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M20K dying


252Turbski

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My 252TSE is currently dying after start. It starts and runs fine for about 3-4 seconds then dies. If you keep feeding it fuel by using the boost pump or priming it will run fine. Also once it is warm it runs with no problems and no boost pump required. Does anyone have any ideas of the possible cause? New to mooneys. Thanks

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Transition training would have explained this for you...  of course, if your TT happened four months ago...   :)

Got any OAT you would like to share?  Where are you located?

Chances are you are explaining the operations of a Continental motor in cold weather...

The K has one of the most elaborate priming systems... it helps to be very familiar with the details of when to use what switch... for how long...

The 252 is a highly refined engine in all of the Mooneys...

You probably have a cold weather starting procedure... 

My POH is missing the keep running portion after start... the Lo-boost is the switch for my IO550... it will run continuously with this on.

After it Warms up a bit, turn the switch off, momentarily, to see if it is warm enough...

 

There is also plenty of experience to be gained if you are using an engine pre-heater...  :)

It’s getting a bit late, but @gsxrpilot may be around...

Welcome aboard,

-a-

 

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Obviously check the tightness of fuel fittings, tank vents, etc.  

Please see when the fuel system was last overhauled. If more than 10 years or so, send it off for overhaul.  Also, ensure the rubber has been recently changed in the tank selector and floor drain.  My 231 was 13 years after overhaul and you wouldn’t believe how many dry rotted o rings came back with it.  I can recommend an overhaul place if you would like.

Don’t end up like me at 50kts on the runway and just having the engine quit  

 

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4 hours ago, 252Turbski said:

My 252TSE is currently dying after start. It starts and runs fine for about 3-4 seconds then dies. If you keep feeding it fuel by using the boost pump or priming it will run fine. Also once it is warm it runs with no problems and no boost pump required. Does anyone have any ideas of the possible cause? New to mooneys. Thanks

Welcome to Mooneyspace.

In all likelihood your fuel injection system is in need of some adjustments.   Ask your maintainer if he/she is familiar with Continental S/B SID97-3G?  It covers the procedures, there is also an alternate method in the downloads section, look under “engine reference manuals”

Clarence

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When i first transitioned to my 231 I had lots of failed starts in the first time using the primer.

The engine dired fine, ran 3-4 seconds and then started to die or died. Feeding it with the primer pump fro several seconds prevented that, but always gave me a roraing engine spooled up to 2000 or more RPM and forced me th pull back the throttle - and the engine sometimes died again.

Anything changed by accepting a method from here:

- Full rich

-  Throttle wide open

- Then use the high boost pump for 6-8 seconds (8 in winter)

- wait for ~ 10s

- close throttle to position for ~1200RPM

- crank the engine

I never again have seen the engine dying. It runs smooth from the first second with ~1200-1400 RPM.

May be thuis can help you

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When the engine sits the fuel drains out of the lines. When you prime the engine, it starts off the priming fuel but when that is gone there is no fuel to keep running while the engine driven pump tries to get them full. The high boost is useful to refill the lines.  Do you have a fuel pressure readout? If you do, pull the fuel to idle cutoff and the throttle closed.  Run the hi boost until the pressure stabilizes at some number, don’t worry about what the number is, just run the pump until the number stops going up.  Then make the MP and fuel flow full open.  Run the primer for six to eight seconds.  

The high boost button is under a red safety cage, and if you leave the cage over the switch and just push the upper corner of the switch it acts as an instant on - instant off switch.  You can use it that way whey you run the high boost to fill the lines, don’t open the cage, just push the top of the switch.  

Then when you engage the starter keep your finger on that switch.  If the engine starts to fire but begins to wind down, hit the high boost again. That will keep the engine going until the mechanical engine-driven pump takes over. When the engine driven pump starts to work just take your finger off the hi boost button and the high boost stops.

The one thing you need to know about any method involving running the high boost before start, is that it is possible to overdo it. Supposedly in a Conti you can pull the fuel to idle cutoff and run the high boost for a full minutes, which uses the fuel to cool the pump and fuel system and clear vapor lock in hot weather.  There is an article out there by the GAMI/APS guys advocating this method.  Don’t do it.  Running the high boost any longer than it takes to  stabilize the fuel pressure is the one and only way to get my engine to backfire, and you don’t want a back fire. Just run the pump long enough to get the pressure up. The number I get is 15.7 into the 16’s, it varies some every time.  You are not worried about that, just that it comes up and stops rising.

I use this method routinely, every start, it works in hot, cold, high altitude and normal starts.  I have started the engine on a few occasions at zero when it got left unplugged by the line guys.  I started it at Leadville this way when the POH procedure for high altitude did not work.  It works every time, everywhere.

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Yep, I fly a 252 based in Denver... where it's cold. But it's also high altitude.

I was experiencing similar hard starts in below freezing temps. But the fix for me was to pull the mixture back about an inch. I was actually flooding the engine at full rich. 

What works for me... very consistently

10 seconds of prime, mixture set about an inch out for the altitude, throttle about three quarters.
Crank and as soon as it fires, hit the prime again for 2 or 3 seconds.

