Hard start after 8 weeks

[racer]

I left my 04 in the garage for eight weeks after my last trip. Went to start it up for a ride, and when it turned the key on, I heard a noise from either inside the tank or under it, that sounded like clunk. Hit the starter button and the motor turned over but it wouldn't start. Tried several times with no luck. Figured the battery might be low, so I put a charger on it. Still no luck. I opened the throttle a bit and got it to fire a little, it finally started and reved up, but died when I let off the throttle. Went through the same procedure again, and when it finally started with an open throttle, I let it rev a bit and then it would idle down. Took it on a trip, and no problems since.

Anyone have any theories?

 

[Don B]

No theories but mine has had exactly the same problem sitting for 2 weeks. Dealer looks at me like I am some kind of idiot. Fighting front end wobble since new too. Currently have 3500 miles and am thinking about selling.

 

[Fred H.]

Sounds to me like it was feeling neglected and wanted to let you know about it.

If it happens again, put a fuel pressue gage on it and see if the fuel pump is working and up to the proper pressure.

 

[radman]

"Yeah. You show up after 8 weeks, and expect everything to be just hunky dory. Well it doesn't work that way pal, I have needs too, ya know! Ya think you can just waltz in here, and old Feejie is just panting in anticipation, hot ta trot as soon as your sorry ass swings a leg over?! [SIZE=12pt]WELL IT DOESN'T WORK THAT WAY BUCKO!! I KNOW WHERE YOU'VE BEEN, AND WHAT YA BEEN DOIN'!! THERES ANOTHER, ISN'T THERE!! THERE ALWAYS IS!! I SHOULD HAVE LISTENED TO MAAMY YAMI, BUT NOOOOOOOO, I HAD TO GO OUT AND JUMP UNDER THE FIRST ****** THAT CAME ALONG!!!!!!!!!!!!!![/SIZE]

 

[okmac]

Thanks a lot Radman, you just about made me choke on the drink I was having., warn me next time.

mac

 

[jestal]

The clunk you hear from the tank is hydraulic noise of the fuel pump priming...sort of like a water hammer when the fast moving column of fuel from the pump hits the pressure regulator in the fuel rail and stops.

The pump only runs for a couple of seconds when the key is turned on unless the engine is running so there is just a brief interval of pump operation with the key on.

In your case, I suspect the fuel rail pressure had drained down over time and was unpressurized and/or there was some vapor in there. You turned on the key and the pump primed the system but that brief run time was not enough to completely purge/prime the entire rail from sitting for 8 weeks. You then cranked. The fuel pressure is still low in the rail so some of the injectors open with less than optimum pressure. Liquid fuel entered but was not the full charge and not enough to support combustion....so the fuel that did enter condensed on the cold spark plug tip and fouled them. This makes subsequent trys at starting even harder even though the fuel pressure was then up to snuff. A lower than normal battery may have also delayed the buildup of full operating fuel pressure as the system was trying to pump/purge/prime/pressureize the rail with very low system voltage due to cranking. Cranking can pull the battery down to 6 or 8 volts with a marginal charge which is where the fuel pump performance is starting to really fall off. Put some old fuel that has reduced volitility from sitting on top of the situation and viola....you get a hard start, stalls after start and rough running. After the engine gets some heat in it the plugs clean up fine, the old fuel gets run out on the trip, the battery gets fullly charged and presto...you are back to normal.

On relatively brief soaks the system will retain pressure in the rail so the brief interval of fuel pump run time before cranking will almost always be sufficient to fully prime/pressurize the system resulting in an instant start. Plus, "normal" starts have a fully charged battery, better fuel quality (the volitility of the fuel hasn't weathered), etc. so the situation seems to fix itself.

In the future, after long periods of disuse charge the battery, do 4 or 5 key on/key off moves before cranking to thoroughtly purge and prime the fuel rail before cranking and put some fresh fuel in the tank before starting. That would eliminate the situation you describe.

I would basically say that your experience was perfectly normal for any port fuel injected vehicle that sat for a long period of time without starting.

 

[wheatonFJR]

Thanks Jestal.

That really helps me understand some of what has gone on in the past. I have had an occasion or two where it hasn't started due to neglect or too much water where it shouldn't have gone (washing after a long trip).

Appreciate the insights...

@Don B, check wheel balancing if that hasn't already been checked. I can't imagine one would come out of the crate out-of-balance - but you never know. KEEP the bike - it's worth it! Best bike I've ever had...

