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I just bought a 2003 Honda Interceptor VFR800 ABS, it has 10,000 miles and for the most part runs okay until...

 

  • After the bike is warm (180F) it will stall and die.
  • It also will subtly cut-out around 5000 rpm (cruising speed).
  • After start-up I can smell a rich fuel mix from the exhaust.

 

As I begin maintenance and troubleshooting...

 

  • Is this an O2 sensor issue?
  • Faulty injector (no fuel injection warning light yet)?
  • Fuel pump?

 

Would purchasing a Dynoject Power Commander bypass any O2 sensor issue?

 

Thanks.

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Hi infjdesign.

You may have an issue with one or more injectors not properly shutting off, or possibly a ruptured diaphragm within your Fuel Pressure Regulator. Possible leaky Vaccum lines. An intermittent Fuel Pump could also be on the cards, do you ALWAYS hear your fuel pump prime for two seconds at ignition ON wether the engine is hot or cold?

 

Strange, your symptoms are certainly not of a bike that "for the most part runs okay!"

 

The O2 sensors shouldn't cause the radical issues you're having. The manual states with a faulty O2 sensor the engine operates normally, plus you said you don't have an Fi warning light.

 

Is your bikes exhaust smokey at all? Does it accelerate Okay? When you say it subtly cuts-out is that just a hiccup or does the bike completly stop running? Have you had these issues since the day you bought the bike or is this a very recent issue?

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Bummer to have a bike new to you have such problems.  Do you know the maintenance history of your bike? If you are not certain then there will be a bunch of things to check out. You say the bike is running rich - or at least smells that way. That by itself is not normal.  Have you looked at the air filter to see if there have been mice building a home in there?  This is not uncommon at all.

If the bike hasn't been well cared and sat unused for a long period of time then the fuel system should be looked at carefully. Is there any evidence of corrosion in the tank?

Do you know what modifications were done by the past owners? I'd check those things over carefully to see if they were done right.

 

Good Luck

 

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Thanks for the feedback.

 

I just purchased it on Sunday, July 15th, 2018. I blame myself for not test riding it further but the seller was in a rural part of Kansas and I wasn't nuts about doing a lot of riding on gravel roads with someone else's bike (at the time). It starts (cold) perfectly fine, no smoke at start-up, idles fine (cold), shifts, accelerates fine (cold). Once the engine temps warms up is when it becomes problematic.

 

I am going to start sweeping through it and replace parts during this troubleshooting process. I just purchased a Honda Service Manual from online and a Haynes repair guide. Ideally I would like to not have to replace things like the PGM-FI unit or any other electronics. It would be nice to know if this was a fuel system problem or an electronic/sensor/electrical problem.

 

My Triumph Speed Triple is my primary ride (though I did own a couple of CBR's before the Interceptor), but it is a paaaaaaaaaaain to work on, so beyond routine maintenance, I leave it to the pro's. I'm going to start replacing stuff like plugs, filters (air/fuel) and then move onto pricier items.

 

It's a fun bike (very unique power band) and I love the design (under tail dual exhaust, integrated fairing turn signals, narrow profile). I'll shoot a video when I get the chance and post it along with some pics. 

 

If there is anything else that comes to mind as to engine dying when warm, let me know.

 

Thanks everyone...

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Have you tried adjusting the idle adjuster to cure the warm idle problems? I do know that my 5G is sensitive to the idle speed being too low and can cut out when coming to a stop if that is not set high enough (usually 1400 works for me). The 6G has a cold fast idle mechanism comprising the the Wax Unit, which has coolant passing through it and elongates when hot, allowing the starter valves to rest on the idle adjuster screw. 

 

A possible reason for a cut-out at while riding (could happen at 5000rpm) would be the sidestand switch if that was loose or had a dodgy wire. 

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3 hours ago, MarkDetroit said:

Bummer to have a bike new to you have such problems.  Do you know the maintenance history of your bike? If you are not certain then there will be a bunch of things to check out. You say the bike is running rich - or at least smells that way. That by itself is not normal.  Have you looked at the air filter to see if there have been mice building a home in there?  This is not uncommon at all.

If the bike hasn't been well cared and sat unused for a long period of time then the fuel system should be looked at carefully. Is there any evidence of corrosion in the tank?

Do you know what modifications were done by the past owners? I'd check those things over carefully to see if they were done right.

 

Good Luck

 

I don't know the maintenance history of the bike. I believe I am the 3rd owner of it. As I mentioned it has just over 10,000 miles (very low for a VFR of this age, or any age), so I'm not sure if that's a good sign or a bad sign (has this bike always had problems, hence the low miles). The bike didn't have any mods except for a Corbin seat that allowed the previous owner to ride 2-up (in relative comfort). I immediately returned it to the stock seat and cowl and removed the passenger grab bars and popped in the tail fairing inserts.

 

I am going to install a tail tidy/tail-remover kit because I don't need 10 lbs. of DOT sanctioned equipment, when less will do.

 

A new air filter, fuel filter and plugs are on the way along with two new O2 sensors (knowing that they have a high failure rate so I'll go ahead and preemptively replace them). I'll see if that fixes the issue and then move on to any type of vacuum, sensor or relay that might be involved. After that it will be the injectors themselves...and so on.

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24 minutes ago, Terry said:

Have you tried adjusting the idle adjuster to cure the warm idle problems? I do know that my 5G is sensitive to the idle speed being too low and can cut out when coming to a stop if that is not set high enough (usually 1400 works for me). The 6G has a cold fast idle mechanism comprising the the Wax Unit, which has coolant passing through it and elongates when hot, allowing the starter valves to rest on the idle adjuster screw. 

