Fuel being dumped down the cylinders

For Reference: Bike is an 04 VFR non-ABS - stock + K&N air filter


I am having a fuel related issue that I'm not sure how to track down right now. I first noticed it through the drop in gas mileage over the last 4-5 tanks of gas. I usually get somewhere between 42-44 mpg, occassionally reaching into the 38's when I rider her hard. I had a few tanks in the 38's which I didn't think much of but then it dropped down to 36 and now it is all the way down to 31 at the last tank. Something is going on and not just more twisting of the throttle. The last tank I took it really easy and didn't even hit VTEC at all. No PGM-FI light is on while the bike is running.

Here's what I have done:

Stick your fingers in the exhaust and they come out damp and very very black. Its dumping fuel like crazy down the cylinders apparently.

Pulled the front two plugs. They look very good. Mild amount of carbon at the end of the threads. The electrode looks like new with a nice sharp point and the porcelain has a very light tan color to it. Sounds perfect to me. I will get to the rear soon.

Shorting the system service check connector gives me 9 blinks on the PGM-FI light. This indicates a problem with the IAT sensor and makes sense as to why the bike is pouring fuel out the injectors. It thinks it is cold all the time and gives it more gas. Testing the IAT sensor and leads to it per the manual indicates that it is fine. Per the service manual I have a bad ECM.

I just find it hard to believe that I have a bad ECM and that I'm getting ready to be out $800 bucks for a new one. (Yes, there are other options such as a used one somewhere or an aftermarket one.)

So where else can I start looking for issues? I've thought about O2 sensors, a MAP sensor, ECT sensor, TPS sensor, or maybe even the Fuel Pressure Regulator. Funds are very limited right now. I've got most of the tools that I need to do anything I probably will need to and if I don't I at least have access to them. I can do the work to fix it but in order to do so I need to figure out what it is BEFORE I drop the money on whatever it is.

If you want to know anything else at all, please ask. I can make pictures available upon request of whatever is needed and I will be watching the forums like a hawk the next few days to try and get this all figured out so updates will be given ASAP.

 

leaking

The first gen 6 I worked on had this issue. The injectors leaked fuel , just a drip but enough, and would run under a load but at idle or shallow throttle it would miss. I was not sure of cause but always assumed it was water damage and from sitting.

 

I don't think that this would pertain to this situation unfortunately. The bike start fine, idles fine, and never ever misses or hiccups ever. I will definitely check into this though after other checks say everything is OK.

Here is the update as of today:

Fuel pressure regulator - Checks ok per vacuum test. Holds pressure with no leakage and does not have any fuel coming out of the vacuum line even under pressure.

MAP Sensor - fails map sensor output line connection test via multimeter- need to test with ECU test harness (Page 5-15 No on step 4 - voltage at 4.1V and not between 4.75V and 5.25V)

ECT Sensor - have not tested as of yet. looks like the fuel rail will have to come off to get to this sensor to test it.

TPS Sensor - Checks ok till ECU harness is needed to test further

O2 Sensors - next on the list to test, just had to take a break due to frustration.

IAT Sensor - Checks good per service manual multimeter test

Fast Idle Wax Unit - not sure how to test as of yet. Service manual doesn't say anything about it other than how to remove/replace. I think this is ok though because if it is cold out the bike will start fine with high idle until it warms up and then idle goes down to normal 1300 RPM.

I think that as of now, things are pointing to the MAP sensor being faulty. Does this make sense as to why it would be running very rich? Can someone answer as to how this sensor is supposed to be mounted? I beleve there is a single screw that goes into the bottom (right rear side) of the airbox that it should be mounted to. The screw is there on my airbox, however the sensor was not mounted there and just laying underneath the airbox.

 

the moisture in the pipes might not be fuel, it is a byproduct of the cat, if you were getting that much fuel in cyln you would burn your kitty cat out and would have restricted flo in your exhust and would feel loss of power.
32 - 38 mpg is the norm on mine.
try to test 02 sensors there are 2 seeing how air temp tested fine.

 

With regard to the MAP sensor;

Making Sense of Engine Sensors

http://www.associatedcontent.com/article/803331/adjustable_map_sensor_saving_fuel_in.html

The second one has more of a direct explanation of why you are running rich.

 

After a tank and a half to confirm... it looks like things are fixed. I replaced the MAP and IAT sensors just for the heck of it since the ECM had flagged them for some reason. I'm 99.9% sure the issue was the thermostat which was stuck wide open upon inspection. Engine was being allowed to reach operating temps and as such was pouring as much fuel as it could to get her warmed up.

Fuel was indeed getting in my oil. I drained slightly over a gallon out of the bike and the last time it was changed I had to put in 3.3 quarts to get her up to the full line. I'd say I wont have to worry about sludge in my engine for quite a long time now.

Thanks to everyone that helped out on this issue.

 

The bad part is. With that much fuel in the oil. You had to be washing the cylinders walls of it's oil. Not good for the rings or cross hatch or your bearings. Good luck.

 

I agree. I got to it quick so hopefully no damage was done. I had some darn good oil in there and upon smelling it after draining there was no gas smell in it. Hopefully the oil held up. There are no sound changes in the engine, no smoke from the exhaust, and no performance changes per the butt dyno. Time well tell if I'm screwed or not.