how to start without an electric fuel pump

[bdavis3223]

My annual is scheduled for next month for my M20F. Over the weekend, my electric fuel pump quit working. How do I need to change my startup procedure until I can get it fixed?

[ArtVandelay]

I would rethink flying without a backup fuel pump.

[PT20J]

The boost pump is listed as required equipment in the TCDS, so flying without it would be a violation of FAR 91.9. But, if you just want to ground run it, you could spray some starting fluid in the intake manifold. 

[N201MKTurbo]

You will get fuel pressure just cranking it. I rarely use the boost pump to start my plane.

If you need to fly it somewhere for maintenance, you will need a ferry permit to do it legally.

[kortopates]

Here is an opportunity to exercise your superior aeronautical decision making rather than rely on superior airmanship if your engine driven fuel pump also develops an issue and ground your bird till you can get your boost pump replaced or repaired.


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[TaildraggerPilot]

Bad idea. Very bad. 

[bdavis3223]

Great feedback, everyone! I appreciate it, thank you.

[Utah20Gflyer]

Aero motors could likely have a replacement to you in less than a week, they are probably half the cost of a new one and build in improvements the original fuel pump lacked.  Give them a call!  

[varlajo]

If the idea is to run the engine on the ground, start cranking with mixture at idle cut off and slowly advance mixture while continuing to crank. Be patient. 

I wouldn't fly with an INOP boost pump. 

[Joshua Blackh4t]

Someone I know was in this exact state a while ago in an M20E.

It took a few months to get a new pump so he was flying it around without an issue. 

To start cold it, it takes a bit more battery. 

Full rich, cracked throttle and then crank. It takes a few turns to build fuel pressure, then 5 seconds later it should start. 

You might have to crank to pressure, rest the starter, then start it. 

 

While you are at it, make sure you change your post to have it on record that the pump is still working and you are only asking for information. 

Mechanical pumps rarely fail, and many people have electric backup pumps that are not rated for continuous duty and probably won't get them very far, so I don't see much increased risk.

Information for ground starting purposes only :p

 

 

[Jim Peace]

5 hours ago, Joshua Blackh4t said:

Someone I know was in this exact state a while ago in an M20E.

It took a few months to get a new pump so he was flying it around without an issue. 

WTF.....

[kortopates]

WTF.....

Normalization of Deviance!


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[varlajo]

39 minutes ago, kortopates said:

Normalization of Deviance!

I mean.. These things fly perfectly straight without alternators, seat belts, airspeed indicators, transponders, or airworthiness certificates.. 

[AndreiC]

Taking out the pump is not difficult. Takes about an hour, it is under the pilot legs, just behind the cowling. I had mine sent to Aero Motors and they had it back to me in under a week. I installed it back under the watchful eyes of an A&P/IA who was kind enough to come to my airport and look at the work and sign it off. (We don't have a regular mechanic at my field.) Whole thing was a non-issue.

[Fritz1]

got a replacement boost pump last year from Aircraft Accessories of Oklahoma overnight, they have done a lot of work for my plane over the years, reliable and responsive

[Joshua Blackh4t]

On the note of fuel pumps:

I know most handbooks say to use the boost pump on take off and landing, but I used to fly an ultralight that made me challenge that assumption. 

The ultralight had gravity feed, and a mechanical pump, and also an electric pump. The electric one was good for priming but it could flood the carburetor, especially if taxiing on bumpy ground. 

So it made me think: we start our engines, warm up and run-ups all without the fuel pump. So that, to me, is a known safe state. So then, just before takeoff we turn it back on? To a state we haven't tested? 

Even worse on landing. Whats more likely: a plane that ran for 3 hours will continue to do so for 5 minutes, or that the electric fuel pump will have a catastrophic failure when switched on? Its just been vibrating for 3 hours after all. 

I'm all for people doing what they consider is safe, but personally I use the electric pump very little although I have memorised its switch and can get there very quickly at the first sign of trouble. 

Have also never needed it when changing tanks. 

Although I do need it on a hot day 3 seconds after start to clear out vapour in the fuel lines. 

 

Anyway, everyone makes their own risk calculation. I've always had a rule that you are allowed one sub-optimal thing at a time. Weather/night/tired/annoying passengers/minor mechanical issue. NEVER fly (or drive, etc) with more than one.

[Pinecone]

The reason for taking off and landing with the boost pump On is so that if the mechanical pump fails, the engine continues to run.

Another possible failure is where the line from the tank to the engine driven fuel pump start leaking.  The pump will draw air and not fuel.  The boost pump is down low and is gravity feed.  The engine fuel pump is up higher and has to suck the fuel up to it.  Many high wing aircraft don't even have an electric fuel pump.

If you UL was gravity feed, it most likely had a carburetor, which does not require the higher fuel pressure that fuel injection does.
 

 

[Hank]

2 minutes ago, Pinecone said:

If you UL was gravity feed, it most likely had a carburetor, which does not require the higher fuel pressure that fuel injection does.

Yep. My C flies great on 2 psi; the green arc is 0.5 to 4, while typical fuel injected pressure is > 30 psi.