I also have an engine heater. I do find that if I'll leave the engine heater on which keeps the oil at about 65 degrees, it starts much easier.

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I start every time the same and get the same stumble you had noted.

Leave throttle at 1100rpm when you shutdown, close the mixture.

When starting LEAVE the throttle there. Mixture at full and run primer for 3-10 seconds, more when cold.

Wait a couple of seconds, then crank. It should catch right away but might stumble a little. Run the primer again ( hold it down ) until it stabilizes. Lean mixture once stable to highest rpm.

 

 

I think the stumble is from fuel draining out of the injection system and some time for the mechanical pump on the engine to get the fuel back up to it.

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3 hours ago, 252Turbski said:

Wow! Thank you for all the responses. I am going to try all of these and test what works best. Seems to me the mechanical fuel pump doesnt like to hold pressure very well(at least when cold, Iam in seattle). I will come back with the results later this week.

btw the engine is the TSIO-360

I'm in Seattle today and tomorrow. I'd be happy to come by and see how it goes. I'm not an A&P but have been flying a 252 for the last 4 years or so. Of course, it's not cold today here in Seattle.

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@252Turbski  I had the exact same issue with my 231 as you described. Had to keep it alive with the primer and electric boost pump until it “got warm”. Once it “caught” it was good to go. You could start and stop it at will while it was warm. Changed out mechanical fuel pumps, ran fuel system checks, the whole 9 yards looking for it. Ended up being the fuel spider. Had that overhauled for like $700 and now she starts every time with zero issues. 

Edited by Mike A
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On 2/10/2020 at 4:57 AM, jlunseth said:

 

The one thing you need to know about any method involving running the high boost before start, is that it is possible to overdo it. Supposedly in a Conti you can pull the fuel to idle cutoff and run the high boost for a full minutes, which uses the fuel to cool the pump and fuel system and clear vapor lock in hot weather.  There is an article out there by the GAMI/APS guys advocating this method.  Don’t do it.  

 

I'm curious why you advise to not doing this to cool the lines.

I have a Rocket with the TSIO-520-NB. Starting these hot is a real pain. 

I've tried the cooling technique before. Throttle full, mixture cutoff, high boost for 60 seconds. My Shadin FF never registers a flow, stays at 0 GPH while doing this.

It has worked a couple of times. I live in the desert so trying to restart when its 105 outside is no fun. 

It seems my best luck is when following the procedure in the Rocket POH for a hot start.

It's hot start procedure is to flood the engine and do a flooded start. Its unfortunate but it works in the heat.

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Just now, Captain Bash said:

I'm curious why you advise to not doing this to cool the lines.

I have a Rocket with the TSIO-520-NB. Starting these hot is a real pain. 

I've tried the cooling technique before. Throttle full, mixture cutoff, high boost for 60 seconds. My Shadin FF never registers a flow, stays at 0 GPH while doing this.

It has worked a couple of times. I live in the desert so trying to restart when its 105 outside is no fun. 

It seems my best luck is when following the procedure in the Rocket POH for a hot start.

It's hot start procedure is to flood the engine and do a flooded start. Its unfortunate but it works in the heat.

The first time I tried the "60 second cool" was several years ago, shortly after I came back from the APS seminar where they talked about it.  Two instructors were walking by the aircraft at the time and they told me later that there was fuel pouring out of the engine compartment as I ran the boost pump.  Since then, if I push the pressure up to the stabilize point and then keep running the fuel pump for awhile, I will get a backfire.  It may be the 231 and not other Conti's, but I can tell you that in the 231, running the high boost for an extended period will cause a backfire.  

I had the fuel system and pump rebuilt last year and found that it took less time to get the pressure up to a stable point.  One of the first times I did that I kept the pressure on too long and sure enough, got a backfire.  That had not happened for a few years.  I watch the fuel pressure on my JPI and run it up to the point where the increase in pressure starts to slow down appreciably and stop at that. 

If the cooling technique works in your big bore go for it.  One of the issues with the APS seminar, and I will say it was a minor issue, was that the guys at GAMI had limited experience with the small bore turbos such as the TSIO360 in my aircraft.  They are Beech guys, and that is what is primarily used in the Bonanza, etc. I still have the course book at home, the last half of it is engine manuals from some of the popular large bores, but no manual for the TSIO360. I think the 360 acts differently than what their experience is.  Supposedly, with the fuel at idle cut-off, the circulating fuel is pumped back to the fuel tank via a return line.  I have the fuel system diagram for my aircraft, there is such a return line, but why excess fuel gets someplace where it can cause a backfire, I can't tell you.  If the fuel is truly cut off, there should be no flow at all to the nozzles, and thus no fuel for a backfire, but for some reason that is not the case.

I am just going from experience.  I don't use the prolonged high boost run to cool the lines because of the backfire issue, and because I don't have to.  If there is vapor in the lines and the engines fires, then starts to quit because of the vapor lock, I just push the hi boost switch in the "instant on" configuration (switch cover over the switch) and it will run the engine as long as I hold the button down and until the engine runs on its own.  Starts first time every time under any conditions that way (except extreme cold).

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