 

[teerex51]

Jestal,

Thanks for a helluva write-up. :clapping:

I've saved it so I'm gonna use it on my Forum next time some guy posts a similar complaint. Just a matter of time, I guess.

Rad,

there must be an open carpet glue container in your garage, bro

Stef

 

[radman]

Jestal,
Thanks for a helluva write-up. :clapping:

I've saved it so I'm gonna use it on my Forum next time some guy posts a similar complaint. Just a matter of time, I guess.

It's all been said before, ad nauseum, but as usual, until jestal writes it out, it isn't taken seriously. This is not, nor should it in any way be construed as a slam on jestal-he's smart, has good advise, and is a valuable contributor to this forum. It's just that, too often, good advise comes from other contributors here, but is ignored,or at the least, discounted, because of the author, though there is a lot to be said for the format jestal uses.

Rad,
there must be an open carpet glue container in your garage, bro

Stef

Ya think? Leave in the am for Reno, just getting a few things together, so I'm a little pumped in anticipation. You can expect more of the same as the day progresses......

.

 

[MikeYork5]

Good advice - had the same problem with mine last month, after it sat for a few weeks. Tried starting and was unsuccessful (I could smell raw fuel though). Had a hell of time getting it going - after several attempts, and letting it set and charging up the battery finally got it to take. Like your advice on cycling the key a few times after a prolonged rest, makes sense.

 

[racer]

Thanks Jestal. I appreciate the explaination although it was not as helpful as the advice given by Radman in big red letters. I suggest Radman try Jo Mama at ADVrider. They'll eat him alive there. :yahoo:

 

[Don B]

WOW!

Jestal, where do you live man! I want you to work on my bike.

 

[Fred H.]

I am not sure how, or if, this problem is affected, but the fuel pressure regulator is now inside the gas tank on the 06 models, and so there is no return line from the fuel rail. I assume the rail remains full of gas when the bike is shut off, (unless an injector is leaking) so it seems like it should re-pressurize easily.

It is also worthwhile to note that the fuel pressure on the 06 has been significantly increased, which brings up another interesting point. Most folks that are doing the Barbarian mod are increasing the mixture setting by 7 increments, based on the testing on previous model years on a dyno. I can't help but wonder if this data is still good for the 06, since now the fuel pressure, and presumable the mapping as well, has changed.

Food for thought. I guess someone needs to put an 06 on a dyno and play with the mixtures. A four gas, gas analyzer readout would also probably do the trick.

 

[radman]

The mapping may indeed have changed, but the increase in pressure will have no effect on the amount of fuel delivered-this is determined by the engine and the desired characteristics,which haven't changed. It appears the same issues that existed in earlier models exist still, so I doubt much has changed. The FI still tends to be on the lean side, fine for an automatic equipped auto with a lower power to weight ratio, but not so great on a much lighter platform like the bike. Richening up the mix still has the same effect as it did on earlier models, but remember that the original Barb mod stressed using a gas analyzer at each exhaust port via holes drilled into the header for an accurate adjustment. Anything else is guesswork.

 

[cota95]

I had the same problem with my 04 when the battery was getting ready to give up the ghost (last March). The battery on these babies don't last very long...

 

[SkooterG]

I had the same problem with my 04 when the battery was getting ready to give up the ghost (last March). The battery on these babies don't last very long...

Hmmm........ Two years, 11 months, and one day on my stock battery in my 04. (So far) Not to mention 80,000 miles, and being in the extreme heat most of the year in Arizona. I would say that is excellent service life and has exceeded my expectations.

 

[wheatonFJR]

It's all been said before, ad nauseum, but as usual, until jestal writes it out, it isn't taken seriously. This is not, nor should it in any way be construed as a slam on jestal-he's smart, has good advise, and is a valuable contributor to this forum. It's just that, too often, good advise comes from other contributors here, but is ignored,or at the least, discounted, because of the author, though there is a lot to be said for the format jestal uses.

Radman, I disagree with the above statement in this case. I know there have been many discussions of "Bike can't start"...

However, jestal's write up was the first time in all those discussions that I felt like I could follow along and comprehend what was being stated. It also was comprehensive in nature and seemed to explain to me all what could be happening under various symptoms. I know you are far more technically inclined than I am, so maybe his writeup was boring or old news to you...however it was quite insightful to me so don't diss his words...

I don't know jestal at all but judged the words on the clarity of the words themselves, not who was writing them...

Therefore, ad nauseum or not, that was one damn good write up and should not be dismissed because you have felt some of your helpful technical advice were ignored in some other time or place...

 

[Fred H.]

