Engine quit on takeoff roll

[carusoam]

Clarence,

Does the M20K’s engine have the electric fuel pump come on automatically or is it really not on during a normal T/O run?

Thanks for sharing your knowledge,

-a-

[Bryan]

6 hours ago, carusoam said:

Bryan, any knowledge regarding the electric fuel pump being activated during full throttle?

Best regards,

-a-

Don’t know. I will retake another look at the POH but there is definitely a checklist item to turn it off for TO. Next time I have a question to DMax, I will ask about this one.

[N231BN]

There is no throttle switch to activate the fuel pump on a M20K. That is very specific to the Ovation, many other aircraft with the same engine don't have that feature either. I'm not sure why Mooney did that, perhaps they were having vapor problems with that installation.

If you used high boost in a K on takeoff you wouldn't get very far.

[Guest]

5 hours ago, carusoam said:

Clarence,

Does the M20K’s engine have the electric fuel pump come on automatically or is it really not on during a normal T/O run?

Thanks for sharing your knowledge,

-a-

Not to my knowledge, Bravos, yes.

Clarence

[Jim F]

On lycomings they use servos and in the servo there is a diafram with incoming fuel pressure ( from the fuel pump) and out going fuel pressure( to the flow divider) and if incoming fuel pressure increased like the boost on then the fuel meatering valve will adjust the mixture to keep it from going to rich. 

On a Continental the fuel system is ground adjusted so the fuel pressure is correct for takeoff power and if you turn on low boost the fuel pressure to the nozzles will increase slightly. If you turn on high boost you will go over rich and the engine will most likely quit. On the 231/252 There is no auto function to high fuel boost. 

Most lycomings ( that I have seen) have check list to turn on the boost pump for takeoff and if the engine driven pump fails the boost pump should keep everything running. 

On Continentals we were trained that on takeoff with engine power loss you switch high boost on and lean as needed.  Very simple system.

Not to beat a dead hours but that is why the guys that know Continental engines keep saying “get your fuel flows adjusted” 

[Piloto]

On ‎5‎/‎13‎/‎2018 at 8:15 PM, 81X said:

Some more color on this issue- I performed about 12 high speed taxis.  Issue reproduced the first couple of taxis.  Third time around, the engine stayed alive but was surging from 38"mp to about 33, and it seemed to need more throttle than usual.  Fourth time around and now we're getting somewhere, I ran the high speed with the low boost on.  fuel flow seemed a little low but the surging was gone.  it seemed to almost hold 36 as per normal.  

Throughout all of this, the fuel flow seemed too low- about 18-19GPH whereas it's normally about 23 GPH at 36".  

So, I suspect it's the mechanical pump is going (or has gone) bad.  It's going in to the shop tomorrow to find out for sure, I'll report back to hopefully help someone out in the future.  

Related, who runs their M20K's with the low boost on for TO and landing?  The POH says not to, but this experience gives me pause during those critical phases of flight.  

Do you get the same symptoms with the plane still on the run up area at full power? Try switching fuel tanks to see if the problem goes away.

José

[Mooneymuscle56m]

A friend of mine installed a factory remanufactured LB on his M20K.  After 50 hours the engine it would only run on the low boost.  Thankfully under warranty.  

Everyone assumed it was the mechanical fuel pump, replaced with no change in operation.  Then the troubleshooting got deeper.  Turned out to be the fuel diverter.  

Continental stood behind their product and picked up the tab. 

 

 

[81X]

To close the loop on this, it was a compound problem.  After a consult with my mechanic and a special thanks to Don Maxwell, I ended up sending the entire fuel system out for overhaul.  The fuel pump impeller was shot and the diverter was also having issues.  Furthermore, some o-rings were broken and dried out.  It's been 14 years since factory reman and after speaking with aircraft carbs and fuel injection who OH'd it, they say it should be all but mandatory for an overhaul or at least IRAN after 10 years (of course in addition to the flammable hose replacement)

So, food for thought if it's been 10 years since your fuel injection system has been overhauled, you might want to look at that during your next annual.  

--not a mechanic, just thoughts from an owner--

[jetdriven]

WRT hosed they’re are incorrect on the 10yr recommendation. Teflon Hoses are On condition. 

[Parker_Woodruff]

On 5/13/2018 at 11:04 AM, carusoam said:

On the topic of fuel pumps...

The K has two...

• electrical
• mechanical

Both should be on for Take-off.  Depending on which engine set-up you have...  the electric pump operation may be automated.

PP thoughts only. Not a mechanic...

Best regards,

-a-

electric pump should be off for takeoff.

