Whats Up With My FUEL?

[RLCarter]

Been bringing a "hanger find" back to life and was doing some run-ups and taxi test when my Vacuum Pump went south. I had planned on checking the filter screen at the fuel servo after an hour of total running time but with cowl off for the vacuum pump and 40 minutes of running time I went ahead and checked it today. While removing the fuel line, fuel was dripping from the line as it loosened up but with my hand in the way and the lower cowl still on the dripping fuel looked odd. With the line removed from the fuel servo I decided I would turn on the electric pump and catch some fuel in a container just for piece of mind. Sure enough, my old eyes weren't playing tricks on me in the poor lighting. Below is what I got out of my plane today, here is what I have done in the past week prior to seeing this. Both tanks were drained (for new weight & balance) and I personally added 5 gal of 100LL right from the fuel farm (as a side note the fuel that I removed for the W&B was old but it was still blue). After adding fresh new fuel I ran the engine twice to check for leaks or issues (FWF all hoses were replaced) for approx. 20 minutes each time. Today after finding this I sumped the tanks which was nice and blue, I then pulled the fuel selector drain sampling both sides, still blue. My thought was the engine driven fuel pump was somehow allowing engine oil into the fuel side of the pump. I looked around the mechanical pump and all is dry from what I can see. I let the jar sit for 3hrs to see if it would separate or if anything would settle to the bottom, but nothing. In the photo it looks like there is something in the bottom of the jar but it is shadow of some sort, there is nothing but this apple juice looking stuff. I ran the boost pump again and the fuel came out blue shortly after turning it on, going to let it sit overnight and see what happens in the morning. You guys got any ideas or seen this before?

 

Edited July 28, 2016 by RLCarter

[Raptor05121]

No pictures

[RLCarter]

Shows on my end, will edit and attach another one

[Hank]

That just looks wrong . . . No idea what happened. Was some crud inside the pump? Did you clean the tanks while they were empty? What would be left after running the engine for 20 mins??

[RLCarter]

3 minutes ago, Hank said:

That just looks wrong . . . No idea what happened. Was some crud inside the pump? Did you clean the tanks while they were empty? What would be left after running the engine for 20 mins??

When draining the fuel last week all was good, then this today...i'm stumped, as is my IA, the morning testing might turn up something, if not I'm ground running it a getting another sample

Edited July 28, 2016 by RLCarter

[kerry]

My guess would be what your thoughts are with the mechanical fuel pump seeping oil and mixing with your fuel.  Any oil around the pump.  I would switch it out and see what happens.

[ArtVandelay]

My guess would be what your thoughts are with the mechanical fuel pump seeping oil and mixing with your fuel.  Any oil around the pump.  I would switch it out and see what happens.

If that's the case, pour it some onto a paper towel, the avgas will evaporate quickly leaving the oil behind.

[RLCarter]

3 hours ago, teejayevans said:

If that's the case, pour it some onto a paper towel, the avgas will evaporate quickly leaving the oil behind.

Tried that along with the painted floor of the hangar and several other surfaces with no joy, its just leaves a stain (not oily)

[ArtVandelay]

3 hours ago, teejayevans said: If that's the case, pour it some onto a paper towel, the avgas will evaporate quickly leaving the oil behind.

Tried that along with the painted floor of the hangar and several other surfaces with no joy, its just leaves a stain (not oily)

Then based on this and your tanks are clear, I would start disconnecting hoses starting at fuel tank side of the fuel switch and work my way till I found the brown gas.

[Marcopolo]

Does it smell like fuel...or oil?  if you were to lite a small portion of it how does it burn?  What color is the smoke?  It looks like aged auto gas to me which would smell like turpentine.  Teejay has a good troubleshooting tree started for you.  You mention replacing hoses FWF, re-check for proper routing and connecting.  Is your oil level going down as you drain this brown-ish liquid?

 

Ron

[N201MKTurbo]

So, check it along the path and see where it turns brown. Sump the tanks, get some from the fuel selector, disconnect the fuel line at the firewall and get some fuel before it goes through the mechanical fuel pump.

My thought is that there is varnish buildup somewhere in the system from years of old fuel evaporating and the new fuel is dissolving the varnish and washing it out of the system.

[RLCarter]

Ron,

Smells like 100LL, checked the oil level (no change and no smell of fuel). the quantity in the jar is about all that I got out of the system.

N201,

All is good up to the engine driven pump (nice and blue), I'm headed back to the hangar after letting it sit over night and see what I can find. It does look old car gas but after 35+ years of cleaning motorcycle carbs I am very familiar with the smell of what we called money. When I purchased the plane 2 years ago the first place I went to was the fuel tanks to see if it had auto fuel (100LL was in it). I have sumped the tanks and valve numerous times over the past 2 years of getting it ready to go back up with no issues. Tanks were drained for a New Weight & Balance last week and nothing like this was seen.

 

[carusoam]

I typed slower than the data came in....

See if I got this right....

0) you have not revived a barn find before, have you?   (It turns out you have done this before!)

1) How long has your hangar find been sitting?

2) Is it's previous owner not available for questions?

3) You ran the engine for a significant period of time?

4) you drained a large volume of fluid from the fuel system and you want to know what it is...

5) it had no blue coloring, so it's not 100LL.  The fuel can evaporate leaving blue behind.  Blue doesn't normally leave on its own.

6) when you ran the engine, it didn't blow tremendous amounts of smoke out the exhaust. So it's not oil.

7) It ran burning this stuff, so it's not water.

8) If you could ask one question to the previous owner... Ask if he used one tank for T/O and the other for cruise only?

9) when you put s drop of this stuff between your fingers and rub.  Viscosity thin like water, or thick and slippery like oil?