 

A possible reason for a cut-out at while riding (could happen at 5000rpm) would be the sidestand switch if that was loose or had a dodgy wire. 

It's a 2003 so that makes it a 6th generation, if my Motorcyclist Magazine article is correct...or not.

 

As soon as I get home tonight I am going to do an idle test and see what happens to the standing idle as it warms up. When I rode it home yesterday the outside air temperature was around 100-105F (definitely toasty and yeah, it wasn't a "dry" heat). The engine temp hovered around 175-185F when I was going 75-85 mph. When I had to slow down at intersections and stop lights and over-rev to keep it from dying, that pushed it up around 215F. I definitely didn't want to cook the engine on my first ride home.

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Yes your bike is a 6th gen, first released in 2002 and in production until 2012.

 

215F is no problem; if the bike had a dial-type gauge for coolant temperature, that would be about 1/2 way. The maximum allowed by Honda is 252F. 

 

Your idle speed adjuster knob should be present on the right side, just above the clutch cover on the engine. Given the auto fast idle when cold, you should only adjust the idle when the engine is properly warmed. The 6G manual says 1200 rpm. 

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On our way to Custer last week, my 6th gen was indicating 236 at 85 mph in near 100 deg temps.  That's no problem for it - it ran fine for the 2,000 mile balance of the trip.

 

With a bike that done lots of sitting, bad gas / clogged injectors can be an issue.  Even if it's not your immediate problem, removing the injectors for a professional cleaning can be a big help to smoothing out power delivery (it's not all that hard on a 6th gen).  A clogged injector (or one that's not shutting off) will generally not set an FI code.   Also, draining the tank to the extent possible, then propping it up to concentrate what's left at the bottom will allow nearly complete evacuation of all the fluid.  If there's any water in there from condensation or phase separation from ethanol laced fuel, getting that out is also a help. 

 

Regarding the pros, a lot of Honda dealers rarely see VFR's.  It's almost as if they wouldn't know what it is expect for the logos on it.  IMO you'll find more knowledge here on the site than talking to a service advisor that's going to charge by the hour. 

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So I got home, brought it out and started it up. I let it idle for about 20 minutes and brought it up to about 180F. It idled smoothly, no hiccups or cut-outs though the exhaust still smelled rich.

 

When I went to throttle-up the motorcycle it throttled-up fine, clean/smooth revving up to 6000rpm...

 

The problem came when I released/returned the throttle back down...it died.

 

It restarted but I had to open the throttle to get it to stay running. (All of this was around 190F engine temp)

 

If I have the time I'll shoot a video tomorrow so there is a clearer idea as to what's going on with it.

 

Once again, thanks for everyone's input and feedback...

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Just curious if anyone has had any experience with a "fuel system cleaner" like Red Line Complete Fuel System Cleaner for Motorcycles?

 

After I drain the tank and replace the fuel filter, air filter and plugs I was thinking about adding some with my initial full tank of fuel to see it helps? Any risk?

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Most fuels contain cleaning additives.  Adding additional won't hurt for maintenance - however there's no substitute for removing the injectors and having them professionally cleaned.  I tried adding Seafoam and other cleaners with little effect.  After the injectors returned from RC Engineering the power delivery was noticeably smoother.  Now that I'm getting close to 30,000 miles I'm thinking of having them done again.  YMMV. 

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On 7/17/2018 at 11:40 PM, Cogswell said:

Most fuels contain cleaning additives.  Adding additional won't hurt for maintenance - however there's no substitute for removing the injectors and having them professionally cleaned.  I tried adding Seafoam and other cleaners with little effect.  After the injectors returned from RC Engineering the power delivery was noticeably smoother.  Now that I'm getting close to 30,000 miles I'm thinking of having them done again.  YMMV. 

Thanks for insight. Forgive me for my ignorance, but just by looking at the VFR's fuel system schematic, I'm assuming it has a "top feed/rail feed" injection system (as opposed to a side feed or hose feed system).

 

I'm also trying to assess the degree of difficulty with removing/installing the injectors myself once they are sent off for service.

 

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It's easy on a 6th gen.  After removing the air box,  you'll want to depressuize the system.  The fuel rail is on top of the throttle body and held on by 4 bolts.  Be sure to use some lint free cloth or something to protect the intake plenums from debris entering.  Once the bolts are out rock the rail back and forth gently to free the injectors from the TB and lift everything out as a unit.   Be sure to use some light oil on the o-rings on reassembly.  The injectors can be removed from the rail with a slight twist and pull.  Have a few rags on hand to soak up any excess fuel.  

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There is only a small volume of fuel in the lines so I would not be hung up on depressurising.

 

I can tell you from personal experience that fuel will happily gravity-feed from the tank into the FPR and down your leg if you just elect to pull that off. The only things stopping fuel draining into the intakes are the injectors, so if they don't shut off completely you'll end up with fuel in the oil. 

 

You should be able to flip the tank completely over onto the rear subframe (suitably padded) and pull off the fuel banjo without draining the tank. If you store the tank upside down off the bike the fuel cap should seal 100% and prevent any leakage. 

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That seems like a good sleeping position for winter 😛

 

I’ll be sending mine off for cleaning this winter when the bike sleeps. For now, bike is loaded up and ready to head out for some big miles this weekend. Hope the heat stays under control with recently

tightened hose clamps (that leaked before).

 

best of luck OP.  I still think it’s not

related to a fuel additive in the tank though. It sounds like a bigger problem then fueling, for now. 

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