63 M20C getting really difficult to start

[ragedracer1977]

  On 11/13/2017 at 1:45 AM, carusoam said:

Seeing the fuel pressure disappear so quickly...

And it not leaking out anywhere...

I get the feeling, there may be a lot of fuel going to the engine that is not being accounted for...

 

up for trying something different?

Turn on the ignition before turning on the fuel pump...

 

It is possible that the engine is getting flooded by dumping what is about ten pumps + of the throttle to the engine...

An ordinary engine mechanic with knowledge of our carbs should be able to make the proper adjustment or fix the seal that must be leaking... 

Would definitely want to know what is not working before flying it, as it could get worse...

 

PP thoughts only, not a mechanic..

Best regards,

-a-

 

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Except there's no fuel in the cylinder.  I pulled all the plugs.  They cylinders are dry.  I pulled the air filter and looked in the airbox.  The fuel should fall into it if the float bowl is overfilling.  It's dry. 

From reading on the pump, I think I might have an idea.  With the change in sound, I wonder if the motor is getting weak or the vanes worn.  It may be that with the lines disconnected, it has good flow but the pressure is lacking if that makes sense.  Also, in researching on the net I found a vehicle forum (these same pumps were used in Fords and other vehicles) where a mechanic stated that it should start out pumping fast then slow to a pump every now and then to maintain pressure.  When they fail, they continuously pump to attempt to maintain pressure.  This is because one of the failure modes is that when it fails, the fuel can flow backwards.  Which would explain why my pressure drops so quickly.  The pressure built is just equalizing with the fuel tank.  

[N201MKTurbo]

Lets think about what keeps the fuel pressure in the system. The fuel has to get stuck between immovable objects. One immovable object is the float valve in the carb. If it was leaking there would be extra fuel somewhere. Brice says there is no extra fuel so it isn't that. Then the fuel must be back flowing through the fuel pump. Normally the fuel flows from the tank to the fuel selector (may have integral gascolator) to the electric fuel pump to the mechanical fuel pump  and on to the carb.  I looked at all the manuals I had and that is how they are all plumbed. Brice says his is different and the way he described the two fuel pumps are in parallel. If this is the case then one of the fuel pumps must have a bad one way valve to allow the fuel pressure to backfeed to the tank. Otherwise there would be fuel leaking from somewhere.

 

[ragedracer1977]

It appears that parallel fuel plumbing was 'standard' from 62-64.  I did just find another post (from 2011) here where a guy was experiencing similar problems and it ended up being a hole in the line from the gascolator to the mechanical fuel pump.  However, he also posted a troubleshooting guide that says the problem is otherwise a perforated diaphragm in the pump or a bad bowl needle valve in the carb. 

From reading, the only difference I can see from what I'm experiencing and the experience in the other thread is that the pressure would fall off even with the mechanical pump going.  It seems to me that my mechanical pump is fine.  Which is, I think, why it starts after cranking so long, the mechanical pump is finally able to push enough fuel.  

So, I have a couple things to look at. I'm fairly confident at this point that like Rich says, there's a bad one-way valve somewhere or the diaphragm in the pump is perforated.  The fuel HAS to be going somewhere and if it's not into the cylinders or on to the ground, it has to be going back in the tanks.  I'm really leaning towards the electric pump since the engine runs perfect on the mechanical.

[carusoam]

I'm not familiar with the parallel pump set up...

but, I know what it’s like to have the diaphragm leak on an electric pump...

It pees fuel on the ground while you are sitting in the cabin, getting ready to start.

You might get lucky, somebody will point it out to you.

It is easy to check the pump's drains. The mechanical one has one close to the engine.  The electric one is further back.

They may be threaded nipples mounted in a round hole to allow fuel to escape.

Now you know you might have a leak... pressurize the system, get out and look for a puddle.... 

If nothing comes out, and there’s isn't any blue stains, the leak is internal...

Got any pictures of where the check valve is on your electric fuel pump? It might be a one hour, remove, clean and put back kind of thing...?

