Using throttle during engine start

I can recall reading in posts about our anywhere machines that using the throttle during engine start does not do anything.

Well, I ran across some posts about cars that indicate it has a purpose. That purpose is to let the computer (ECU) know that the engine is flooded. To which the computer responds by supplying less fuel than it normally would during "crank mode". Reference

I have used the throttle to get mine to start and I'm fairly certain that I'd managed to flood it as the smell of gas was very strong.

At this point I'm wondering if anyone has the inside scoop - is this feature programed into the ECU on these bikes?

I don't have any "inside" info, but my understanding was that for pretty much all fuel injected motorbikes, you don't need to / shouldn't give it throttle to start it up. Just crank it over with the starter and the ECU will do the rest. So it's not like with carbs where you need to give it some gas to get it to start. I have been starting my wrr by just pressing the starter for over a year now with no issues.

if its different with cars don't know. I only ride bikes

Yeah, I've read many times that it has no purpose. And 99.999+ percent of the time, I agree that the throttle has not been needed.

The car feature I mentioned is on fuel injected cars and it is used to reduce fuel input. It seems that I wasn't clear enough about that point. Sorry about that.

I've only used the throttle a few times when I was fairly certain the bike was flooded. Cranked it over many times by just using the start button with no result and then I cranked the throttle and the bike started. Could have been a coincidence, hence my question.

The only start up problem I've found was cranking the motor over before the pump goes through it's cycle.

A couple of times I've needed to turn off the key, turn it back on, wait for the pump to stop, then crank the motor over.

Maybe this is why you felt the need (old habit) to work the throttle when starting?

I never need the throttle unless it's a warm start. Then i need quite a bit of throttle to keep it from dying immediately after firing up. It's rather annoying, but a dead battery is far more annoying.

Daamud wrote:

The only start up problem I've found was cranking the motor over before the pump goes through it's cycle.

A couple of times I've needed to turn off the key, turn it back on, wait for the pump to stop, then crank the motor over.

Maybe this is why you felt the need (old habit) to work the throttle when starting?

Are you implying that I'm old?!?! Joking aside, I learned to wait on the pump(s) before I got the WRR. The time that really sticks out I had just stalled the bike so it should have already been primed. Well, it turned into a marathon starting session. Not exactly what I needed with the temp being over 100. I'd been through the key/pump cycle routine at least three times before I finally tried the throttle. Perhaps the ECU has the feature. Perhaps just opening the butterfly helped.

chuckP wrote:

I never need the throttle unless it's a warm start. Then i need quite a bit of throttle to keep it from dying immediately after firing up. It's rather annoying, but a dead battery is far more annoying.

I have also had to coax the bike to keep it running a few times - after starting and otherwise. The last time it did that I ended up waiting 20+ minutes before the pump would even prime - bad fuel pump. I certainly want to blame the pump for it needing coaxing while it was running.

290... Presuming that you also have an aftermarket fuel tuner you might be able to tweak that problem away.

Heoz wrote:

I can recall reading in posts about our anywhere machines that using the throttle during engine start does not do anything.

Well, I ran across some posts about cars that indicate it has a purpose. That purpose is to let the computer (ECU) know that the engine is flooded. To which the computer responds by supplying less fuel than it normally would during "crank mode". Reference

I have used the throttle to get mine to start and I'm fairly certain that I'd managed to flood it as the smell of gas was very strong.

At this point I'm wondering if anyone has the inside scoop - is this feature programed into the ECU on these bikes?

It would/should be described in the starting procedure of the owners manual, and I do not recall reading that...but, if you could point that out...
Until then, I assume we do not have that feature.

Those of us who've been around for a while can remember motorcycles with carburetors and chokes that needed to be manipulated like an angry woman who's pms-ing to get our bikes running in a sweet spot on some days.

With the advent of sensors, ECU's, electronics and computer chips, and fuel injection, some people have never had the joy of trying to hyper-regulate the fuel-air mixture during cold starts.

I have a 2008 wr250x with the original battery in her. My start-up procedure has never varied regardless of temperature, humidity, or length of time bike has been sitting without running.

