Need Help SOLVED: 05 starts on 1 cylinder only under full throttle - fuel issue?

[faded_clearcoat]

SOLVED: vacuum line at the front of the airbox


Hi guys, new to the forum! Bought an '08 for myself in January and have been loving the thing, so I convinced a friend to get an 05 we found for a decent enough deal.

Unfortunately...while riding it home, the bike died at a light and we've not been able to get it to run for longer than about 5 seconds or so, and right now we believe it may be a fuel delivery issue of some sort.

We replaced the fuel pump so far, but the issue remains. It will crank and sputter for a few seconds on its own, then die. Turning over the bike under WOT will get it to fire on one cylinder (cylinder 1?), then allowing it to drop revs and SLOWLY opening the throttle seems to free things up, and it'll fire on all 4, but dies as soon as the throttle is closed. Any thoughts? I'm having him check out the plugs and coils right now, but would love to hear any advice you guys might have to offer while we troubleshoot this thing. She wants to run! I've read bogs of other posts, but haven't found anything that seems to describe what we're seeing, so I thought i'd make my own and hopefully document a solution here.

Thanks! I'll be posting a video of what's going on when i'm home from work this afternoon.

 

[Motogiro]

Welcome to our great forum!
Fuel injectors could have been clogged with particulate. Is the fuel new? Make sure your fuel pimp is provides 36 PSI fuel pressure. Did you get the OEM fuel pump?
Any error codes?

 

[faded_clearcoat]

Welcome to our great forum!
Fuel injectors could have been clogged with particulate. Is the fuel new? Make sure your fuel pimp is provides 36 PSI fuel pressure. Did you get the OEM fuel pump?
Any error codes?

Happy to be here! Seems to be a wealth of knowledge around!

(off topic, but it sure was hot in san diego this past weekend)


Anyways, plenty of old codes, we only just recently learned how to clear them out, but no active ones if I'm understanding things correctly - here's what i wrote down last night that was stored on the ecm:

19
21
22
30
33
34
46

I used diag mode to verify the tps is giving a good output, and the lean sensor reads .6 while the bike is upright (the bike was dropped by the po) which accounts for 19 and 30, correct?

Does the module account for historic codes versus active ones? I remember coming to the conclusion that none of these codes were active, but can't remember the d-number that I checked last night. Could have been the wrong one.

Our pump isn't OEM, but supplies good pressure when tested with a gauge. Fuel is good, we used fresh gas we bought a couple days ago, and while cranking the motor, we see the injectors spraying into each cylinder. Any way to test them without pulling them and taking them to a shop? Thanks!

 

[Motogiro]

One of the things with the pump may be volume at pressure. I've heard of fuel pressure looking good but when the throttle is opened and duty cycle of injectors increase there is a lack of delivery of needed volume. This would be evident by seeing the required pressure but a drop when the engine has started.

Yeah, it was pretty warm in SD!

 

[faded_clearcoat]

One of the things with the pump may be volume at pressure. I've heard of fuel pressure looking good but when the throttle is opened and duty cycle of injectors increase there is a lack of delivery of needed volume. This would be evident by seeing the required pressure but a drop when the engine has started.

Yeah, it was pretty warm in SD!

I'll keep that in mind!

I'll be over there to check on things either today or tomorrow, so i'll have another update around then.

 

[faded_clearcoat]

Hey guys! Got her back up! The vacuum line at the FRONT of the air box had come undone, and we hadn't noticed it was out.

That, a new set of spark plugs, and a fuel pump are all that were replaced. I suspect the culprit this whole time was that vacuum line, though.


Hope this helps someone out, and thanks for the help!

 

[Motogiro]

That's awesome! Yeah a big vacuum leak will cause a lean out. LOL!

 

[faded_clearcoat]

That's awesome! Yeah a big vacuum leak will cause a lean out. LOL!

Yeah, you should have seen the look on my face when I found it! My buddy is stoked to finally be able to ride too. Can't think of a lot of first bikes that are better than these!