You might be ready for a fuel pump OH if it is the worst option.  Might check to see which brand and model you have in case you need to know... then look up the latest and greatest brand / model if you want an upgrade...  see if changing over to the serial in place of parallel set up makes sense...

PP thoughts only, not a mechanic...

Best regards,

-a-

[ragedracer1977]

The electric fuel pump was the issue.  $74 at Aircraft Spruce and I have a brand new pump!  My plane has the Bendix/Facet 476807.  THANK YOU MOONEY for not cursing me with a Duke's LOL!  The old pump (which was very very old, maybe original as I don't recall seeing anything in the log books about it ever being replaced) had indeed failed internally.  There is a check valve inside of it that is supposed to stop fuel flowing backwards.  It was full of gunk.  In fact, when I pulled the cover off to check the fuel screen, the inlet had quite a bit of rust in it.  From the pump itself.  The internals of the pump were corroding.  50 years of water occasionally getting in there I guess.  

Plane starts right up again!

[Hank]

Congrats! Does it hold fuel pressure now when you turn the pump off???

[carusoam]

The awesome power of MS!  

You learn about your plane, while others learn about theirs.

Best regards,

-a-

[yvesg]

  On 11/16/2017 at 1:48 AM, ragedracer1977 said:

The electric fuel pump was the issue.  $74 at Aircraft Spruce and I have a brand new pump!  My plane has the Bendix/Facet 476807.  THANK YOU MOONEY for not cursing me with a Duke's LOL!  The old pump (which was very very old, maybe original as I don't recall seeing anything in the log books about it ever being replaced) had indeed failed internally.  There is a check valve inside of it that is supposed to stop fuel flowing backwards.  It was full of gunk.  In fact, when I pulled the cover off to check the fuel screen, the inlet had quite a bit of rust in it.  From the pump itself.  The internals of the pump were corroding.  50 years of water occasionally getting in there I guess.  

Plane starts right up again!

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That price seems very low for a fuel pump. Are you sure it is certified and approved for the Mooney?

Yves

[ragedracer1977]

  On 11/16/2017 at 2:16 AM, yvesg said:

That price seems very low for a fuel pump. Are you sure it is certified and approved for the Mooney?

Yves

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Yes.  It's the proper part.  Per the TCDS for the M20C:  "(b) One, electric Bendix, 476087 (or alternate) Facet"

[neilpilot]

  On 11/16/2017 at 2:20 AM, ragedracer1977 said:

Yes.  It's the proper part.  Per the TCDS for the M20C:  "(b) One, electric Bendix, 476087 (or alternate) Facet"

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Can't find a fuel punp on Aircraft Spruce listed under 476087.  They do list a Facet 476087E, their part #05-10832.

However, in their Q&A section they indicate "Are these pumps FAA/PMA approved? No, these pumps are intended for experimental aircraft use only.".  Is this the pump you purchased?

[ragedracer1977]

  On 11/16/2017 at 2:44 AM, neilpilot said:

Can't find a fuel punp on Aircraft Spruce listed under 476087.  They do list a Facet 476087E, their part #05-10832.

However, in their Q&A section they indicate "Are these pumps FAA/PMA approved? No, these pumps are intended for experimental aircraft use only.".  Is this the pump you purchased?

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I'll have to ask the A&P.  

[yvesg]

And BTW Brice, I am not trying to point fingers at you. I am asking because I had a similar issue starting my M20C in September which led me to borrow my best friend’s Mooney (Ned) for a planned trip ... and one of the potential culprit was the fuel pump for which I checked the  replacement/overhaul options. If this Facet pump is OK you will become my hero!

After the mechanic cleaned and put the carb back together all went fine so I am expecting to replace that pump at some point...

Yves

[ragedracer1977]

  On 11/16/2017 at 2:44 AM, neilpilot said:

Can't find a fuel punp on Aircraft Spruce listed under 476087.  They do list a Facet 476087E, their part #05-10832.

However, in their Q&A section they indicate "Are these pumps FAA/PMA approved? No, these pumps are intended for experimental aircraft use only.".  Is this the pump you purchased?