1) back out of garage
2) turn key
3) listen for fuel pump, and wait for it to complete cycle
4) stab starter button once - never holding it in for longer than an eye-blink
5) bike rarely starts on first stab - but fuel pump once again whirs into action for a tiny bit
6) stab starter button again and 99.9999999999% of the time bike fires right up


I never use the kill switch on bike to turn off - and I've never ever, not even once, used the throttle to try to "help" start the bike.

The fact that newer, fuel injected motorcycles come without any form of a manual choke tells me that a properly functioning system should never need to be manually coaxed into operation.

Heoz wrote:

I can recall reading in posts about our anywhere machines that using the throttle during engine start does not do anything.

Well, I ran across some posts about cars that indicate it has a purpose. That purpose is to let the computer (ECU) know that the engine is flooded. To which the computer responds by supplying less fuel than it normally would during "crank mode". Reference

I have used the throttle to get mine to start and I'm fairly certain that I'd managed to flood it as the smell of gas was very strong.

At this point I'm wondering if anyone has the inside scoop - is this feature programed into the ECU on these bikes?

It's true that fuel injected cars & trucks have what is called a "clear flood" mode programmed into the ECM. This requires the driver to push the accelerator to the floor & hold it there while cranking. The injectors are shut off when doing this & the car should start after a few seconds of cranking to purge the extra fuel from the cylinders. Don't know if the WR or other EFI bikes have this feature or not. A factory tech may know. As others have stated, the bike should start every time without having to crack the throttle open. If this has to be done frequently, there may be another issue involved. You may have a dirty fuel injector that is letting fuel seep past the pintle thus causing an overly rich mixture. Brand / quality of gas has an influence on how clean your fuel system stays. Avoid fuels that contain high percentages (more than 10%) of alcohol, it promotes corrosion in the fuel system. Don't know if automobile injector cleaners are recommended for bikes or not but I would consult a Yamaha technician for their recommendation. They may have a fuel additive to clean the fuel system.

mucker wrote:

Heoz wrote:

At this point I'm wondering if anyone has the inside scoop - is this feature programed into the ECU on these bikes?

It would/should be described in the starting procedure of the owners manual, and I do not recall reading that...but, if you could point that out...
Until then, I assume we do not have that feature.

That may be as close as we'll get to the inside scoop. Or perhaps one day I'll get my hands on an o'scope and check the fuel injector signal myself.

motokid wrote:

The fact that newer, fuel injected motorcycles come without any form of a manual choke tells me that a properly functioning system should never need to be manually coaxed into operation.

Do you mean old school choke that is a separate control? My fuel injected cars don't have those either. Keep in mind that I'm fairly certain that the bike was flooded. I suspect that you know what that smells like. Since you're going old school ... I recall seeing a flood fix procedure that included.. remove spark plug and put a match to it. Haha.. I do not miss carbs.

At least three other references here of people having to use the throttle to get them to start.

sswrx wrote:

...As others have stated, the bike should start every time without having to crack the throttle open. If this has to be done frequently, there may be another issue involved. You may have a dirty fuel injector that is letting fuel seep past the pintle thus causing an overly rich mixture. Brand / quality of gas has an influence on how clean your fuel system stays. Avoid fuels that contain high percentages (more than 10%) of alcohol, it promotes corrosion in the fuel system. Don't know if automobile injector cleaners are recommended for bikes or not but I would consult a Yamaha technician for their recommendation. They may have a fuel additive to clean the fuel system.

I'm happy to say that it has not been required frequently. I've only tried it a few times when the bike wouldn't start. It may have only actually helped, or appeared to have helped, once or twice. I'd like to blame the bad fuel pump here too but, it seems that would cause the opposite of flooding.

Your post got me thinking about the reason for the stall/flood in the first place and a bell went off. I did adjust the CO mode +3 or +5 from stock on my bike way back. Even though that doesn't seem like much when one considers the available range, I'm going to set it back to the setting it was at before I fiddled with it - zero. It may turn out that I never need to use the throttle again but if I do, I'll at least know that it wasn't on account of me adjusting the CO mode. If I do end up needing it again, I'll look back on your post and start from there.

Thanks!