The mapping may indeed have changed, but the increase in pressure will have no effect on the amount of fuel delivered-this is determined by the engine and the desired characteristics,which haven't changed.

I would respectfully disagree with this. Fuel delivery is a factor of the pulse width of the signal sent to the injectors (which determines the timing and duration the injector is open) AND the pressure of the fuel rail. If you increase fuel pressure, you spray more fuel for a given pulse duration (increase in nozzle velocity, and flow rate).

An old tuners trick frequently used to richen the mixture in a fuel injected engine is to add an adjustable fuel pressure regulator so you can turn up the pressure to richen the mixture.

Additionally, many FI engines use a rising rate regulator that has a vacuum line connected to it so that it can increase the pressure during high demand times as the vacuum level approaches atmospheric. Some of the really slick aftermarket regulators let you adjust rate of gain as well as onset of gain and some of these can increase fuel flow up to around 35%-40%, but I digress.

I assume that since Yamaha increased the fuel pressure on the rail, that they also had to rewrite the map for the ECU.

Sorry for the thread hijack.

 

[jestal]

The mapping may indeed have changed, but the increase in pressure will have no effect on the amount of fuel delivered-this is determined by the engine and the desired characteristics,which haven't changed.

I would respectfully disagree with this. Fuel delivery is a factor of the pulse width of the signal sent to the injectors (which determines the timing and duration the injector is open) AND the pressure of the fuel rail. If you increase fuel pressure, you spray more fuel for a given pulse duration (increase in nozzle velocity, and flow rate).

An old tuners trick frequently used to richen the mixture in a fuel injected engine is to add an adjustable fuel pressure regulator so you can turn up the pressure to richen the mixture.

Additionally, many FI engines use a rising rate regulator that has a vacuum line connected to it so that it can increase the pressure during high demand times as the vacuum level approaches atmospheric. Some of the really slick aftermarket regulators let you adjust rate of gain as well as onset of gain and some of these can increase fuel flow up to around 35%-40%, but I digress.

I assume that since Yamaha increased the fuel pressure on the rail, that they also had to rewrite the map for the ECU.

Sorry for the thread hijack.

I think both of you are right...in a way.....

If the fuel pressure increases then the pulse width simply need to be reduced to deliver the "same amount of fuel". The fundamental fuel map in terms of volumetric efficiency and RPM that models the engine air flow capability is indeed the same as long as the air flow characteristics of the engine stay the same (regardless of fuel pressure.) That map just specifies how much fuel the engine needs at any particular operating condition. Changing the compression, cam timing, intake or exhaust ports, exhaust pipe, etc. would change the basic fuel map in a speed density system but changing the fuel pressure does not.

Soo....Yamaha did not have to re-write the basic fuel map just because the fuel pressure changed.

The fuel pressure , that is taken into account in the basic injector delivery rate curve, is covered in the part of the speed density fuel calculation that calculates the actual pulse width needed to deliver the amount of fuel calculated. That is not part of the fuel map that needs calibrating...it is simply a hardware correlation the ECM needs to accomodate the injector sizing and (and fuel pressure) of the system.

Soo...Yamaha would have to adjust the injector constant value in the speed density calculation in the ECM to account for the different flow rates of the injectors caused by different fuel pressure.

An aftermarket adjustable fuel pressure regulator is just a crutch to allow changing the actual fuel delivered for tuning purposes. Any OEM calibration would provide the correct map and injector constants for the speed density calculation to work correctly.

There are port fuel injection systems on the market that do not have pressure regulators. Using a fuel pressure sensor the pulse width is varied to account for the changing "injector constant" . Similarily, there are systems in widespread production that have fixed fuel pressure that does not reference manifold pressure. These systems measure and monitor manifold pressure (vacuum) and have offsetting injector pulse width modifiers to account for the constantly varying delta pressure across the fuel injector. These systems all still operate the same basic way with a fuel map that provides the system with the correct fuel required for the operating parameters of the engine....there are just a wide variety of injector constant modifiers used for the different systems to account for the different means of controlling fuel pressure.

Actually, fuel pressure regulators that change fuel pressure to change the injector flow rate at high demand points are pretty common. Most every supercharged or turbocharged engine with port fuel injection has a boost referenced fuel pressure regulator that bumps fuel pressure accordingly as the boost increases....similarily the fuel pressure regulator decreases fuel pressure as vacuum in the intake increases. The whole point is to keep the pressure drop across the injector the same so that a linear injector flow rate or injector constant is possible. If not, then the injector constant must be varied according to the fuel pressure (or intake manifold absolute pressure) changing.