressure, voltage, amperage, temp all in one... I can not even guess how many hundreds of repair jobs I have diagnosed with this setup..

Fuel pressure is probably the #1 issue with most "ill running" vehicles..

 

[Mr Bogus]

hmm picture was there a minute ago..

 

[suzuki4life]

The fuel pressure reg replaced with a modded one with a few more psi

well I am betting that right there is your problem

no clue why you felt a basically stock bike required more fuel pressure. Bike in stock form now will feel fat. Get the bike mapped, its probably loading up at idle and low speeds.