[Parker_Woodruff]

11 hours ago, 81X said:

To close the loop on this, it was a compound problem.  After a consult with my mechanic and a special thanks to Don Maxwell, I ended up sending the entire fuel system out for overhaul.  The fuel pump impeller was shot and the diverter was also having issues.  Furthermore, some o-rings were broken and dried out.  It's been 14 years since factory reman and after speaking with aircraft carbs and fuel injection who OH'd it, they say it should be all but mandatory for an overhaul or at least IRAN after 10 years (of course in addition to the flammable hose replacement)

So, food for thought if it's been 10 years since your fuel injection system has been overhauled, you might want to look at that during your next annual.  

--not a mechanic, just thoughts from an owner--

glad you got it handled and thanks for reporting back.

[ArtVandelay]

electric pump should be off for takeoff.

Why, I thought it was as a backup for the manual pump?

[Marcopolo]

18 minutes ago, teejayevans said:

Why, I thought it was as a backup for the manual pump?

Anthony's example above was on an M20K model, the electric pump on the K model is off for all regimes of flight where the engine driven pump is working, including take-off and landing.  It is used to provide fuel flow before/during starting and at any time that the engine driven pump fails.

 

Ron

[midlifeflyer]

Just now, Marcopolo said:

Anthony's example above was on an M20K model, the electric pump on the K model is off for all regimes of flight where the engine driven pump is working, including take-off and landing.  It is used to provide fuel flow before/during starting and at any time that the engine driven pump fails.

 

Ron

...and, keeping it that simple, it's off for takeoff because it would result in a too-rich, perhaps incombustible,  mixture

[ArtVandelay]

Anthony's example above was on an M20K model, the electric pump on the K model is off for all regimes of flight where the engine driven pump is working, including take-off and landing.  It is used to provide fuel flow before/during starting and at any time that the engine driven pump fails.

So, you watch the fuel pressure on takeoff and turn on electric backup if required?

[Marcopolo]

Just now, teejayevans said:

So, you watch the fuel pressure on takeoff and turn on electric backup if required?

Yes, per the POH.  I watch the fuel "flow", no pressure gauge, and listen very intently to the engine with a finger pointed to the switch for the electric pump in case I need it.  As Mark stated above, if you try to turn the electric pump on while the engine driven pump is operating the engine will die shortly there after due to an uncombustabley rich mixture, and we don't want that on take-off or landing.

 

Ron

[ArtVandelay]

Yes, per the POH.  I watch the fuel "flow", no pressure gauge, and listen very intently to the engine with a finger pointed to the switch for the electric pump in case I need it.  As Mark stated above, if you try to turn the electric pump on while the engine driven pump is operating the engine will die shortly there after due to an uncombustabley rich mixture, and we don't want that on take-off or landing.
 
Ron

Wow, if you have an intermittent failure, your screwed, either not enough fuel or too much.

[Marcopolo]

23 minutes ago, teejayevans said:

Wow, if you have an intermittent failure, your screwed, either not enough fuel or too much.

If that were to happen then I guess I would get really good really fast at using the red mixture knob with the electric pump on, pull it out a bit when the engine pump is working and push it in when its not!  

 

Ron

[carusoam]

Thanks Parker and Ron!

For the valuable updates and clarification.

Thanks 81X for the follow-up.

Best regards,

-a-

[81X]

Also, some more color on the 10 year FI overhaul recommendation-

The hoses are a totally separate issue and were actually replaced about a year ago.  The amount of dry rot on the o rings and diaphragms in the FI system lead to my problems.  I could also see where it could cause possible issues of fuel spraying where it's not supposed to be, having a chunk go into your diverter, etc.  

 

 

[HRM]

On 5/13/2018 at 8:39 AM, jlunseth said:

Leakage through the cap is an issue.  The cap sits in a well so that when installed it is flush with the wing surface.  Water collects in the well when it rains, just looking for a chance to get into the tank.  If one of the O-rings is bad, that’s all it takes.  

I keep a roll of this in my E. Couple of strips over each fuel cap when forced to tether outside and no worries of water incursion. Of course, cabin leaks are a different matter 

[HRM]

On 7/4/2018 at 8:24 PM, HRM said:

Couple of strips over each fuel cap when forced to tether outside and no worries of water incursion.

Meant to add that the tape is also a barrier to Linemen. During their training they are indoctrinated with respect for the color blue. I like to personally monitor the fueling process and I prefer to be the only one to touch the caps. I also like to be fueled just before leaving, the FBOs like to fuel you up right away, but if your Mooney sits on the line for a day or two you lose a lot of fuel out the expansion port!

Good tipping is just good pilot behavior--the line guys will completely ignore your fueling idiosyncrasies after a good tip.