kaldek

It was the black and white wire, coming from the Bank Angle Sensor and going to the relay on the left side of the bike. It took me awhile to find that wire...I had to cut all of the heat shrink and tape on the wires, and finally found the one that was causing my issues. I twisted the wires together and fired the bike up right away.

So, it's fixed?

Is the flat spot at Wide Open Throttle (WOT) or just when cruising?

Any updates on this problem? We'd like to know what the fix was.

It's not your ECU. The ECU gets is power *from* the clicking relay, so your issues are more fundamental. It actually sounds like bad electrical contacts to me, either on the ground or positive side.

Check the blue connector first. The blue connector on the left-side of the bike connects the main harness to the sub harness and includes the ground from the sub harness. This needs to be cleaned up, but a direct connection from the sub harness ground to the frame is recommended for the 2003 bikes.

You also should check the ground block at the front of the bike (wrapped inside electrical tape) under the front fairing - I recommend removing this fairing first. Unclip the block and make sure all the points are clean

Next check the main ground point where the ground wires bolt to the frame - it's just under the tank on the left-hand side, just forward of the battery tray.

Last is the main ground block on the main wiring harness. This is another plastic square wrapped inside the electrical tape, between the left-side main frame spar and the rear head.

Also check and clean all fuses (right-front side of bike under front fairing) and the main 30 amp fuse which is connected to the battery in a small plastic fuse holder. These are notorious for failing.

Yes. The bike did start, but I have not been able to replicate it since. I was blowing a fuse earlier, could it be a bad wire? I replaced the relay, and still no cigar.

Could well be a broken wire or one damaged from whatever caused the original short (i.e. it overheated before the fuse blew). Check the resistance on the wires that go between the relay and the bank angle sensor.

By the way, the Bank Angle sensor fuse provides power to the Engine stop switch and bank angle sensor. The engine stop switch provides power to the engine stop relay, as well as to the starter button.

Lastly, the ECU does not take its power via this 10 amp fuse, it takes it via the Main 30 amp fuse near the battery, but that circuit is switched on by the engine stop relay.

Your problem is either:

1. The wiring between the engine stop relay, bank angle sensor, and ground (Red Yellow, White/Black and Green wires); OR
   
2. The wiring between the engine stop switch and engine stop relay (Red/White and Black/White wires); OR
   
3. The engine stop relay
   

You can try a couple of hotwiring tests as well. Unplug the bank angle sensor and bridge the Red/yellow and Green wire terminals. That will bypass the bank angle sensor at least to see if that's a problem. You can also separately (in a different test) hotwire the Red/White and Black/White wires to bypass the engine stop relay, just to get the bike to start. Sometimes it feels good just to test that, to know your ECU isn't fried.

I'm getting frustrated as I'm not seeing any results. I replaced two relays, one by each indicator...and nothing.

Why would the fuel pump prime before, if the only thing I did was stick a wire down the black and white wires connection? It wasn't grounded or connected to anything else...just stuck down the hole.

OK maybe the wiring advice is wrong. Quite possible! If all you did was stick a wire down the hole, then the problem could just be really poor connectivity or the relay being mechanically damaged. Possibly the wires themselves are also damaged. Did the bike actually start after you stuck a wire into the relay?

Try this (assuming you meant 86 when you wrote 88 in your post):

Pin 30: Red/White wire

Pin 86: Black wire

Pin 87: Black/White wire

Pin 85: Red/Yellow wire

I *think* that will work.

For reference, the stock relay wire colours and functions are:

Red/White - main +12v feed

Black/White- switched output to ECU

Black - 12 volt switch command from Engine stop Switch

Red/Yellow - Switch ground circuit to bank angle sensor

The comments about the Dynojet Optimizers being prone to failure were making me somewhat paranoid.

Yes, the term "optimisers" is not exactly accurate. They renamed them because many newer model bikes don't fall for the resistor-in-the-heater-circuit trick. So, Dynojet have two products - one is the resistor, and the other is an actual optimiser but they call them both the same thing.

