Running rich

I have a problem with my 5th gen running very rich, and economy suffering.
I'm down about 60 to 80km less per tank.
And my friends reckon that I leave a trail of black smoke after apex.
I have also smelt it for a little while that it's running richer then normal.
I will start pulling things apart next week if I get a chance, and check sensors for any faults.
I have no FI light faults, so it won't be an open circuit, maybe just reading too cold or too high pressure.
Anyone have any other ideas on what to look for?
BTW, I have a PCIIIUSB, open Staintune, Delkevic headers, coil on plugs, O2 and pair valves eliminated and a K&N filter. Filter box is standard.
I rebuilt my TB's not too long ago and engine temp is normal.
Nothing on the bike was changed or modified lately and it was running normal before.
It still goes fine, but it feels like it's slightly down on power all round.
When cold it splatters badly between 3000 and 5500rpm until it reaches running temp, it did not do this before.

 

Fuel pressure regulator? Has a diaphragm in it which can split and will dump raw fuel through the vacuum pipe. If the vacuum pipe also develops a leak you will end up with higher fuel pressure in the rail (vacuum signal is used to reduce the fuel pressure when the vacuum level increases so the relative fuel pressure vs the intake pressure remains constant).

 

Thanks Terry, I will read the relevant pages in the workshop manual to see what I can do to check.
I can also smell raw fuel when I shutt her off, but can't find any leaks.

 

The simplest check would be to take off the vacuum pipe at the FPR and check for liquid fuel; should be bone dry. You could also turn the ignition on to prime the fuel pump and see if there is any leakage from the FPR.

 

If checking out Terry's guess doesn't reveal anything I'd bet on one of the four injectors being stuck open (to some degree).

An injector can occasionally (slowly) become "fouled" by a buildup of debris (fuel varnish?) so that when the 12 volt electrical power is released (by the ECU after each engine cycle) the spring in the injector (combined with fuel pressure) cannot (immediately) return it to fully closed. So the injector's performance becomes erratic.

 

Thanks boys, I'll investigate this week if I get a chance.
My three daughters are keeping me busy lately.
The TB's were rebuilt about 20,000km ago, including getting the injectors flow tested and matched.
I don't use ethanol fuel or any of the cheap low octane ones.
Pulled the plugs and they all seem rich, so whatever the problem, it's affecting all the cyliners.

 

a bad engine temp sensor can "think" the bike is cold and add too much fuel, and a bad thermostat is another suspect.

 

I did a bit of digging around today with my limited time.
With the vacuum line off the fuel pressure regulator, and letting the pump prime there is no fuel coming out and the line looks dry.
All four spark plugs are very black, No. 4 less so.
Engine temps are normal, it starts first go as always and warms up as fast as it ever did.
Idle speed is normal, higher when cold, and settles once warmed up, all vacuum lines hold vacuum.
I will look at air temp sensor and MAP sensor if I get a chance.

 

If it stops spluttering when the engine reaches working temp I would probably guess that the water temp sensor is broken. The air temp doesn't change, or the pressure, so they shouldn't just stop interfering. But I'm not sure if the 5th gen has two water temp sensors (as the 6th gen does), and you have no VTEC to check if the sensor works.

If there were fuel in the vacuum line from the FPR it should mainly make the cylinders connected to the FPR run rich, not all 4. On a 6th gen that is cylinder 3 and 4, if I remember correctly. Don't know which on a 5th gen, but should not be all 4. It is possible that the FPR is broken in another way, so that it just don't regulate the pressure but doesn't leak fuel. You can measure the fuel pressure at idle to check if it works properly, but you need some extra hardware to do it.

How did you do the PAIR removal? Complete removal or just a blocked air hose? Could also be a broken PowerCommander.


I had the exact same symptoms on my 6th gen. I fixed it by changing spark plugs, changing thermostat, completly remove PAIR and changing FPR. I also had no fuel in the vacuum line, but changed it anyway since the cost wasn't that significant. It still smells funny from time to time, and there is soot in the exhaust but my fuel consumption was over 47 mpg (US) in Norway with full packing so I guess it's alright.

Oh, right, forgot. Have you checked your electrical connections lately? I had a suspected high amount of oxide on the (two) main earth points, as well as the connectors to the injectors and ignition coils. Did those at the same time as I removed my PAIR valves.

Edit: I have no idea why I translated the fuel consumption to US mpg when you're from Australia? It was below 5 liters per 100km.

 

You're right, FPR vacuum is only connected to cylinder 3 & 4, so it's not that.
All my electricals were redone and upgraded a while back, including getting rid of the earth block connector.
Everything associated with PAIR valves was removed and blocked including plates with sealing agent.
I will check to see if there's a second water temp sensor, but I don't think there is.
The air box temp sensor is a pain in the arse to check, as I will have to remove air box.
I'm also staring to suspect PCIII. I might have to remove it to see.
I'm using around 7L per 100km, and it doesn't change much if taking it easy or fanging it.
Thanks for your input.

 

I've had trouble lately with my engine temp sensor connection being corroded. The display did read - - and it went through a tank of fuel in no time . If the ecu thinks the engine is cold it overfuells .

 

Have you tried reloading your map into the Power Comander? Perhaps it had a glich and is the culprit.

 

Yes, I've tried a different map as well but no change.
Even sitting on the stand in neutral, if I give it a quick 50% throttle rev, exhaust gas is black.

 

How fast did this happen? Was it a gradual thing that you started to notice or was it all of a sudden?

 

It happened over a relatively short time.
I only ride my bike once a week, I'm pretty much in tune with it and notice small changes straight away.
I was riding with friends, and when we stopped for a coffee they mentioned that they could tell exactly how I was riding, because they would see my brake light go off followed by a little tornado of black smoke from my pipe.
I'll disconnect the PCIII for next ride and see if it makes a difference before I tear into the TB's.

 

I actually forgot that I enabled the accelerator pump feature, I'll start by disabling it and using the less agressive stock 00-01 map and see how it goes.

 

Went on a 150km ride today after disabling the accelerator pump feature and loading the stock 00-01 map.
The black puff when blipping the throttle is gone, I'm guessing that was the accelerator pump and I can't say it feels any different performance wise.
But economy is the same, around 7L per 100km, or 300km per tank.
I'm satrting to suspect a badly seating valve, just a gut feeling, but I'm seldom wrong on gut feelings (probably from 42 years of fiddling with motorcycle engines).
I will do a wet/dry compression check when I get a chance to see what I find.

 

Trouble shooting can be a pain in the ass. Doing 1 variable at a time is the key. And following you gut feeling too. That works well for me too.

 

Interesting observation today 0n a 150km ride.
Still haven't got to look in depth at anything, but noticed today that the engine temp never got over 76*C (168F) while on a spirited ride.
It was a tight windy road, and engine revs were between 5000 and 9000rpm most of the ride, air temp was around 20*C (68F).
It sits around 84*C in light traffic, but once I get clean air and start having fun it drops.
Probably why I haven't noticed earlier.
That seems a bit cold to me, thermostat was replaced 15,000km ago.

 

My problem is that when I get a bit of spare time to look at things, I grab my leathers and go ride instead.