Todays engine driven fuel pump failure!!!

[pkofman]

4 hours ago, co2bruce said:

We have an 1999 Eagle and recently while trying to get the low fuel flow set noticed fuel leaking out of the pump underneath the plane. I'm told these fuel pumps ( on the IO 550) tend to leak out of the seals when they go bad. It was rebuilt and is fine now. I don't know if it was intentional by Continental but the pump mounts low on the back of the engine right in the middle. So when it leaked it would drop down into the belly, between the exhausts and out. Seems like the best you can hope for and least chance of ignition. Still a very scary sight, glad we were on the ground when spotted!

agreed and thank you!

[co2bruce]

i agree to always check fuel flow on takeoff roll, and rpm, but I don't think a leak at the pump would show up.

[pkofman]

39 minutes ago, co2bruce said:

i agree to always check fuel flow on takeoff roll, and rpm, but I don't think a leak at the pump would show up.

I think you are good to check but i do not think that you would notice the leak even with a fuel totalizer . I am curious as to how one could determine such a situation

One thing i forgot to mention in all of this is that i have a edm 700 and it looked completely normal.

i suppose the change in the mags and the fact with the boost off the fuel pressure was low could have been clues had i know the plane much better than i do at this point

 

[carusoam]

Tom and PK,

You both bring up a good point...  I have to review my plumbing drawings... 

Placement of the FF sensor is the important point.  Because the leak can be before or after the FF sensor... often the FF sensor is mounted on the front side of the firewall.

probably after the electric pump, but (maybe) before the mechanical pump(?).

Asside from the fire hazard, it is good to know about the leak prior to running out of fuel.  

A large leak is going to show up on the fuel gauges.   With that much missing it may show up on the nose (aroma, not cowl) as well. Hence the added value of a more precise fuel level sensor than the standard Mooney issued ones...

Fuzzy PP memories only...

Best regards,

-a-

Edited June 10, 2017 by carusoam

[Yooper Rocketman]

1 hour ago, carusoam said:

 A large leak is going to show up on the fuel gauges.   With that much missing it may show up on the nose as well. Hence the added value of a more precise fuel level sensor than the standard Mooney issued ones...

I have that more precise fuel tank gauges on the Lancair.  They are incredibly more reliable and accurate!  EXPERIMENTAL though.

Tom

[Ragsf15e]

Real sorry to resurrect this, but I think my engine driven pump is starting to leak oil out the drain nipple.  Drips right down onto the nose truss and then left side of nose gear (68 F).  

What shops are people using to get these rebuilt these days?  Is that generally the solution for them leaking oil?

[Shadrach]

On 6/10/2017 at 9:28 AM, Yooper Rocketman said:

I believe all fuel flow transducers are AFTER your fuel pumps, just before your fuel distribution mechanism (carb'ed or injected).  A fuel leak before the transducer will not be evident in the FF instrument.

Tom

Well now it depends on the size of the leak doesn't it?   Indeed you are correct about the transducer mounting.  Most of the ones I have seen are mounted in the line that goes from pump to servo/carb.

Edited June 12, 2019 by Shadrach

[Shadrach]

47 minutes ago, Ragsf15e said:

Real sorry to resurrect this, but I think my engine driven pump is starting to leak oil out the drain nipple.  Drips right down onto the nose truss and then left side of nose gear (68 F).  

What shops are people using to get these rebuilt these days?  Is that generally the solution for them leaking oil?

Fuel pumps should definitely not leak oil, Are you sure it's oil and are you sure it's the fuel pump drain.  Does your pump have a cover over it?

[Ragsf15e]

12 minutes ago, Shadrach said:

Fuel pumps should definitely not leak oil, Are you sure it's oil and are you sure it's the fuel pump drain.  Does your pump have a cover over it?

It’s the small tube coming from the mechanical, engine driven pump. I guess I was under the impression they were driven with some type of oil pressure system, no?  I thought I read they have multiple seals inside on the fuel side and oil side to keep the two fluids separate?

Not sure what you mean by cover.  Its the small pump attached on the lower pilot side of the back of the engine.  No cover I can see.

Edited June 12, 2019 by Ragsf15e

[Shadrach]

2 hours ago, Ragsf15e said:

It’s the small tube coming from the mechanical, engine driven pump. I guess I was under the impression they were driven with some type of oil pressure system, no?  I thought I read they have multiple seals inside on the fuel side and oil side to keep the two fluids separate?

My smartass humor is lost on most... So the pump can leak oil at case flange. The drain tube should be attached to the housing on the pump. (see image). They typically leak fuel when the pump starts to fail.  Perhaps it's common for the pumps to get oil fouled but I've not seen that.

Edited June 13, 2019 by Shadrach

[David Lloyd]

Lycoming mechanical fuel pumps as pictured have two diaphrams one sealing the engine oil, the other fuel, with the space between connected to a drain.  If the upper leaks, engine oil comes out the drain.  Other, fuel.  Either way the pump continues to do it's job.  Let it go and have the other fail and bad, sad things will happen.  Continental engines have a completely different arrangement.

[carusoam]

Guess we now know which of the two diaphragms needs to be replaced...

But, both will be swapped out with the OH...

Mechanical pumps don’t seem to fail very often compared to the electric ones...

PP thoughts only, not a mechanic...

Best regards,

-a-

[Ragsf15e]

20 hours ago, Shadrach said:

My smartass humor is lost on most... So the pump can leak oil at case flange. The drain tube should be attached to the housing on the pump. (see image). They typically leak fuel when the pump starts to fail.  Perhaps it's common for the pumps to get oil fouled but I've not seen that.

Dang, usually I’m pretty good picking up the dry/smartass humor too, sorry!

Thanks for the help guys.  Makes sense and I’ll have my mechanic take a look at it.  

Are there any preferred shops to have these rebuilt?

Thanks!

[Yetti]

Buy a new one.   The price difference between a rebuilt and new is $50 or so.   There is not really a way for oil to get into the place that would drain into  the tube.    Are you sure it is not the oil breather tube?   Or oil is around the engine compartment and landing on the pump drain line?

Do a leak down test on your mechanical pump.

Start sequence. of pump on for 6 seconds with mixture open.    Close mixture then pump off.    Watch your Fuel Pressure.   Should stay charged for a minute or so with a slow leak down.   Fast leak down means your pump is bad.

 

[Ragsf15e]

2 hours ago, Yetti said:

Buy a new one.   The price difference between a rebuilt and new is $50 or so.   There is not really a way for oil to get into the place that would drain into  the tube.    Are you sure it is not the oil breather tube?   Or oil is around the engine compartment and landing on the pump drain line?

Do a leak down test on your mechanical pump.

Start sequence. of pump on for 6 seconds with mixture open.    Close mixture then pump off.    Watch your Fuel Pressure.   Should stay charged for a minute or so with a slow leak down.   Fast leak down means your pump is bad.

 

I’ll try that this weekend, thanks.  Think it would still hold pressure with a leak on the oil side though?

[Yetti]

There is no "oil side" to the mechanical pump on your F.

There is a pin runs off the cam that pushes on a lever that makes the diaphragms pump fuel

While the pin is oil lubricated, it is not under direct oil pressure.   There is a paper gasket that sits between the engine and the fuel pump.   That could leak if installed wrong.  But then the oil would be down back of the engine.

[Yetti]

Oh and there should be a third tube there.   drain for the sniffle valve.  Search maxwell sniffle valve.    If you have oil coming from the sniffle valve that might be a thing.   More than likely oil is coming down the outside of the tube, not inside.