What the real optimisers do is take the O2 sensor signal and mess with it, so that when the bike's ECU thinks it's hitting 14.7 AFR it's actually hitting about 13.6 AFR. I believe they're simple voltage dividers which convert a signal of 0.75 volts from the O2 sensor into about 0.500 volts (which denotes 14.7 AFR). So the bike ECU sees 0.5 volts but in order to see that number it actually has to richen up the mixture so that it's *actually* creating a 0.75 volt reading from the O2 sensor. They do not offer this product for the VFR800 because the ECU in our bikes is so brain-dead it's easy to fool. In fact I think all the Honda systems are still dumb as dog crap. If you go to the Powercommander website, install instructions for Honda bikes will say "plug in O2 optimiser, you can then leave the O2 sensor disconnected or remove it from the exhaust". However for a modern Yamaha bike, the install instructions will say "plug the optimiser in-line between the O2 sensor and the ECU". Subtle difference, no?

For those bikes, the Powercommander instructions will also say stuff like "don't tune any cells between 0 and 15 percent throttle and 0-6,000rpm". However, since the Honda is, as I say, brain-dead you are actually able to tune the Powercommander in those ranges. So I guess the Honda stupidity kind of makes it easier to tweak the bike...

There are more advanced systems on the market (not from Dynojet) which replace the narrowband O2 sensor with a wideband one, but include a calculated narrowband voltage output. These are nifty for engine tuning whilst keeping the closed loop capabilities of the stock ECU in place.

Does that make sense?

Well, the O2 eliminator resistor is connected to the heater circuit. The resistor is basically fooling the ECU into thinking the O2 sensor is not up to temperature, so it never goes into closed loop mode.

if the resistor failed and went open circuit you would get an OS sensor heater error (error 23/24). If the resistor failed and shorted, that would trip the ECU fuse. If the resistor failed to the point where the ECU thought the O2 sensor was heated up, you would get an O2 sensor error (error 21/22) when the bike went into closed loop as it would see an open circuit.

The most likely scenario would be getting an error code 23 or 24 if the resistor failed.

For torque wrenches, I buy "Teng" brand. Good prices, and made in Taiwan so the quality is high.

Your issue isn't the pump it's the ECU. The ECU decides whether to power the pump, fire the injectors and the coils. If you turn the key to ON and the FI light doesn't come on, the ECU is not starting up. The fact that you're saying the bike will crank when you hotwire the fuel pump but won't start means the ECU isn't "on".

Check your kill switch first. The kill switch controls the Engine stop relay, which is what provides 12 volts to the ECU, injectors, coils and fuel cut relay. The ECU is what powers the fuel cut relay.

The "click" from the front left will be the engine stop relay. Sounds like either that relay is shagged or the kill switch is shagged. I suggest hotwiring the engine stop relay so that you provide power from the Red/White wire to the Black/White wire.

Note that the Engine stop relay also won't activate unless the bank angle sensor is working (Red/Yellow wire that acts as a ground for the Engine stop relay). So, while the ECU is what controls the fuel cut (fuel pump) relay, the Bank Angle sensor is what enables the engine stop relay.

Ok, I finally got the bike put back together, and now when it starts it idles about at the right speed then as it get warmer the idle increases until the it is running at almost 3000 rpm. What do I need to check?

You may find that your base idle speed is too high. When the engine is cold the air flow is controlled by the fast idle wax unit, and as it heats up the air bypass plate is controlled by the idle speed screw. At the same time as the fast idle wax unit is disengaging, the ECU is leaning out the mixture.

I'd let the bike warm up and then adjust your idle speed screw so the rpms drop to 1200. Then, let the bike cool down overnight and repeat the warmup cycle to make sure everything is OK.

If the idle speed won't drop even when you adjust the idle speed screw, you've stuffed something up around the fast idle wax unit area of the throttle body and need to have a look. Could just be something pinched or jammed in there.

Well that's good news to hear that Honda will cover it!

Make sure they put a smart guy onto this job, because removing and replacing the main harness is very fiddly, and cable routing is important. As BaileyRock found out, they can end up pinching wires and all sorts of nasty stuff if they do it wrong.

