After a 2 minute taxi for fuel, my F wouldn’t start

[gwav8or]

The fuel truck at my airport is down for maintenance. So today I went out to get fuel for a flight tomorrow.

 

Fuel farm is about a 2 minute taxi from my hangar.

 

Got fuel, went to use the facilities and went back to the plane.

 

Tried a normal start. Prime for 3 seconds with fuel pump. No start.

 

Tried a hot start. Full throttle, mixture all the way lean. Crank while slowly retarding throttle. Still no start.

 

Tried intentionally flooding with about 6 seconds prime with fuel pump. Hot start. Still no start.

 

It’s been hard to start in the past after a 2 minute taxi for fuel but not like this.

 

Had the line guy give me a tow back to the hangar and there was a noticeable fuel drip. So I assume jt was flooded.

 

What could be the problem? Is it just a dumb operator? Could it be a shower of sparks issue? Magnetos? Plugs?

 

 

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[MikeOH]

Well, not to be critical but I would NOT have primed after the fuel stop shutdown.

If the engine has just been running, I always leave the throttle where it was at shutdown, start cranking, and slowly bring in the mixture.

[gwav8or]

Well, not to be critical but I would NOT have primed after the fuel stop shutdown.
If the engine has just been running, I always leave the throttle where it was at shutdown, start cranking, and slowly bring in the mixture.

Yeah I agree with you. I just didn’t think it would be hot enough to cause starting issues after running for such a short time.


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[MikeOH]

8 minutes ago, gwav8or said:

Yeah I agree with you. I just didn’t think it would be hot enough to cause starting issues after running for such a short time.


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I think it's more that fuel is still present so priming isn't needed, and doing so runs the risk of flooding.  I went to the pumps this morning, which are about 2 mins from my hangar, shutdown, fueled, and restarted.  My engine wasn't warm at all at that point, but started right up with no prime.

[PT20J]

Kind of sounds flooded, and if you usually prime after a short taxi and it has been reluctant to start I would try not priming in the future. All your attempts may have flooded it more and then it takes a lot of cranking with the mixture in ICO and the throttle wide open to get it lean enough to fire. You can determine if it's really flooded badly by getting out and checking to see if fuel is draining out the sniffle.

[Ron McBride]

I would taxi all the time very lean.   Shut down at 1100 rpm.   When ready to restart, do not move the throttle, prop or mixture.  Do not turn on the fuel pump.   Crank engine and advance the mixture slo.  W.  Ly.  It should start quickly.   This worked for me in my f for years.  Ron

[Mooneymite]

I'm re-reading the Mooneyspace terms of service, but I think it is forbidden for O-360 operators to smirk when reading another IO-360 hot start thread.  

[gwav8or]

Kind of sounds flooded, and if you usually prime after a short taxi and it has been reluctant to start I would try not priming in the future. All your attempts may have flooded it more and then it takes a lot of cranking with the mixture in ICO and the throttle wide open to get it lean enough to fire. You can determine if it's really flooded badly by getting out and checking to see if fuel is draining out the sniffle.

Yeah when I got towed back to my hangar it was dripping fuel pretty good.


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[gwav8or]

One thing I forgot to mention was after trying the intentional flood and flooded start, I let it sit for 30 minutes before trying again with no luck.

Next time I’ll try the methods mentioned.


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[gwav8or]

I'm re-reading the Mooneyspace terms of service, but I think it is forbidden for O-360 operators to smirk when reading another IO-360 hot start thread.  

Quite honestly this hot starting issue tends to make me wish I’d bought a C or G instead. Love my F but these hot starts are for the birds.


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[PeteMc]

A friend with a 212 conversion always does what @Ron McBride suggested.  He runs up the engine to 11-1200 and then pulls the mixture.  He has a LOT less Hot Start issues.

 

[DCarlton]

59 minutes ago, gwav8or said:

Quite honestly this hot starting issue tends to make me wish I’d bought a C or G instead. Love my F but these hot starts are for the birds.


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Hot starts drove me crazy with my F until I got my engine overhauled.  Now hot starts are easy.  Except... for the scenario you describe; a short taxi to fuel then shut down.  I jokingly call that a cold/hot start.  I'm going to try what the folks suggest here next time; leave the controls where they are.  For me, the engine often sputters during a "cold/hot" start, and then dies and I have a bit of a hard time the second attempt (it happened today).  Never sure if I should prime a little or not.  Gonna try not priming for a while now and see how it goes.  I think I'll go ahead and let the engine warm up before taxi and not worry about it getting hot and then shutting it back down.  

[Ron McBride]

2 hours ago, gwav8or said:

Quite honestly this hot starting issue tends to make me wish I’d bought a C or G instead. Love my F but these hot starts are for the birds.


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If you still have problems, let me know.  We can get together.  I am near Poteau. KRKR.  Ron

[PT20J]

It helps to understand a bit how the RSA fuel injection system works. It takes some of the Voodoo out of it.

During cruise operation, the airflow through the servo controls the amount of fuel delivered to the nozzles to maintain the mixture set by the mixture control. But, at engine speeds lower than around 1200 rpm, there isn't enough airflow through the venturi to meter the fuel properly. Thus, the servo has a manual linkage connected to the throttle that controls the fuel flow at part throttle openings. Setting the throttle for approximately 1000 rpm (it doesn't have to be exact) will allow enough air and fuel through the servo for starting, but it still has to get to the nozzles.