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Until I can find out for sure, I wonder if it's covered under the "(or alternate)" in the TCDS.  Also, curious, when my plane was built, PMA did not exist.  It was CAR 1.55.  In fact, in all of the planes with that pump, every single one was built before PMA existed.  So, how would you ever replace a part, even with NOS, if there was no such thing as PMA for the part and never will be?

[ragedracer1977]

  On 11/16/2017 at 3:37 AM, yvesg said:

And BTW Brice, I am not trying to point fingers at you. I am asking because I had a similar issue starting my M20C in September which led me to borrow my best friend’s Mooney Ned for a planned trip ... and one of the potential culprit was the fuel pump for which I checked the  replacement/overhaul options. If this Facet pump is OK you will become my hero!

Yves

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Yours is a 1965, right?  In that case, you probably have the Dukes pump.  

[ragedracer1977]

  On 11/16/2017 at 2:10 AM, Hank said:

Congrats! Does it hold fuel pressure now when you turn the pump off???

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No, but the pressure falls much much slower.  Given how the system is plumbed, I'm not sure that it's possible to hold pressure with no leakdown.  I'll have to grab pictures.  It's hard to describe.  There's several "T"'s between the tank selector and carburetor.  

[neilpilot]

  On 11/16/2017 at 2:51 AM, ragedracer1977 said:

I'll have to ask the A&P.  

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So what did the A&P say about installing Facet 476087E (part #05-10832) in a certified aircraft?

[ragedracer1977]

  On 11/21/2017 at 4:40 PM, neilpilot said:

So what did the A&P say about installing Facet 476087E (part #05-10832) in a certified aircraft?

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The part procured was not 476087E, it was 476087.  I'm not sure where the idea that it was an E came from exactly.  He had no problem signing off on it as is, however, we did end up procuring a different pump from Mooney.  Which, believe it or not, is exactly the same pump - same box, same part numbers, same instructions in the box - everything.  They probably ordered it from Aircraft Spruce and then sent it to me.  Better to be 'correct' I guess.  It's only $115 from Mooney.

[par]

I may need to do the same thing this annual. My pump also will build pressure as yours does but then drops off immediately as the pump is switched off. I see absolutely no pressure fluctuations when the throttle is pumped. I suppose at $114 bucks, it’s worth replacing and checking.

[DXB]

It's disconcerting to find out that C models just a few years older than mine have boost pumps that last 50 years and cost 1/10 as much 

[Mooneymite]

  On 11/25/2017 at 6:04 AM, DXB said:

It's disconcerting to find out that C models just a few years older than mine have boost pumps that last 50 years and cost 1/10 as much 

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Progress?

The electric fuel pump in one of my experimentals was $8 at Autozone.  It never failed.

[Guest]

  On 11/25/2017 at 6:04 AM, DXB said:

It's disconcerting to find out that C models just a few years older than mine have boost pumps that last 50 years and cost 1/10 as much 

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Dukes are mighty proud of their products!

Clarence

[Mooneymite]

  On 11/25/2017 at 11:11 PM, M20Doc said:

Dukes are mighty proud of their products!

Clarence

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One might say "unreasonably proud".

[par]

Looking at these prices, I can't believe my eyes. I feel like I should offer to pay them more because its going on an airplane.

 

[Badmoonraising]

This is an interesting topic for me because my 64 E is also difficult to start at times. I haven't read all the posts here yet but will. I have jumped ahead to comment because earlier on someone questioned if the gascolator leaked (Raptor). Interesting because my annual just revealed that my gascolator indeed was leaking like crazy. I have yet to fire the old girl up but I'm hoping thats it!

This thread is also questioning the SOS. Sees logical to me. 

[DXB]

  On 12/12/2017 at 12:27 AM, par said:

 

 

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That's the cost of an iridium spark plug. I'd consider replacing every 5 years as preventive maintenance.  But I'm guessing there's no basis from a regulatory perspective for putting one on my '68C when my Dukes pump goes bad.  I suspect the fuel systems are basically identical otherwise? I wonder why the type of pump was changed.