Oil smells of Gas!!!

[Phil_RC_1]

I bought an 07 FZ6 a couple months ago, it had been down on both sides, one side was a low speed low side, the other it just got tipped over while parked. It has 16K miles. Mechanically seems perfect,,, except, I changed the oil when I got it home and it smelled of gasoline. Recently, I checked the oil level and it is slightly overfull and smells of gas again.

Any ideas? I'm thinking the worst and that it may be piston rings but I thought some of you may have other ideas of what to check.

 

[ChevyFazer]

If the piston rings were gone it would more then likely be smoking real bad, it's probably your mind playing tricks with you. If the bike runs good and has no real mechanical issues then I wouldn't worry about it, because there is no real way for a gas engine to dump fuel in the oil if it is running on all 4 cylinders. On carburated engines it's a fairly common occurance when the floats give out but on a efi engine, if there is gas in the oil then the bike should have a pretty serious problem with either fuel delivery or ignition and should be running like crap, you could pull all of your plugs and look at all of them to get an idea of what's going on in there, but if the bike runs good and smooth it's probably your mind playing tricks

 

[wrlomas]

On a caurberated motor the float can hang open if it gets gummed up. I have had it happen on my racecar and while sitting it leaked down past the rings and filled the crankcase with fuel. This is an explosion hazard and also could hydraulic and bend the rods. I caught it as I checked my oil before firing the motor. Rare but it did happen to me. It was sorta a perfect storm situation as my fuel cell was mounted high in the back and the motor was as low as I could get it in the frame so a siphon developed between the tank and the float. The fuel ran down the intake and leaked in thru an open valve then slipped past the rings. If I had fired the engine, at least it would have scuffed the bore as the oil film was washed off by the fuel or turned into a bomb in a worst case scenario. I assume your motor is injected but with the tank over the motor it is possible but not likely. Drain your oil into a clear glass jar and you could see the fuel piled up on top of the oil if there is enough in the crankcase. Although a tiny bit of fuel makes a lot of vapor and at 77 to 1 with air it is dangerous. Proceed with caution. Just my 2 cents.

 

[Motogiro]

I agree that if you were getting enough gas in the oil to see a big oil level change there would be a radical problem that would cause the engine to run really bad. If that is happening there is another cause.

 

[FinalImpact]

I agree that if you were getting enough gas in the oil to see a big oil level change there would be a radical problem that would cause the engine to run really bad. If that is happening there is another cause.

Temperature changes will vary the oil level ever so slightly as will time between drain back.

MORE likely is multiple short rides or starting it to warm and never going anywhere. During cold starts the ECM kicks in and adds more fuel (richens the mixture) to the burn to make it run well until it warms.

If your daily routine is to ride 10 minutes down the road and park it - let it sit, ride 10 min home, this would be a likely event for the oil to smell of gas.

But - a leaking injector could cause this too. Is the tank full rust? Has it been sitting outside most of its life? Tell us some details. . .

Also getting on the gas hard on cold engine would likely induce blow by past the rings. So are you naughty or nice to the FZ when its cold?

 

[SovietRobot]

It's more likely oil in the combustion chamber than gas in the oil.

Everytime my bike's been tipped over, it would smoke and burn oil that got spilled into the combustion chamber for a minute or so.

 

[Phil_RC_1]

Temperature changes will vary the oil level ever so slightly as will time between drain back.

MORE likely is multiple short rides or starting it to warm and never going anywhere. During cold starts the ECM kicks in and adds more fuel (richens the mixture) to the burn to make it run well until it warms.
If your daily routine is to ride 10 minutes down the road and park it - let it sit, ride 10 min home, this would be a likely event for the oil to smell of gas.

I bought this bike, primarilly for my wife (I have an FZ1 also), but I ride it more then she does. My commute is 40 minutes, when I ride it on the weekends, I'm usually out for at least 15-20 minutes, usually longer.

But - a leaking injector could cause this too. Is the tank full rust? Has it been sitting outside most of its life? Tell us some details. . .

I don't know much of the history of the bike, but the tank is clean. The "leaky injector" idea sounds like something I need to checkout. Seems it would give my symptoms and be similar to a leaky float valve on a carb'ed bike.

