IO-390 Hot start

jkgoblue

jkgoblue

Pre-takeoff checklist
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John K.
I've been flying my Sportsman for about 3 months now and am looking for some tips on hot starting my IO-390. I've been basically doing it with very little throttle and no primer or fuel pump which seems to work fine (it fights it, but eventually starts) but runs rough afterward for a while.

Does anyone know a proven technique for a hot start on this engine? I've checked the Lycoming site and found that they suggest keeping the fuel pump on during "hot weather, hot engine ground operation where fuel vapor problems cause erratic engine operation" so I already know one thing I'm doing wrong. However, I could not find a specific hot start procedure.

There is a flooded start procedure which states "If there is flooding of the engine without a fire, the operator should open the throttle full and close the mixture; (see Operator’s Handbook on mixture) turn the engine over several times with the starter to clear it; then begin again with a normal start routine "

The Sportsman manual also states for a flooded start "Allow all the fuel to drain from the intake system before attempting to start a flooded engine then:

1) Open the throttle fully
2) Set mixture full lean
3) Engage starter. When engine fires, advance the mixture control and move the throttle to the desired setting."

I guess the only way to know that the fuel has drained from the intake system is to wait. (?)

I just was wondering if others had proven methods that work and don't hurt the engine.

Thanks.
 
jkgoblue said:
The Sportsman manual also states for a flooded start "Allow all the fuel to drain from the intake system before attempting to start a flooded engine then:

1) Open the throttle fully
2) Set mixture full lean
3) Engage starter. When engine fires, advance the mixture control and move the throttle to the desired setting."
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I have found that this works pretty well for a hot IO-360 as well. Keep the fuel pump OFF.
 
Tried and true way to start a hot fuel injected engine. Flood it from the get-go and perform the 'flooded' start procedure. At least that way you are starting from a 'known' condition instead of guessing how much non-vaporized fuel is left in the lines and wearing your battery/starter while coming to the conclusion that you guessed wrong.
 
VERY interesting... Not sure if his method works on Lycoming engines but I can't see why not.

The IO-390 runs hot so getting a way to cool it before the start seems like a good idea.
 
jkgoblue said:
VERY interesting... Not sure if his method works on Lycoming engines but I can't see why not.

The IO-390 runs hot so getting a way to cool it before the start seems like a good idea.
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I'm pretty sure Deakin's method (mine too) doesn't work on Lycomings. The TCM fuel injection has a return line from the engine driven pump which delivers all the boost pump fuel to the tank when the mixture is in idle cutoff and this is why running the boost pump for a minute can cool the pump. I don't think the Lycomings have such a return path and if I'm right, running the boost pump wouldn't accomlish anything good. I do agree with John that deliberately flooding the engine to start it is a bad practice with an all too high chance of starting a fire. AFaIK it also can result in excess cylinder wear if the excess fuel washes the oil off the walls.

I'll admit that I don't have much recent experience starting hot Lycomings but the procedure I've used that seems to work is to put the mixture in ICO, turn the boost on and crank right away while slowly moving the mixture towards rich with the throttle "cracked". An alternative is to set the mixture rich, start cranking with the throttle at 1/4 open then turn on the boost while continuing to crank.
 
I've never had a problem starting any hot Lycosuarus with 1/4 throttle, mixture full lean and boost pump off. Crank till she starts poppin' and move the mixture to 'bout half...if she starts to quit I pump the mixture full rich and it'll catch.
The Bendix RSA- systems don't have any way to vent the fuel left in the fuel-flow-spider-divider and the lines going to each cylinder after shutdown using the mixture control...the fuel percolates and, because it can't move backwards into the divider/fuel line it goes into the cylinders!
This is why the difference in the hot/cold start procedures...cold you are starting fuel poor and hot you are starting fuel rich...

JMPO

ChrisB)
 
I went upstairs and pulled out my Lycoming Operator's Manual - a fantastic reference manual with lots of performance graphs and procedures and details - and surprisingly (to me) there isn't a section with "hot start" procedures. They do, however, specify a different procedure for aircraft equipped with Bendix vs. Simmonds Type 530 injection systems. What's on your IO-390?
 
