Iaps sensor: dies at idle when connect hose

[mr1roll]

I have an 04 busa that sat for over 2 years. Ran fine before. De-rusted the system, tank, etc. But now when I hook the center throttle body vac tube to the isps sensor the bike died at idle. I ran it without the iaps vacuum connected to the sensor and ran crappy, plugs all heavy black now. I reviewed the vac lines and connections and looks all normal.

My question then is what causes the bike to die at idle when the isps vac line is connected to the iaps sensor?

[mr1roll]

Sorry, "isps" should iaps, intake air pressure sensor screwed to back of airbox

[sixpack577]

No codes?

[Hayabusa Wannabe]

I have an 04 busa that sat for over 2 years. Ran fine before. De-rusted the system, tank, etc.

Hi @mr1roll. How about cleaning the fuel injectors? I wonder if they are leaking or cannot supply enough fuel when the system is closed loop. I am just guessing on the specific causes but based on gunk in the tank cleaning them is practically required, and would align with the one known problem from the bike sitting.

[mr1roll]

Thanks, I did replace injectors as the old ones were quite dirty and was worth it. poop carb cleaner thru them before install...

[mr1roll]

Oh and no codes with or without iaps hose connected. Unconnected it just won't start. It will drive around this way but not running well

[mr1roll]

No codes?

No codes... Just no start with iaps hose connected

[Hayabusa Wannabe]

Thanks, I did replace injectors as the old ones were quite dirty and was worth it. poop carb cleaner thru them before install...

New/used OEM or other injectors?

[mr1roll]

I have the original which were in the bike when it ran great. I also have new injectors, not Amazon but not Dynatek etc.

As a quality engineer, and seeing I can recreate the problem of no start by connecting the vac line to iaps sensor, it almost has to be a lack of vacuum; maybe from corroded throttle bodies where the vac is created? I will pull vac lines to check for any cracks next but any crack would have just spontaneously occurred as the bike sat for a couple years so not very likely.

So after vac line check I'll pull throttle bodies to clean them as that effort will at least move forward with elimination of 2 strong issues.

***Also, I used open ai and asked my question of this situation and open ai also said it should be lack of vacuum which has a short list of potential causes.

So it appears that open ai can be a great too for troubleshooting as well!!!

[gsxlover97]

Did you ever find an answer to this issue? Mine is having same problem. Just replaced fuel pump and injectors and it will idle just fine. Plug that hose on it dies. Also if I give throttle it dies.

[Hayabusa Wannabe]

Welcome to the forum @gsxlover97.

[mr1roll]

Did you ever find an answer to this issue? Mine is having same problem. Just replaced fuel pump and injectors and it will idle just fine. Plug that hose on it dies. Also if I give throttle it di

[mr1roll]

No luck. New fuel pump, battery, 2 sets of fuel injectors but all of them have verified to work, 3 sets spark plugs, verified no leak in the vac lines involved, fuel tank has tank liner now after de-rusting it, verified the 2 tank hoses (back of tank) are open to allow air flow. Same as you said, idles but twist the gas a bit and it cuts out. Hook hose to sensor it does.

I did get another iaps sensor from a buddy but no change. Maybe it needs a new sensor but I am getting done trying anything more and may just sell it as is, really

Maybe it is not worth paying a shop to fix mine with 42k miles on it.

If you want to email more about this topic or chat or call I'm all for it just let me know but I don't know at this point what else I can come up with for possiblities.
Matt

[03busamd]

Did you ever find a solution? Same issue and nobody can answer this

[mr1roll]

Nope. Trying 2nd set replacement injectors tonight and will post but I am not hopeful. Ran great as it was, replaced, cleaned whole fuel system including pump. These injectors are a last hope before sell as is.

[Hayabusa Wannabe]

This may be far fetched what do I know: If every item on the intake side has been taken care of, check the exhaust for obstructions. In cars the issue tends to be a clogged converter, so I can only wonder if any annoying animals stuffed the exhaust with nesting. If no then there has to be something affecting pressure or flow. Is the fuel rail clean? Have all filters and screens have been identified?

2 sets of fuel injectors but all of them have verified to work

If they are both non-OEM then I am unsure that injector tests assure that they are working correctly with the bike's systems.

Fuel pressure regulator? Measure the pressure with a gauge?

[mr1roll]

Nope. Trying 2nd set replacement injectors tonight and will post but I am not hopeful. Ran great as it was, replaced, cleaned whole fuel system including pump. These injectors are a last hope before sell as is.

New injectors in. No start. I have d&d 4 into 2 so pipes are not near blocked. Going to sell as is Richmond, VA area