Hard to Start 231

[chrisk]

My m20K 231 usually starts right up.  I give it a few seconds on the primer, and the engine quickly catches, although it make take a few more shots from the primer to keep running until the fuel systems seems to have caught up.

 

The last two times I have tried a cold start, it has been difficult.  It just doesn't want to start.  It also feels like the starter is turning the prop a little slower. (the battery is fine)  Anyway, it sounds like a cylinder will catch, but then nothing more.  Also it is not really cold outside, maybe 65 degrees.  Also to get the engine to start, I've had to add more throttle in.

 

Has anyone else had this problem?  Could a weak started be part of the problem?  How can I tell if the primer is actually doing anything?  On the other hand, maybe I over primed it and it is as simple as I flooded the engine?  I'll experiment some this week, as we are going to have a few non-flyable days. 

[Awful_Charlie]

Is the impulse coupling ok? I would also check to make sure the spark plug gap is not too large. If the spark is ok, then give a good prime and watch to see if any fuel dribbles from the sniffle valve

[Parker_Woodruff]

Where do you live? If it is cold outside, give the fuel maybe 15-30 seconds after priming to vaporize a bit. Engine will fire up a lot sooner.

[schule]

My POH give a cold temp priming adjustment for the LB engine. I also wait several seconds to give the cold fuel a chance to vaporize. It might be a OWT but I have heard from some guy who read it on the google machine that 100ll is relatively stable for a gasoline and resists rapid vaporization to make it work per specification.

[chrisk]

Where do you live? If it is cold outside, give the fuel maybe 15-30 seconds after priming to vaporize a bit. Engine will fire up a lot sooner.

Hi Parker,

I'm just outside of Austin TX.  I'm used to starting the plane in 100 degree weather, so 50 to 65 degree temperatures are quite a bit colder. (and maybe why the prop seems to spin slower withe the starter).  I'll have to try waiting a little longer after priming.

[carusoam]

65°F is above the usual temperature considered 'cold'

Best regards,

-a-

[DonMuncy]

If your 231 is like mine, I wouldn't worry about flooding it. Mine seems almost impossible to flood. On mine, any reluctance to start requires more fuel. Try using the high boost pump for about 6 seconds and then the primer, using the primer per the POH (but on the generous side). Both boost and primer with throttle full in. The boost pump and the primer use the same pump, but deposits fuel in different places in the induction system. 

I might also double check the battery condition. If it is turning slower, chances are the available voltage is lower.

[Nemesis]

The first and very trusted mechanic that I used, Jason Doscher in MN, told me that it was almost impossible to flood an LB engine before a cold start. (Don got to that one before me.) I use a full 5 seconds of prime. I start counting only when I see the fuel flow gauge rise. Usually there is a change in tone when the fuel pump really starts to deliver fuel to the intake manifold. I also normally need to hit the prime button once or twice as the engine is starting to catch. I have never used high or low boost for starting but I have no doubt that method will work just fine as well. As Don mentioned above, the boost just puts the fuel into a different place - directly into the cylinders.

 

Dave

[jlunseth]

Here is my method, which I came to after reading this Avweb article on the Conti big bores http://www.avweb.com/news/airman/184350-1.html?redirected=1 and also talking to my mechanic at Willmar, and of course trying things that worked and that didn't.  This method, with small changes in the priming time depending solely on temperature, will work anytime, anywhere, at any ground altitude to start the TSIO-360-LB.

 

Most of the time, failures to start in the TSIO360 are due to interrupted fuel flow in the moments after the first cylinder fires.  At that point the engine is running on the primed fuel, and it may not be enough to keep the engine going until the mechanical fuel pump can start to move fuel into the cylinders.  So first, with the throttle and fuel control fully closed, run the high boost pump until the fuel pressure stablizes and for a couple more seconds.  This flushes out and fills the fuel lines. It does not matter what pressure the fuel stabilizes at, I generally see anything from 14 something psi to 17 something.  What you want to see, is a rise in fuel pressure to a point, and then a stable number.  If you do not have a fuel pressure readout, run the pump for 15-20 seconds.  The Avweb article says to run for 30 seconds, I don't and will explain why in a moment.

 

Second, with the throttle and fuel control fully open, prime the engine.  Priming time for me will range from 6-8 seconds in summer weather, to 12-15 seconds in cold weather.  Usually no more than 10 seconds unless it is really cold.

 

Then with the fuel control at full rich, close the throttle to about 2/3rds.  The reason for partly closing the throttle is so that when the engine starts, it does not zoom up to full power.  Put your finger on the high boost pump.  Hit the starter, and when the first cylinder catches, push the high boost button so the pump runs, but not so hard the switch locks into the full on position.  I usually leave the safety latch in place covering the switch, and just push one corner of the switch.  This will prevent the switch from locking full on.  As soon as the engine is running smoothly on its own, or if it starts to slow down because it is too rich, take your finger off the high boost button.  The engine should now be running happily.

 

After some experimentation, I concluded that running the high boost for 30 seconds to cool the lines and mechanical fuel pump, as is advocated in the Avweb article, does not work well in the TSIO360.  Supposedly, with the throttle and fuel control fully closed, all the excess fuel is routed back to the tanks rather than dumping into the cylinders, and therefore one can leave the high boost running for a fairly long period with no issues.  However, when I have tried that I can produce a backfire in the engine when it starts.  Running the high boost just long enough to stabilize the fuel pressure flushes the lines, but never causes a backfire or any other issue.

