Blue fuel staining

[aaronk25]

My lower right cowl flap was covered in blue sticky stuff and I noticed it looks like it is coming from the intake on #3. It actually looks like its coming from around the oil return line but I think it's just all goopy around the intake/oil return fitting.

Anyone had this before? It's fuel, but when I had leaky tanks it was just a light staining this stuff is sticky.

[231flyer]

Check your engine driven fuel pump.

[aaronk25]

What do I check? Pump is located near case but staining is on intake at cylinders.

[N201MKTurbo]

It is possible that your fuel divider is not closing completely at idle shutoff and the fuel in the lines is seeping out through that injector nozzle after shutdown. If nothing else is wrong clean your engine and keep an eye on it, but don't loose any sleep over it.

[231flyer]

I had similar symptoms on my TSIO360LB engine.....fuel stains visible near the right cowl flap and streaking backwards.  On decowling discovered fuel trails near the cylinder bases and the various tubes and structures on the lower right side.  Visually checked the lines etc and all seemed normal.  Cleaned off the stains and ran the low boost fuel pump. The engine driven fuel pump was spewing fuel on the exhaust, the inner gasket/seal had failed.  I had just flown from TX to CO and was fortunate to have avoided an inflight fire.  Got the pump rebuilt by Mike's Metering in Tulsa.  Although the fuel pump was leaking it was functional enough to keep the engine running without experiencing roughness or anything obvious.  The fuel pump showed no external signs of leaking, it looked clean. After the visual inspection was unsuccessful at finding the source of the leak, my mechanic wanted to pressurize the fuel system. Turning on the low boot pump did the trick.  Easy but expensive fix......$750 for the overhaul and $500 for the labor.  

[manu damaschin]

I don't know about the M20J, but could it be from the fuel drain tube? At 231 is located on the left side is true...

[jetdriven]

Could be a leaky intake gasket, or the fuel injector bleeding fuel at shutdown and it runs down the rear of the cylinder to the bottom rear part. The fuel pump drain line exits at the left cowl flap.

[aaronk25]

I know that after shut down ( with mixture idle shut off) that if I try a restart 2 min later the engine is flooded.

So if the fuel does leak into cylinders after shut down how does it get out of the intake assemble as there is gaskets of which were all replaced 30 hours ago. There not cooked either as Cht haven't been over 380.

Dropping off at AP today will tell him about possible fuel draining into cylinders after shut down.

Also will check mechanical pump but I doubt that's it as its a long way from the RH side of the cowl.

Thanks all for suggestions!

[aaronk25]

 

Here are the pictures:

 

http://mooneyspace.com/gallery/image/34580-/

http://mooneyspace.com/gallery/image/34579-img-13521/

http://mooneyspace.com/gallery/image/34578-img-13481/

 

[Marauder]

Have you followed the fuel lines and see if they are all secure? Fuel divider as well...

[carusoam]

Light blue stain, dark blue stain, and dark brown stain... Signs of a lot of leakage outside where fuel is supposed to be.

That appears to be evaporating/concentrating (blue pigment) followed by a leaky seal on the intake tube. This is normal behavior for carbureted engines where the blue goo collects as a thick coating in the tubes. The seals are easy to change by your mechanic of course.

Unfortunately, you don't have a carburetor at the lower end of the tubes!

Seek professional help on this one...

Best regards,

-a-

[N201MKTurbo]

Wow, that's a lot of blue.

[carusoam]

Aaron,

Do you have a JPI?

You may have noticed a leaning effect on that cylinder, created by the air leak while running...

It is unlikely that fuel would come out at the oil return.

It is unusual that fuel would collect in the intake tubes.

It is unusual that fuel would leak out of the intake tubes.

Thoughts of a Mooney pilot.....

Not to be confused with a mechanic by any means...

Best regards,

-a-

[aaronk25]

Any chance it could be the vents on the gami nozzles seeping some fuel because I operate at full throttle at all attitudes via LOP operations and that lowers the differential pressure between MP and atmospheric?

[Marauder]

Any chance it could be the vents on the gami nozzles seeping some fuel because I operate at full throttle at all attitudes via LOP operations and that lowers the differential pressure between MP and atmospheric?

Aaron -- like Turbo said, that is a lot of blue. Doesn't look like a seep but a leak. Are you sure it is dried fuel? Ever look at the engine right after a flight and see if fuel is there? Fuel is the most likely cause of the blue, but there shouldn't be that much there.

[carusoam]

The FI nozzles don't normally allow for evaporation/concentration of the blue dye...

That requires air.

It appears that the blue is concentrated more in some spatters than in others.

Tell us when you bring it in...

Best regards,

-a-

[Marauder]

Aaron -- have you ever tried removing the cowl and turning on the boost pump? I am wondering if you don't have a leak at the injector lines, a crack in an injector or a loose injector connection. There is an SB or AD out there for inspection of the injector lines. Is your Mooney covered by this?

[DonMuncy]

You might try removing the cowl and fire up the engine. I  had a leak that did not show up without the engine fuel pump running.

[aaronk25]

Ok airplane is in dodge center at the IA/AP so we will see what he says. Thanks for the suggestions.

How do the vents work on the Injectors?

[aaronk25]

Mechanic said the fuel is coming out the vents on the injectors. I think he said the fuel diverter wasn't closing or could have been hanging up and that's how my fuel pressure was leaking out after shutdown and without the vacuum on the injectors the fuel ran out the vents down the side of the cylinder, down the intake tubes.

I've heard a noises after shut down that sound like fuel bubbles going thew a vent......

[Marauder]

Mechanic said the fuel is coming out the vents on the injectors. I think he said the fuel diverter wasn't closing or could have been hanging up and that's how my fuel pressure was leaking out after shutdown and without the vacuum on the injectors the fuel ran out the vents down the side of the cylinder, down the intake tubes. I've heard a noises after shut down that sound like fuel bubbles going thew a vent......

The hissing sound is normal. I am surprised by the amount fuel that came out of your vents. Did he say it would correct itself?

[aaronk25]

He disassembled something that is supposed to hold the fuel when mixture is cut off and noticed some marks in it and he thinks it was hanging up. He did something with it. Also prior to this fuel always leaked into cylinders after shutdown so sounds like whatever the part was it was faulty.

If the engine is off and not creating vacuum to pull fuel into cylinder but pressure leaks into injectors the fuel goes overboard though the vents, as I understand it.

[manu damaschin]

Is this problem solved?

[jetdriven]

If the fuel pressure bleeds down faster than a couple minutes its something to do with the fuel injector servo, the pressure is measured there. I saw a guy flying a Beech Sundowner, and after an hour flight he had tons of blue dye on the nose gear. I advised him to get that checked out quick, there should only be fuel coming from the sniffle valve, and sometimes out the injectors themselves after a hot shutdown. The bleed hole is under the cap on the injector. Usually only vapor comes out.

[aaronk25]

The blue staining has stopped since the previous post. Hasn't repeated.