Their Key Operations Reprint says, regarding fuel boost pump use:

As an engine manufacturer, we are frequently asked about the proper use of the fuel boost pump with our power plants. Although we can’t pretend to be an expert on the fuel boost pump itself, we have some positive recommendations concerning its use with our engines. Where a boost pump is provided by the airframe manufacturer, and the airframe Pilot’s Operating Handbook has a limited treatment of the use of the fuel boost pump, perhaps this discussion can provide the necessary fuel boost pump information for the pilot in order to operate his or her engine as safely as possible.

It is necessary to supply the engine with a steady, uninterrupted flow of fuel for all operating conditions. Entrapped air, temperature changes, pressure drops, agitation in the fuel lines and other factors affect the release of air and vapor from the fuel system. Under some circumstances where an engine-mounted fuel pump is provided, it may not be able to pump a continuous fuel supply free of excessive vapor.

An effective continuous fuel supply is provided by use of the fuel boost pump. As a general recommendation, the fuel boost pump should be used with Lycoming engines in all conditions where there is any possibility of excessive vapor formation, or when a temporary cessation of fuel flow would introduce undesirable hazards. The conditions under which Lycoming recommends operation of the fuel boost pump are as follows:

1. Every takeoff.
2. Climb after takeoff unless Pilot’s Operating Handbook says it is not necessary.
3. When switching fuel selectors from one separate fuel tank to another, the fuel boost pump should be “on” in the new tank until the operator is assured there will be no interruption of the fuel flow.
4. Every landing approach.
5. Any time the fuel pressure is fluctuating, and the engine is affected by the fluctuation.
6. Hot weather, hot engine ground operation where fuel vapor problems cause erratic engine operation.
7. Some General Aviation aircraft require the use of the fuel boost pump during high-altitude flight. This will be spelled out in the Pilot’s Operating Handbook.
8. If the engine-mounted fuel pump fails.

If the fuel boost pump is used during ground operation, don’t fail to check the condition of the engine-mounted fuel pump before takeoff by turning the boost pump off briefly, and then back “on” for takeoff. If the engine-mounted pump has failed, it would be safer to know that on the ground rather than in the air when the fuel boost pump is turned “off.”

When in doubt, do the safest thing and use the fuel boost pump with Lycoming engines.

Don’t be “stingy” with the boost pump. In most cases, they last the overhaul life of the engine, and are then exchanged or overhauled themselves. AS A REMINDER, the airframe Pilot’s Operating Handbook is the authority if boost pump information is spelled out in it.
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All that said, what's always worked for me with Lycoming fuel-injected engines is the aforementioned full throttle / mixture to idle-cutoff crank-til-it-starts then 1/4" throttle and advance mixture routine. You learn the "fast hands" routine really quick... :)

The Mooneys I flew used an IO-360, and the procedures shown here worked well; they differentiate between hot and flooded starts.

http://www.mooneyland.com/Starting_a_Mooney.htm

Hot Start: Not so Easy!

1. DO NOT TOUCH MIXTURE. LEAVE IN IDLE CUTOFF.

2. Master on.

3. Crack Throttle 1/4"

4. Boost pump ON for 3 full seconds and then immediately off.

5. Engage starter.

6. When engine begins to catch, immediately enrichen mixture and then immediately begin to pump throttle quickly in and out about 2-3" of movement back and forth.

7. Once engine is running, lean mixture way back until you get a raise in RPM.

IF YOU DON'T MOVE QUICKLY ENOUGH TO GET THE ENGINE STARTED THE FIRST TIME WHEN WARM, THEN YOU SHOULD DO A FLOOD START, SO ATTEMPT TO GET HER RUNNING THE FIRST TIME.