10) that is a large jar of fuel that you have drained.  It would have been better to have drained both tanks empty, which is difficult because a few gallons try to stay behind.

11) It looks like the previous owner may have used 100LL in one tank and Mogas in the other...?  A classic cost saving mechanism used on other planes.  Not done with Mooneys because of rubber seals,  bits and pieces not compatible with Mogas.

12) if you follow any advice of lighting things on fire.  Do it safely, outdoors, only a drip is needed. Fire extinguisher ready to go.  Don't turn your project into flaming wreckage...

Hope this helps your logic path.

Best regards,

-a-

[N601RX]

You mentioned that all the hoses had just been replaced. When building up a hose it is common practice to lube the ID of the hose and the nipple that screws up into it with heavy oil.  

[RLCarter]

All hoses were lubed well, but then flushed afterwards. This morning some of the 100LL had evaporated leaving an oily residue behind on the glass. Fuel Pump (engine driven) is coming off and I'll pressurize the fuel side on the bench and see if I get fuel on the oil side while on the bench. More details to follow, daily certain the pump has failed 

[RLCarter]

Driven pump was removed then plumbed back into the fuel system. With the boost pump on there was signs of fuel leaking anywhere, still stumped but still convinced that the mechanical pump has an issue so a NEW (not overhauled) pump was ordered. Will run the same test once the new one is installed.

[Yetti]

I believe the hard lines are alum... but if they were steel, it could be rust.   Also could be the plastic parts in the dukes pump. Did you clean/redo the filter on the downstream side of the fuel pump?

 

[mike20papa]

If it's this black residue when the fuel evaporates..I would suspect the rubber diaphragm is decomposing due to either age or exposure to mogas.  My lawn mower engines will exhibit something similar..after hours & hours of operation, the clear plastic fuel filters turn black.  I suspect it is from long term effects of minimal amounts of alcohol in mogas working on the fuel lines.  You said this crap came out of the fuel system after running the aux. fuel pump, right?  Did you sample the fuel before or after it ran thru the engine driven pump? 

[RLCarter]

42 minutes ago, mike20papa said:

If it's this black residue when the fuel evaporates..I would suspect the rubber diaphragm is decomposing due to either age or exposure to mogas.  My lawn mower engines will exhibit something similar..after hours & hours of operation, the clear plastic fuel filters turn black.  I suspect it is from long term effects of minimal amounts of alcohol in mogas working on the fuel lines.  You said this crap came out of the fuel system after running the aux. fuel pump, right?  Did you sample the fuel before or after it ran thru the engine driven pump? 

Tanks were drained at the fuel servo hose last week to get a current empty weight & CG, new fuel was added afterwords. New fuel was added, sumped both tanks and the fuel valve, test ran & taxied for 20 minutes, the following day did the same thing but the vacuum pump was weak on startup and failed completely with in 5 minutes of running, I taxied around and did a run up for a total of another 20 minutes. After replacing the vacuum pump while the cowl was off I checked the finger screen in the fuel servo (same line I used to drain the tanks) and noticed the golden color fuel.

[RLCarter]

As a side note, the aircraft has been going through a very extensive annual, the same servo line has been used multiple times for fuel samples. Injectors and fuel flow was also checked, the golden color fuel was only found after the engine was ran. There is a Service Bulletin for faulty engine driven pumps (mine wasn't affected). The mechanical pumps are a modified AC Delco with an added chamber to keep the engine oil & fuel seperated from each other, the center camber has a vent line that goes out the bottom of the cowl. There was no signs of a fuel or oil leaks on the exterior of the pump, but that is the only place the engine oil & fuel could come in contact with each other.

[carusoam]

Another thing chemical engineers do when comparing the color of fluids...

1) get two identical glass containers.  Nessler tubes 

2) fill them to identical heights.

3) put them in front of a white background.

4) observe from the front, or top...

5) compare to a couple of standards.  A cup of 100LL and a cup of your current oil.

6) compare to whatever drains out of the oil pan as well.

https://en.m.wikipedia.org/wiki/Nessler_cylinder

7) if you only have a drip to compare to, use a white paper towel with identical drips.  See how the drips spread, what their color is...

I am only a PP, not a mechanic.

Best regards,

-a-

[RLCarter]

New mechanical fuel pump corrected the issue on the fuel color. While looking into the issue I removed the gascolator bowl again just as a precaution so I ordered a new gasket (2.00" x 1/6") from Brown Aircraft. Got it all assembled and now there is a fuel leak at the gascolator bowl and fuel valve mating surfaces (new gasket or old gasket), Both mating surfaces are clean and with no signs of any damage not even a scratch on the surfaces.. I have searched MS and found where they are leaking from the valve body and are sent off for OH. The valve works very smooth and all detents are positive, I have not taken the valve off the aircraft as its a sealing surface leaking so an overhaul shouldn't be needed. Any ideas?

[Yetti]

There is an SB for torque values.  Some were marked with higher values then you wanted to go and broke the assembly.   Where is it leaking.  You should have used a new washer for the bolt.  It is a fancy oring on a washer, not just a washer.  The screen might be slipping over to where it should not be.

[RLCarter]

1 minute ago, Yetti said:

There is an SB for torque values.  Some were marked with higher values then you wanted to go and broke the assembly.   Where is it leaking.  You should have used a new washer for the bolt.  It is a fancy oring on a washer, not just a washer.  The screen might be slipping over to where it should not be.

You wouldn't happen to know the SB#? A new stat-o-seal (fancy o-ringed washer) was used, screen fits snugly. I'm also going on the assumption that the assemble order was correct when it was taken apart, screen over the center of valve body, gasket then the bowl, stat-o-seal washer and bolt? I've had it apart twice with no issues before yesterday. 

[Yetti]

m20-200

I would have to look at the manual for the order