Good old Staintune. When my original-design system cracked they re-welded it for free. I now have the version 1.5 design which looks a lot like what they have gone back to.

OK. What this means is that the ECU is providing a path to ground from the fuel cut relay. I initially said that the relay is not a switched ground controlled by the ECU, but it is.

The only way that the fuel cut relay is going to activate is if the ECU is powered up, and has commanded the relay to be on.

At this point this means that either the ECU is faulty (extremely rare) or that the power feed to the ECU is messed up and causing the circuits within the ECU itself to pass electrons in a manner they were not designed for. That is also pretty rare on the 6th-gen.

Are there any other VFR owners from the forum near you where you could drop your ECU into their bike? It would need to be a 2002-2005 model. Sebspeed is in New York, in Cairo 160 miles away. Maybe ask if he's willing to help out! I would be cautious about putting his ECU into your bike, in case your problem is related to over-charging - which can fry ECUs.

At this point I do not believe it is the sub harness failing. By removing the ECU, you have cut the path between the sub harness and main harness (ECU is connected to main harness), so wherever the problem is, it's related to the ECU or wiring to the ECU.

Damn that is CHEAP! I spend $3800 on my wreck (but then all bikes are way more expensive in Aus).

Also, when I say "the wiring harness" being the likely problem, it can either be the harness you just had replaced or the main harness. It's more likely to be the front harness I think, as this is where all the wiring for the relays is, and is where the main black/white 12 volt feed comes from. If that blue connector barfs or short circuits, it would create the exact problem you have.

OK, so with the kill switch off and no whine, this means the basic 12 volt circuit feed to the ECU is working. When the kill switch is ON, it provides power to the front-left relay (engine stop relay) under the front fairing. From there, there is a white/black wire which goes to MANY locations on the bike, one of which is the ECU to provide power to it. Other locations include all the injectors, Fuel Cut Relay, Fuel pump, PAIR solenoid, EVAP solenoid, all ignition coils, intake "flapper" valve, and O2 sensor heaters. These devices are all switched on and off by the ECU by using switched grounds, except for the fuel pump which uses a relay.

But here's where it gets interesting. The fuel pump is powered by 12 volts fed to it from the fuel pump relay (brown wire). This relay should ONLY be active when the ECU is powered up. For some reason, your fuel cut relay is on permanently which means that the brown wire going into it has 12 volts on it even when it shouldn't. This is why it's a good test to remove the ECU now - if it still whines with the ECU out, the wiring harness is absolutely the problem.

this thing has never let me down...(dunno where I would buy one, Ive had it for years)

I use one of these - it has NEVER failed to remove an oil filter, and fits nicely onto the VFR. Well, mine has a handle included as part of it but you get the idea.

I'm not sure yet what these will prove, but they're easy and will help me choose some further direction for you:

1. Set kill switch to STOP. Turn key - does fuel pump still whine?
   
2. Set kill switch to run. Remove ECU. Turn key - does fuel pump still whine?
   

Get back to me with results.

I'm concerned about the Reg/rectifier. Don't know how to test that.

Fault finding diagram is your friend!

Wow that's some seriously messed up problems. I think you need a new wiring harness! You can find them on eBay quite cheap - well under $100 usually.

Hey mate, sorry to hear your problem has returned. You willing to do some diagnosis again like last time?

Can you confirm that your FI light comes on and then goes out after about 2-3 seconds when you turn the ignition on and have the kill switch set to run?

I came from a very nicely outfitted 95 FLSTN which had the perfect Harley shake so of course the 1200vfr seemed butter smooth throughout the rpm range. wouldn't engine problems trip one of the many sensors causing a fault code?

LOL. Honda motorcycle ECUs are brain-dead. The sensors literally have to be disconnected before you'll get an error. It's actually really pathetic.

The next bike I buy (whenever that is!) will have full OBDII capability.

it was that one together with a molten wire to the ecu.

Wow - can you tell me what the colour of that molten wire was? It's very strange that you can't kill the engine anymore. Does turning the key off work, or is the problem just with the kill switch?