Flood Start

1. Mixture Rich

2. Throttle Full Forward (firewall the throttle)

3. Boost Pump ON 3-5 seconds

4. Boost Pump off immediately

5. Keep Throttle Full Forward

6. Mixture Lean

7. Immediately engage starter

8. Once engine begins to catch, immediately richen mixture with the right hand, and retard throttle with the left hand.

9. Pump Throttle as described in number 6 in the Hot Start directions.

10. Do number 7 in the Hot Start Section above.

The idea here, especially in the hot start mode is to move quickly and not get distracted. Attempt to do the above with purposeful and deliberate motion, almost like choreography. With practice, you will get faster, and as you progress, your hot starts will no longer be an embarrassing thing to witness and it will take less stress of off your starter as well as wiring system. Also worthy of note is that there are no two engines exactly alike and you may have to alter the above somewhat to suit your E, F, or J models specifically, but this is the procedure I use when starting these engines that I had not started before and it usually works well on all of them. Remember that you are running the mixture very lean to get that rise in RPM, but when you have to add throttle, advance the mixture some and then retard once you're on your way taxiing. This is important and saves you from accidentally add take off power with the mixture leaned should you forget to enrichen the mixture on take off. Having the mixture way back for idle and taxi once taxi speed is achieved, the engine will fall on its face should you attempt to apply take off power with the mixture not full rich. The benefit to idling the engine while mixture is lean (Lycoming only. Do not lean mixture on the turbo models. They won't run well) is to keep your spark plugs from fuel fouling for a cleaner run up at which time the mixture should be full rich, and then leaned again until cleared for takeoff.

Questions I get when hot starting the Lycoming is why do you add boost pump if the mixture is at idle cutoff? Fair question and the reason is that you are basically pressurizing the fuel system behind the mixture cutoff so that when you richen the mixture, there is fuel pressure behind that and the engine will not starve for fuel once you rich the mixture.

The above is not intended to replace your checklist, but simply a way to start your Lycomings when the check list progresses to "Start the Engine". Of course you will want your radios off when ever you start your engine.

One of the best accessories you can add is the Sky Tech light weight High Speed starter. This starter turns the engine over about twice as quickly as the standard starter and makes a huge difference when hot starting. If you would like ordering information on this starter, send us an email and we'll get you the current price, availability, and get it shipped to you. And then sell your old starter on Ebay :eek:) to recoup part of your wise investment.

STARTING THE TURBO CHARGED K MODELS IS USUALLY MUCH EASIER DUE IN PART TO IT ALREADY HAVING A HIGHER SPEED STARTER AND SIX CYLINDERS WHICH IN ALL CASES IS EASIER TO START THAN A 4 CYLINDER ENGINE. You simply get 50% more cylinders to fire adding to the ease of engine starting.
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Last edited:
colomtnflyer said:
Maybe Ted has some ideas on this? After all, he works for Lyc....
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Right, because engine manufacturers have a clue about engine operation :confused:

I'd try Lance's method. On TCM engines, Deakin's method works very reliably. Either way, flooding, while it has benefits, isn't a good technique.

-Felix
 
TangoWhiskey said:
I went upstairs and pulled out my Lycoming Operator's Manual - a fantastic reference manual with lots of performance graphs and procedures and details - and surprisingly (to me) there isn't a section with "hot start" procedures. They do, however, specify a different procedure for aircraft equipped with Bendix vs. Simmonds Type 530 injection systems. What's on your IO-390?[/qu

Gee, I don't know... I'll have to check and see.

But alot of the information here is very helpful. It seems that most feel keeping the mixture out and very little throttle is the consensus standard at initial start. After that, it all depends on what happens next.

But I'm not sure there is one definitive answer. If it starts, then maybe that's good enough, no matter how you do it. I just don't want to do damage to the engine.

Thanks
Click to expand...
 
jkgoblue said:
It seems that most feel keeping the mixture out and very little throttle is the consensus standard at initial start. After that, it all depends on what happens next.
Click to expand...

Regarding the throttle setting; I was taught during a new airplane checkout something that was one of those "aha, why didn't I think of that" techniques, that has worked quite well for me.

On restarts after fueling or lunch or whatever, I leave the throttle alone, I don't adjust it to 1/4" or whatever.

Reason: it had been idling REALLY nice when I shut it down, at the exact setting it's at right now. So if it hasn't been moved, I'm going to be idling really nice when it fires up on the restart, with no need to quickly adjust the throttle to a "good" RPM setting.
 
TangoWhiskey said:
Regarding the throttle setting; I was taught during a new airplane checkout something that was one of those "aha, why didn't I think of that" techniques, that has worked quite well for me.

On restarts after fueling or lunch or whatever, I leave the throttle alone, I don't adjust it to 1/4" or whatever.

Reason: it had been idling REALLY nice when I shut it down, at the exact setting it's at right now. So if it hasn't been moved, I'm going to be idling really nice when it fires up on the restart, with no need to quickly adjust the throttle to a "good" RPM setting.
Click to expand...

That can work very well if you set the throttle to get 1000-1200 RPM before shutting down on most horizontal opposed engines. If you shutdown with throttle(s) closed they usually need to be opened slightly to get a good start as this allows the engine to make enough power on fewer than all cylinders to keep running.
 
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