Other than cold starts, I rarely use my electric fuel pump. Same for carb heat, flip on after start, check for drop, turn off. Then again, it's ready whenever the Carb Temp gage gets in the orange stripe, usually only a concern inside some clouds.

[EricJ]

5 hours ago, Joshua Blackh4t said:

So it made me think: we start our engines, warm up and run-ups all without the fuel pump. So that, to me, is a known safe state. So then, just before takeoff we turn it back on? To a state we haven't tested? 

Even worse on landing. Whats more likely: a plane that ran for 3 hours will continue to do so for 5 minutes, or that the electric fuel pump will have a catastrophic failure when switched on? Its just been vibrating for 3 hours after all. 

+1 that the electric pump is the backup during takeoff and landing in case the mechanical pump fails.   When you're at cruise altitude you'll have time to troubleshoot, but near the ground you can't count on having, and likely won't have, time to deal with sorting out what happened and turning on the electric pump.   At least, I'm not gonna count on that.

Another utility of the electric pump is that if the mechanical pump gets overheated for whatever reason it can boil the fuel and cavitate during it's suction draw stroke.   The electric pump will pressurise the input to the mechanical pump and make this much less likely, or mitigate it if it happens.   I have to use the electric pump during hot starts at high DA for this reason.

The mechanical pump and the electric pump are designed to be reasonably fail-safe with each other.  In other words, the diaphragm-type mechanical fuel pump in many Mooneys will allow fuel to flow through it if it fails if there is pressure from the electric pump.    Likewise if the electric pump fails (or isn't turned on), the mechanical pump can still draw fuel through it.   These common failure modes are all tested and have to be demonstrated during certification, so they're all tested, safe states. 

Also, the fuel servo is essentially an output fuel pressure regulator, and it is largely insensitive to input fuel pressure as long it is high enough to allow regulation of the required output pressure.   Increasing the input pressure doesn't really bother it, which is why you can turn the electric pump on or off and not see a change in engine output parameters.   It's extremely difficult to overpressure the input of the fuel servo, so that's nothing to worry about.

[N201MKTurbo]

The last time I paid someone to do a complete annual on my plane, I took off on the post annual test flight. When I got to altitude, I turned off the boost pump and the engine quit. I turned it back on and returned to the airport. The fuel line from the firewall to the fuel pump was about to fall off.

That was the only time in 5400 Mooney hours that I actually needed it to keep the engine running.

[varlajo]

6 minutes ago, N201MKTurbo said:

When I got to altitude, I turned off the boost pump and the engine quit. 

Out of curiosity, do you keep the boost pump on at all times from engine start to level off, including taxi and runup? 

[Joshua Blackh4t]

I get it.

Take off is nose high and max fuel flow so it can benefit from all the help it can get so add the fuel pump especially on a fuel injected engine. Also close to the ground. 

However, as much as pumps should fail safely, pressure should be regulated all that sort of thing, we are still going from a known working state (no boost) to a new state (boosted) right at a critical stage. 

I understand that most people and most manuals will work on the principle that needing a fuel boost is more likely than the boost causing an issue, but I'm just pointing out that it could also be the other way around. 

Also, if you don't use it, you don't forget to turn it off. 

Mind you, it still needs testing before every flight, and the pilot should be very aware of where the switch is as the slightest hiccup. 

I have had an efato and did remember to try it but didn't help. 

[N201MKTurbo]

44 minutes ago, varlajo said:

Out of curiosity, do you keep the boost pump on at all times from engine start to level off, including taxi and runup? 

No, I turn it on during run up and turn it off at about pattern altitude. In this case, the mechanical pump was pumping enough fuel to start and taxi, but not enough to make full power. The mechanical pump was sucking air without the boost pump running. I believe I was pumping a bunch of fuel overboard with the electric pump running. But it got me back to the airport.

[N201MKTurbo]

53 minutes ago, Joshua Blackh4t said:

I get it.

Take off is nose high and max fuel flow so it can benefit from all the help it can get so add the fuel pump especially on a fuel injected engine. Also close to the ground. 

However, as much as pumps should fail safely, pressure should be regulated all that sort of thing, we are still going from a known working state (no boost) to a new state (boosted) right at a critical stage. 

I understand that most people and most manuals will work on the principle that needing a fuel boost is more likely than the boost causing an issue, but I'm just pointing out that it could also be the other way around. 

Also, if you don't use it, you don't forget to turn it off. 

Mind you, it still needs testing before every flight, and the pilot should be very aware of where the switch is as the slightest hiccup. 

I have had an efato and did remember to try it but didn't help. 

You know that takeoff is the most dangerous phase of the flight. That is when you want all your backup systems on line. It is way more important to have it running on takeoff than landing. If the engine quits on landing, you have extra energy and you are pointed at an airport. On takeoff you have no extra energy and you are pointed away from the airport.

[ArtVandelay]

Also, if you don't use it, you don't forget to turn it off. 

I added a blue light on the instrument panel to let me know the fuel pump is on.