 

The reason for pushing the high boost button when the first cylinder catches, is that it takes a few moments for the mechanical fuel pump to push fuel to the cylinders.  During that moment, the engine will often exhaust the primed fuel it is running on, and stop because of lack of fuel.  Running the high boost at this point makes sure the engine gets the fuel it needs, and you should gets good starts every time, under all conditions, and whether the start is a cold start or a hot start.  I find that often, even if I have not been fast enough to get to the high boost and the engine is running down and starting to quit, if I hit the high boost button the engine will immediately fire normally and start.

 

I have tried other starting methods that I have read about.  For example, I read that a leaned out start was advisable at high altitude airports even though the engine is turbocharged.  I tried that at KLXV, it failed miserably and I nearly flooded the engine.  I reverted to my standard method, and the engine started instantly. 

 

I have also used the method to start the engine without pre-heat in temperatures below zero.  I do not like to do that, it is inherently hard on the engine.  But sometimes there is not facility at rural airports to plug in or preheat and you just have to do it.

 

All I can say is, it works for me every single time without fail.  What you are doing is getting the lines full of fuel before starting, and then using the high boost to run the engine for a short while until the mechanical pump is doing its job.  I tried using the prime button instead, but it does not work as well. As I understand it, the prime button puts the fuel in a different place than the boost button.  I am told the primer puts the fuel in the induction system, I surmise that is somewhere upstream of the intake ports.  The boost distributes the fuel just as the mechanical pump does, through the nozzles and right outside the intake port.  What I can say from experience is that using the high boost provides a much more dependable source of fuel flow than the primer button.

[Guest]

My m20K 231 usually starts right up.  I give it a few seconds on the primer, and the engine quickly catches, although it make take a few more shots from the primer to keep running until the fuel systems seems to have caught up.

 

The last two times I have tried a cold start, it has been difficult.  It just doesn't want to start.  It also feels like the starter is turning the prop a little slower. (the battery is fine)  Anyway, it sounds like a cylinder will catch, but then nothing more.  Also it is not really cold outside, maybe 65 degrees.  Also to get the engine to start, I've had to add more throttle in.

 

Has anyone else had this problem?  Could a weak started be part of the problem?  How can I tell if the primer is actually doing anything?  On the other hand, maybe I over primed it and it is as simple as I flooded the engine?  I'll experiment some this week, as we are going to have a few non-flyable days.

If the engine used to start normally and now does not you must determine what has changed. An engine runs on fuel, air and sparks, one of these must have changed.

Each of the three can be checked, clean air filter, check the induction system for leaks. Cylinder compression check per TCM SB 03-3. Pressure check of the exhaust system with a shop vacuum looking for leaks.

Clean, gap and test the spark plugs, high tension test the ignition wires, when was the last time the mags were checked internally? Last time a 500 hour mag inspection was done. Mag to engine timing per TCM MSB 94-8D.

Fuel injection nozzle cleaning, all upper deck air seals replaced with nozzle re installation? Fuel injection set up per TCM SID 97-3E?

Clarence

[chrisk]

All, thanks for the responses. There is no simple way to put this.  I should have been more diligent with the manual.  For the last 6 months or so, the temperatures have been 90+ degrees.  2 seconds of primer worked just fine.  As it got colder, I thought what the heck, give it 3 seconds total.  I opened the manual today, and saw for the current temperatures I should be priming about 10 to 12 seconds.  --It started just fine with that much priming.  And I'm blushing with embarrassment.

 

Also, the suggestions on the high pressure pump are really good. I didn't have to keep hitting the primer to keep the engine running.

[Marauder]

All, thanks for the responses. There is no simple way to put this. I should have been more diligent with the manual. For the last 6 months or so, the temperatures have been 90+ degrees. 2 seconds of primer worked just fine. As it got colder, I thought what the heck, give it 3 seconds total. I opened the manual today, and saw for the current temperatures I should be priming about 10 to 12 seconds. --It started just fine with that much priming. And I'm blushing with embarrassment.

Also, the suggestions on the high pressure pump are really good. I didn't have to keep hitting the primer to keep the engine running.

Well, we'll keep this little secret for you. Don't think there is a Mooney owner that hasn't done something similar.

[N201MKTurbo]

65F is very cold!

[DonMuncy]

I sure am glad I've never made a mistake.

[schule]

Wait till the real cold hits Texas tonight. Might even have a 1/4" of ice an cripple all travel options.

[Marauder]

65F is very cold!

Yeah right...

[chrisk]

 

Ok, now I know why it was hard to start.  I took the cowl off for a good visual inspection.  This is a picture of the primer line. I guess it started easily the last time after using the Don Muncy method of High boost pump for 6 seconds, then the primer.  Presumably the primer did nothing and the high boost pump did it all.

 

Anyway, the plane goes to the shop as soon as the shop can get to it. 

 

Has anyone else had this happen?  And what is it going to cost me?

 

P.S.  In any case, the plane seems to fly just fine this way/  It's only a small induction leak. 

[carusoam]

Is your mechanic skilled at welding SS?

It looks like it broke at the weld..

Best regards,

-a-

[Guest]

The line can be easily repaired with a propane torch and a bit of silver solder.

Clarence