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lazyeye

Surging/Bogging

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2014 VFR800F/D. 42000 miles.

Starting about 4000 miles ago the bike started bogging down and then surging. If I'm maintaining throttle (like on the highway) it will start losing power even though I'm holding a constant position, then if I move the throttle its like it realizes where it's supposed to be and surges back to that position. It stopped doing it for about 3k miles after I had the full service done, but recently started doing it on a trip.

I thought bad gas so I ran the tank nearly empty (the condition got worse as the tank emptied), refilled it, and then it started doing it again 30 or so miles later.

I thought the Throttle Position Sensor might be going bad so I tapped into the system via my Power Commander 5. The PC shows that the throttle position (at least in my garage) works properly 0-100%.

 

The bogging/surging is kind of inconsistent so its hard to drop it off and say it does a thing when it doesn't do it all the time.  What am I missing?

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Hi lazyeye.

Sorry to here of your bike woes especially since it's a 2014 8gen. Nothing goes wrong with these bikes!!

 

Your symptoms sound like it may be a blocking/dirty fuel filter. Also adding to that might be a kinked breather hose which is so easy to do after raising and lowering the fuel tank. After a bit of riding and you open your filler cap, are you sensing any strong vacuum holding the cap down?

 

Assume you're not seeing the Fi Light coming ON or any flashing code? 

 

On the last service you had done do you suspect that tank may have been raised, possibly to replace the air filter or any other reason?

 

As per the photos attached. Have a very good look at where the Breather Hose small to large adaptor is located. If it's hidden further inwards that could mean a kinked hose. It needs to be very visible on the R/H side.

Good Luck hope this helps, keep us posted.

 

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The last maintenance was spark plugs, valve adjustment, air filter replacement... pretty much everything. The tank had to come off to do that work. I'll have a look and see if the breather hose is kinked. I don't detect any vacuum in the tank (its easy to open up just like usual) and there's no codes or warning lights showing up. I've heard that the charcoal filter can eventually get clogged up and cause running problems, is that real or is it an old biker story?

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8 hours ago, lazyeye said:

The last maintenance was spark plugs, valve adjustment, air filter replacement... pretty much everything. The tank had to come off to do that work. I'll have a look and see if the breather hose is kinked. I don't detect any vacuum in the tank (its easy to open up just like usual) and there's no codes or warning lights showing up. I've heard that the charcoal filter can eventually get clogged up and cause running problems, is that real or is it an old biker story?

Did this issue happen before Or after the last Service?

Does your bike have the Evap canister? Can't imagine how this system could cause your issues anyway. If the canister became blocked it could possibly effect the breathing of your tank.

Feel may you need to isolate the Fuel Filter, your issues are very much symptomatic of a dirty filter or fuel pressure issues. Maybe other members might have some ideas.

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The issue happened before I took it in for service and was independent of the last time I raised the tank. It was fine for about 3000 miles after the service, that's what really confuses me. My bike has the evap cannister, I've been too lazy to figure out how to properly eliminate it.

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1 hour ago, lazyeye said:

The issue happened before I took it in for service and was independent of the last time I raised the tank. It was fine for about 3000 miles after the service, that's what really confuses me. My bike has the evap cannister, I've been too lazy to figure out how to properly eliminate it.

You can simply unplug the electrical connector to the Evap Control Valve Solenoid and give your bike a good run, see how it goes.

Still thinking your Fuel Filter, may be an issue. You may have to try a fuel pressure and flow test as per the Service Manual.

Perhaps this is something you could have done where you have your bike serviced, they should also have good ideas of what to check based on your symptoms.

Is there anything strange going on with your Power Commander? How hard is it to disconnect, and have your bike running in a stock standard situation for trial?

 

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On 7/1/2020 at 1:41 PM, lazyeye said:

The issue happened before I took it in for service and was independent of the last time I raised the tank. It was fine for about 3000 miles after the service, that's what really confuses me. My bike has the evap cannister, I've been too lazy to figure out how to properly eliminate it.

Any update on your bike? I'm still thinking it's a Fuel filter or pump issue. Maybe with all the country tripping you've done you may have picked up some dirty fuel along the way.

Keep us posted.

Cheers.

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The shop has it. So I'm bikeless for the moment 😞 I'm probably going to borrow my mom's Vulcan 500 for the meantime.

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1 hour ago, lazyeye said:

The shop has it. So I'm bikeless for the moment 😞 I'm probably going to borrow my mom's Vulcan 500 for the meantime.

Hope the bike shop gets it sorted ASAP for you. Keep us posted with what they find.

Vulcan 500, that would be a very different beast to the VFR!! Go easy on Mom's bike!:fing02:

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Any ride beats a drive....  😎

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I have a 2004 Vtec that is doing the same thing, reading through this tread I'll double check the breathers etc, however mine in factory, no power commander or map change.  So whatever it is its hard to diagnose.  I'm keen to see how you get on and what's found.

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1 hour ago, Damanisin said:

I have a 2004 Vtec that is doing the same thing, reading through this tread I'll double check the breathers etc, however mine in factory, no power commander or map change.  So whatever it is its hard to diagnose.  I'm keen to see how you get on and what's found.

While your VTEC shares a good amount of DNA with the 8th gen, it has its own issues with fueling and a very different ECU that's at least a decade behind the 8th gen's. The development of the VTEC happened in the late '90's when emissions regs were tightening and maybe the electronics were not as refined as today.  The AFR's were tuned to be very lean, to the point where it could be too lean under certain conditions.  You can search through the forums for remedies owners have instituted over the years.  In my case I used a Power Commander to adjust the fueling, and with an injector cleaning dispensed with those issues. These days I'd probably get a Rapid Bike  module vs a P.C. and let it tune itself to a bit richer AFR and see what you get.  If you still have the PAIR system be sure the valves are clean and there are no leaks in the system. 

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2 hours ago, Damanisin said:

I have a 2004 Vtec that is doing the same thing, reading through this tread I'll double check the breathers etc, however mine in factory, no power commander or map change.  So whatever it is its hard to diagnose.  I'm keen to see how you get on and what's found.

Agree with what Cogswell has suggested. But first check/replace your Fuel Filter, your bike is now 16 years old, hesitation, slight loss of power or surging at constant highway speeds is a good sign of a Fuel Filter issue.

 

Could you have recently picked up a bad batch of fuel? Condensation in your tank? Keep away from Ethanol blended Fuel if you can avoid it.

 

The 6gen does not have the same tank breather issue as the 8gen, so don't worry about the breather.

Cheers.

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