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Vacuum leak???

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First time on forum for me so please be patient. I have a 99 bird that has ran like a dream for years. The other day I was riding and outta nowhere started running super lean and would not idle. I've got spark an fuel. Put a new set plugs in. Bike will start but will not idle. Runs very rough until you rev to higher rpms. Eventually fowls plugs. New fpr, wires, etc. gotta be a vac leak. Having problem locate leak. Any advice?????

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Fouling plugs; sounds like it's running rich, not lean, or has a spark issue.  New FPR, but check it anyway; pull the vacuum hose off and make sure there's no fuel coming from the FPR when you turn the key on.

 

Is it just fouling just one plug or all of them about evenly?  Does the FI light come on or flicker?  Sometimes it'll dimly flicker and not be real obvious.  Have you checked, cleaned, or eliminated the test connector on it?  If it hasn't been done there's a good chance it's starting to go bad.

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Thank you for your replies. Checked fpr no fuel in vac lines. And yes I meant running rich. It fowls random plugs in random order. No fi light. Have taken harness apart from front of tank to the computer. Infamous "plug" and all other connections in tip top shape. No corrision. I have spark and fuel to all cylinders.  I have spent many hours and $ trying to diagnose this issue. Wondering if I've been overlooking a simple vacuum leak. Wondered if anyone else has had issues with vacuum leaks and if there is a common area on the bird they can occur. 

19 hours ago, superhawk996 said:

And welcome to the nuthouse.

 

22 hours ago, blackhawkxx said:

What about the fuel pressure regulator? 

Checked and good. No fuel in vac lines

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Basic scenario with fresh set plugs= start bike, bike starts but no idle, turn idle adjust all way up and will barely idle, rap the throttle bike stumbles until about 3-4,000 rpm then smooths out, if I open throttle all the way the bike will not hit the rev limiter. Bike runs in this manner until the plugs go. Pull the plugs and they're wet and black. 

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a few possibilities that are easy to check,maybe a weak spark.is the battery charging ok?   

check the connectors going to the coils.

the auto choke,enrichment system may be sticking.

i have a 99 as well and havnt had a vacuum problem with it as yet.  

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3 hours ago, poida said:

a few possibilities that are easy to check,maybe a weak spark.is the battery charging ok?   

check the connectors going to the coils.

the auto choke,enrichment system may be sticking.

i have a 99 as well and havnt had a vacuum problem with it as yet.  

The auto enrichment is handled by separate components, not one 'auto choke'.

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A vacuum leak would cause a lean condition, unless that leak is in the hoses going to the MAP sensor.  My guess is that, or a sensor that's gone bad, or maybe wiring to the coils causing a weak spark.  Since you say you've gone through all the wiring I'll stick with a sensor fault.

 

A sensor that died or got disconnected should trigger the FI light and set a fault code, but one sending a wrong signal might not.  The manual gives specs for testing the BARO, MAP, and TP sensors; you could start by checking those.  The rest of them have no test procedure listed, but there may be a way to test them I don't know of.  Other thoughts would be the automatic fuel petcock, if it can fail to where the vacuum hose is sucking gas through it that would cause a rich condition but I think the hose goes to just one cylinder; do check tho.  Maybe a block in the fuel return from the FPR to the tank; kinked hose or a failure in the FPR is all I could figure that would stop the flow.  If the FPR was replaced after this problem started it's unlikely that it's the cause.

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If it has a Power Commander or any other tuning device take that off and see if things change.

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21 minutes ago, superhawk996 said:

The auto enrichment is handled by separate components, not one 'auto choke'.

i had one of the plungers sticking on mine a few years back.fouling number 4 plug and backfiring when closing throtte

 

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Ah, I think those are what Honda calls 'starter valves'.  The book doesn't explain what they do or how they work and I can't tell from the pictures.  Never dug into them on a bike to see.  I assume they're actuated by the wax unit.  I can't see how they can do anything for fuel flow and appear to control air flow.  Either way it doesn't appear they could do enough to cause major run problems like Indy's having.  If they do control fuel then maybe, but they'd have to all be stuck.

 

Do you know what exactly was sticking it and do you know what they actually do?

15 minutes ago, poida said:

i had one of the plungers sticking on mine a few years back.fouling number 4 plug and backfiring when closing throtte

 

 

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49 minutes ago, superhawk996 said:

Ah, I think those are what Honda calls 'starter valves'.  The book doesn't explain what they do or how they work and I can't tell from the pictures.  Never dug into them on a bike to see.  I assume they're actuated by the wax unit.  I can't see how they can do anything for fuel flow and appear to control air flow.  Either way it doesn't appear they could do enough to cause major run problems like Indy's having.  If they do control fuel then maybe, but they'd have to all be stuck.

 

Do you know what exactly was sticking it and do you know what they actually do?

 

starter valves sounds about right.yep activated by the wax unit.i think they restrict air,hence runs rich when cold.once the wax unit heats up the starter valves,or what i called plungers move back letting more air through.not sure what caused one on my bike to stick.i had shipped it back from europe and when i picked it up from the shippers depot it was running like a pig.took me a while to find out why but eventually tracked it down to one of the starter valves not opening when warm.i had a post on here back then asking for any ideas what what causing the rough running and sooty plug.will have a look for it.found it

http://www.cbr1100xx.org/forums/index.php?/topic/73866-running-rich-in-no-4-cylinder/

 

Edited by poida

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Thank you everyone for your replies. I will continue trouble shooting and let you know what I find. All great suggestions!!!!!!!

On 11/5/2017 at 10:23 AM, superhawk996 said:

A vacuum leak would cause a lean condition, unless that leak is in the hoses going to the MAP sensor.  My guess is that, or a sensor that's gone bad, or maybe wiring to the coils causing a weak spark.  Since you say you've gone through all the wiring I'll stick with a sensor fault.

 

A sensor that died or got disconnected should trigger the FI light and set a fault code, but one sending a wrong signal might not.  The manual gives specs for testing the BARO, MAP, and TP sensors; you could start by checking those.  The rest of them have no test procedure listed, but there may be a way to test them I don't know of.  Other thoughts would be the automatic fuel petcock, if it can fail to where the vacuum hose is sucking gas through it that would cause a rich condition but I think the hose goes to just one cylinder; do check tho.  Maybe a block in the fuel return from the FPR to the tank; kinked hose or a failure in the FPR is all I could figure that would stop the flow.  If the FPR was replaced after this problem started it's unlikely that it's the cause.

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3 hours ago, Indybird said:

Thank again!! Love this site. Everyone very helpful. When I get my girl running I'll let you what it was!

Please do because you never know who else that info might help.

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Stuck fuel injector?  I had one stuck closed, and acted like you are saying (except the running rich part.)  If one was stuck open, it would pour fuel that could never possibly fire yet not be enough to hydrolock.  Maybe the injector has enough umpf to open but not enough to actually cycle.

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But all cylinders are rich so probably not an injector.  There's either excess fuel or a lack of spark energy to all 4.

 

Pretty unlikely, but make sure something didn't get sucked up into the air intake blocking the airflow.

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On 11/8/2017 at 9:34 AM, superhawk996 said:

But all cylinders are rich so probably not an injector.  There's either excess fuel or a lack of spark energy to all 4.

 

Pretty unlikely, but make sure something didn't get sucked up into the air intake blocking the airflow.

...mice...

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