Normally, the lines between the flow divider and the nozzles are full of fuel. On shutdown, when the fuel flow stops due to the mixture control being placed in ICO, the pressure at the flow divider drops below 2 psi and a valve shuts off fuel flow between the flow divider and the nozzles to ensure a clean shutdown. If the engine is cold, fuel remains in the lines between the flow divider and the nozzles. If the engine is hot, fuel vaporizes in these lines and they eventually empty.

So, if you shut down a hot engine and immediately restart it, there is no problem because the lines are still full of fuel. If you wait long enough, the lines are empty and it will take a lot of cranking (or a little prime) to fill them before the engine will start. Somewhere in between and there may be enough fuel in the lines to start the engine, but it will quickly die as the fuel is used up until the lines refill.

[Yetti]

Shut down at 1100 RPM with mixture close.   Don't touch anything, just crank.  When it pops add mixture.

 

You were working on possibly burning up the plane.   way flooded.

Edited July 29 by Yetti

[midlifeflyer]

7 hours ago, Yetti said:

Shut down at 1100 RPM with mixture close.   Don't touch anything, just crank.  When it pops add mixture.

 

Not in a Mooney but I did exactly this in a fuel-injected Lycoming last Tuesday. 

[C.J.]

@gwav8or Watch this video of Don Maxwell doing repetitive hot starts in a J.  It should eliminate 99.99999999% of your hot start issues. Cheers, C.J.

 

[gwav8or]

10 hours ago, Ron McBride said:

If you still have problems, let me know.  We can get together.  I am near Poteau. KRKR.  Ron

Poteau, nice!  I occasionally fly into KJSV to see family.

[gwav8or]

53 minutes ago, C.J. said:

@gwav8or Watch this video of Don Maxwell doing repetitive hot starts in a J.  It should eliminate 99.99999999% of your hot start issues. Cheers, C.J.

 

yeah, i've watched that video many times.  For some reason, that method only works some of the time for me.

[Shadrach]

15 hours ago, Mooneymite said:

I'm re-reading the Mooneyspace terms of service, but I think it is forbidden for O-360 operators to smirk when reading another IO-360 hot start thread.  

Smirking at a self inflicted wound is inhumane.  Like many problems in Aviation, the source is usually the soft, squishy bit behind the yoke. 

An IO360 will start just fine when hot by simply turning the key until it fires and enriching the mixture. The problem is most pilots new to the system are suspect of something so simple. They feel compelled to do something more to “help”.  When that doesn’t work, they grab the shovel and really get to digging. 

[gwav8or]

1 minute ago, Shadrach said:

Smirking at a self inflicted wound is inhumane.  Like many problems in Aviation, the source is usually the soft, squishy bit behind the yoke. 

An IO360 will start just fine when hot by simply turning the key until it fires and enriching the mixture. The problem is most pilots new to the system are suspect of something so simple. They feel compelled to do something more to “help”.  When that doesn’t work, they grab the shovel and really get to digging. 

"soft, squishy bit behind the yoke" here roflol

Yeah, it appears I used the extra large shovel yesterday......

So after a short taxi & refuel, how many (approx) blades should it take for the engine to sputter back to life?  I feel like it should be within a few (8-10) blades or about 4-5 full revolutions of the prop?  More? Less?

[Shadrach]

2 hours ago, gwav8or said:

"soft, squishy bit behind the yoke" here roflol

Yeah, it appears I used the extra large shovel yesterday......

So after a short taxi & refuel, how many (approx) blades should it take for the engine to sputter back to life?  I feel like it should be within a few (8-10) blades or about 4-5 full revolutions of the prop?  More? Less?

I’d estimate a range of 4 to 12 blades. It’s hard to say exactly because conditions vary and the state of the fuel in the lines after shutdown is dynamic. The burbling and sucking sounds you hear when putting the plane away is fuel expanding out of the injector lines and into the intake manifold.

So, while I can’t say exactly how many blades it should take to fire off when hot, I can say that it’s prudent not to add fuel to the situation until you’ve verified that it is required.  There are times when I have been slow on the mixture and failed to deliver fuel in time to keep the engine running after it has fired. When that happens you have two choices, a short, maybe 3 second prime or alternatively, you can crank and start feeding the mixture in (boost pump off) until it fires. I’ve used both with good success. 

[PT20J]

3 hours ago, gwav8or said:

yeah, i've watched that video many times.  For some reason, that method only works some of the time for me.

Well, the problem with the video is that even though the engine is hot, Don repeatedly shuts down and immediately restarts. That’s the easiest condition because the whole problem is the variability in the amount if fuel in the lines between the flow divider and the nozzles and when you immediately restart, the lines will still be full. 

[gwav8or]

6 minutes ago, Shadrach said:

I’d estimate a range of 4 to 12 blades. It’s hard to say exactly because conditions vary and the state of the fuel in the lines after shutdown is dynamic. The burbling and sucking sounds you hear when putting the plane away is fuel expanding out of the injector lines and into the intake manifold.

So, while I can’t say exactly how many blades it should take to fire off when hot, I can say that it’s prudent not to add fuel to the situation until you’ve verified that it is required.  There are times when I have been slow on the mixture and failed to deliver fuel in time to keep the engine running after it has fired. When that happens you have two choices, a short maybe 3 second prime or alternatively, you can crank and start feeding the mixture in with the boost pump off. I’ve used both with good success. 

Thank you sir!  Much appreciated!

[MikeOH]

Don’t be in a rush to add mixture. Crank and give it time…just be ready to get the mixture in once it fires. The idea being to be sure you’re not already too rich…if there is residual fuel it’s going to fire even if the mixture is cut off; if you bring the mixture in too soon you may flood it.