Also getting on the gas hard on cold engine would likely induce blow by past the rings. So are you naughty or nice to the FZ when its cold?

Never,,, Never,,, when cold!!!!

Now, How do I check/verify the injectors are good?


Thanx to all for the suggestions.

 

[Phil_RC_1]

If the piston rings were gone it would more then likely be smoking real bad, it's probably your mind playing tricks with you. If the bike runs good and has no real mechanical issues then I wouldn't worry about it, because there is no real way for a gas engine to dump fuel in the oil if it is running on all 4 cylinders. On carburated engines it's a fairly common occurance when the floats give out but on a efi engine, if there is gas in the oil then the bike should have a pretty serious problem with either fuel delivery or ignition and should be running like crap, you could pull all of your plugs and look at all of them to get an idea of what's going on in there, but if the bike runs good and smooth it's probably your mind playing tricks

Yeah, that makes sense. Most of the bikes I've owned over the years were carb'ed and more then one eventually had a sticky float valve. Since this one is EFI, I had no clue as to what may cause similar issues. The bike seems to run fine, good power, smooth and not smoking. I think FinalImpact may have it, I'll definitely run a couple tanks of Seafoam treatment to see if that helps. Anyway, I know our minds are easily "tricked" but I have three other bikes in the garage that don't smell like this.

Now, How do I check/verify the injectors are good?

Thanx for the suggestions and "reality check"

 

[ChevyFazer]

I'm probably wrong I know a lot more about carbs then efi systems but I would think that if a injector was leaking that would be cause by other problem with the injector, in turn maybe causing skipping or flooding of that cylinder. So in other words going back to what I was saying before the bike (I would think) should be running bad, like real bad, not always running 4 cyl bad. You should be able to pull your plugs to check and see if a cyl is getting more or less fuel that others

 

[FinalImpact]

Typical injector tests for pattern, rate, and leak come from having them removed and applying different loads to them.

A leak test is just that. Apply a constant 36psi and observe the injector does not drip OR the fuel rail remains are 36 PSI and doesn't drop. For home use this is hard to do as we have to take it apart to see it OR establish hold a pressure.

IMO an option would go something like this.

• Engine off.
• Attach a pressure gauge to the fuel rail.
• Insert an on / off valve between the pump and fuel rail.
• Excite the pump, get it to pressure and close the valve.
• Guessing here. . . but a good injector should easily hold pressure for 30 minutes or longer.

In normal use I would think that the pressure is bleed back to the tank. However, if you have a leaking injector, it could dump the fuel into the top end.
Does your bike have a CAT? If leaking, it would likely blow a dark cloud at startup followed by blue smoke from the gas rinsing the cylinder wall of oil.

Does it blow blue smoke? Does it blow black smoke?
Maybe 1st step should be to change the oil and disconnect the battery to reset the ECM and ride it for 40min. turning it off a couple of times while hot and then continue riding.

Got long - - sorry

 

[ebster1085]

I just read this entire thread, but before even doing so, my initial thought was a leaking/cracked injector. Check all the injectors where they enter the intake tract. If you see any residue or drips around the entry point, you may have a cracked injector. Even if you dont see anything on the exterior, you still may have a bad nozzle that is leaking which would cause the gas smelling oil.

 

[ChevyFazer]

Wouldn't the problems with the injectors that y'all mentioned cause the bike to run like crap? Either way I would pull the plugs first before messing with the injectors, the look of the plugs should be able to give you an idea of what's going on in the combustion chamber and wich or if a injector is acting up

 

[RCPMg33k]

+1 what ChevyFazer said.

 

[Marthy]

All I can say here is keep an eye on your oil level for a bit each time before you start your bike. Gas dilute oil density... combine that with a high revving engine... Kaboom! Has I understand you cycle is injection. Make sure you don't cycle your ecu (turn the key on/off few time without starting the bike) Start it right away when you turn the key.

If your injector is dripping a bit or don't close you might not notice it while the bike is running since at speed there open at about 60% cycle... you won't feel a difference in other word because they're open 0.6 second every second. (give and take)

Does it puff black smoke when you start it?

I bought a FZ6 throttle body assembly to fit on my 6R, I won't use it. I could ship you the injector if you want to try...

 

[ChevyFazer]

The reason I'm not so sure about a leaky injector is because he said there is no smoke, runs smooth, and no other mechanical problems

 

[YZF73]

Just my two cents ,

You have said that the oil level appears to have gone up, I found with my FZ6 that by checking the oil level in a different place (only slightly off level) to where I originally set the oil level (perfectly level surface) I got quite a high reading, when I moved back to the place I originally checked the level at, the reading was spot on.

Something else to consider, internal combustion engines have round bores (mostly...), however because of the thermal expansion of metal that occurs during engine operation the piston is made in an oval shape (only very slightly), this is due to the fact that there is more material surrounding the gudgeon pin than there is perpendicular to the gudgeon pin (if you see where I’m coming from?), this is done so that when the piston reaches operating temperature thermal expansion causes the piston to form the same shape as the bore, however this does mean that during cold start/running conditions you are not necessarily getting the gas tight seal you need at the rings, possibly increasing the amount of blow by (blow by always occurs to some degree, even in an engine that is fully up to temp), so it would be acceptable for some fuel to get into the engine oil over time.


The only problem I can think of that would really cause excessive blow by would be a damaged cylinder (possibly starved of oil momentarily at some point) causing a bad seal between the rings and the cylinder, if you have access to it, it might be worth checking the cylinder compressions as this gives a good indication of the condition of each individual cylinder, if you aren't able to get hold of the tools to do this, connecting up a throttle body sync tool may also give an indication through the vacuum readings.

As for the injectors, the FZ6 uses a batch firing sequence, and is programmed to switch to open loop mode at relatively low engine load/speed, to me this means that there is the possibility of excess (possibly liquefied rather than atomised) fuel hanging around, giving even more chance for fuel getting through into your crankcase if there was a ring sealing problem.


Apologies for the long post but I thought I'd throw all my ideas out there at once :spank:


Yamahaboyz

 

[FinalImpact]

^^
OK - Q? What if its more simple like a bad temperature sender whereby the ECM doesn't get good info?? Stays in open loop longer than needed?? Just thinking out loud.

OP - Does the temp gauge work and what temps are you riding in? Cold months will have a greater impact than warm months.


Chev, I hear you and I agree it should blow black smoke IF the fuel is present when its fired. But the pressure bleeding off over night could simply land it in the crankcase.
PS - during WWII, it was common practice to dilute the crankcase oil with AV gas so the engines could be started. Once warm it evaporates. My point; smelling it and diluting it enough to scuff cylinders and melt bearings is drops vs ounces...

OP - how often have you change the oil?

 

[yamihoe]

Drain your oil into a clear glass jar and you could see the fuel piled up on top of the oil if there is enough in the crankcase. Proceed with caution. Just my 2 cents.

take the oil and see if it lights lol

 

[YZF73]

^^
OK - Q? What if its more simple like a bad temperature sender whereby the ECM doesn't get good info?? Stays in open loop longer than needed?? Just thinking out loud.

Yes this is definitely a possibility, thank you for picking up on it :spank:.

I feel that this is unlikley as the OP would have probabily noticed that the coolant temperature readout on the clocks was giving strange readings (I know my bike runs at about 73-92 degrees C (sorry, were awkward in the UK ) while moving depending on the ambient air temp, maybe the OP can confirm this?).

The main thing that is troubling me about this is that there is no direct path for fuel to enter the crankcase except passing by the rings, even by over fuelling the cylinders the fuel still has to pass the rings to get into the oil, I can't think of any other route it would likely take?

Yamahaboyz

 

[ebster1085]

Wouldn't the problems with the injectors that y'all mentioned cause the bike to run like crap? Either way I would pull the plugs first before messing with the injectors, the look of the plugs should be able to give you an idea of what's going on in the combustion chamber and wich or if a injector is acting up

Had this problem with my car and it did not cause any noticeable change in the way the car ran, nor did it cause any smoke or smells. I noticed one day upon pulling my dipstick to check the oil level that it smelled of gas, so I started reading up. Read a thread about it potentially being a leaky injector, so I looked at the injector ports on the intake manifold, and long behold, there was some drips around the cylinder 4 injector.

Pulled the injector and it had a hairline crack on the nozzle which was causing it to leak. Swapped it out, no more drips, and no more smelly oil.