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Help with hot starts

Jasonm

Well Known Member
Hi all,
I could really use some help on hot starting my IO540. It seems no matter what I do from priming to not priming to holding my tongue a certain way that nothing works.

I can finally get it to start after cranking for what seems too long and leaning out the mixture. I have the basic mechanical fuel injection with a boost pump and without a return line.

Can others please post their methods with a similar setup?

Thanks
 
Assuming your engine cranks over at the full starter speed...

There are TONS of threads and posts on this. I suggest doing a search to save a lot of people a lot of time typing. To get you some info though here is how I hot-start my IO-360 and there is no reason it won't work with a 540.

1. crack the throttle
2. mixture ICO
3. start cranking the engine
4. SLOWLY move mixture forward
5. when engine fires slowly move throttle forward
6. boost on if necessary to keep fuel pressure up

This is what hundreds of Bonanza, C-182, C-201, Mooney etc. pilots use successfully. There are other excellent methods, and I've tried them all but this is what works every time for me.

Let us know what you find out.
 
In the 6 hours on my RV10, I've had only 2 hot starts. Both went very easily. I did the following. Very similar to previous post.

1... Mixture Idle cut off.

2... Boost pump on for a few seconds. This pressurizes the line up to the servo and should eliminate any bubbles but doesn't flood the cylinders.

3... Crack the throttle just a little - the same as for a cold start.

4... Crank while slowly advancing the mixture toward rich.

This procedure worked for me twice in a row. Not exactly overwhelming statistics. But it's something to try.
 
Agree with the above, usually works a dream.

That said, here are some other ideas. First thing I would do is check the mags or electronic ignition - check timing, check impulse etc. Make sure you have ignition available at the correct time.

Then

The solution starts with a question - how long has the engine been off ?

I am very familiar with IO-360, IO-540 and Continental IO-520 and can add a little for each.

0-10 Mins

Pump off, throttle cracked a tad - enough so that it is where you went from idle to say 1,000 rpm. Try it when running and see where the throttle is. Mixture ICO. Crank until first sign of firing then smoothly bring mixture to full rich, adjust throttle and be ready to run the pump if stumbling occurs. This is because our RV's are tightly cowled and retain heat so there may be bubbles of vapour in the firewall forward.

10-30 Mins

This is the interesting area usually as the motor doesn't know what it is doing ! You need to know what fuel system you have - is it direct to fuel servo or does it have a return line to the tank ?

A. No return line - try method above. If no success, mixture rich, throttle part open, run the pump for 2 - 3 seconds only. Back to start, mixture ICO, throttle cracked, crank and smoothly bring mixture out of ICO upon first sign of firing, be ready for fuel pump to keep it running smoothly.

B. Return line - Keep mixture in ICO and throttle open a way. Run fuel pump for 5 seconds to purge the line of any vapour. Back to start, mixture ICO etc etc.

After that you are out of reasons why a motor like that won't start unless there is something lurking in the induction system or ignition system :D
 
Thanks for the info guys. I hadn't been attempting a hot start in the manner described and it's obviously why my starts are very rich. I'll try the methods posted.
 
Hot starts are difficult because the engine bleeds fuel out the injectors post shutdown and as a result the engine is almost always flooded. Generally, the LAST thing you want to do is add even more fuel. No prime, no boost, mixture in ICO and crank while slowly opening the throttle. Eventually, the excess fuel will be blown overboard and the mixture will fire. As soon as it does, add mixture, adjust throttle and you are golden. If the stumbling idle that follows bothers you (doesnt hurt anything), then throw the boost on to minimize the vapor.
 
my experience

Following the procedures similar to what others have already replied with, I have had not issues with hot starts in my RV7a with an IO360. However, with my RV10 with an IO540, I had a terrible time with hot starts until I installed an iStart system. Check out this link:

http://www.istartair.com/

Check it out. We flew some 50 hours this summer with numerous hot starts and never once had an issue.
 
What kind of ignition setup you have? Van's had been shipping IO-540 engines with a straight and a retard mag, and they forget to mention (or at least they used to) that you need a SlickStart module. Without that you don't have a strong enough spark for hot starts. Just one possibility...
 
What kind of ignition setup you have? Van's had been shipping IO-540 engines with a straight and a retard mag, and they forget to mention (or at least they used to) that you need a SlickStart module. Without that you don't have a strong enough spark for hot starts. Just one possibility...

Sorry about that, knowing the ignitions would help.
Current ignition setup is one Lightspeed and one mag without the SlickStart module. I always start on the Lightspeed and then turn the key switch to both.
 
What kind of ignition setup you have? Van's had been shipping IO-540 engines with a straight and a retard mag, and they forget to mention (or at least they used to) that you need a SlickStart module. Without that you don't have a strong enough spark for hot starts. Just one possibility...

While a booster (or EI) will certainly help, it has been my experience that they aren't required to get the fire lit. My Rocket flew quite a while on straight Slicks. No issues with starts - hot or cold.
 
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While a booster (or EI) will certainly help, it has been my experience that they aren't required to get the fire lit. My Rocket flew quite a while on straight Slicks. No issues with starts - hot or cold.

Well, I'd say here are no absolutes as there are a number of variables involved that will affect starting -- battery age, time on the starting mag, etc. There have been cases where 540s started just fine on a retard mag alone without a starting vibrator (eg SlickStart). But over time, starting became progressively more difficult to the point of not starting at all.
 
FWIW - I have the Van's standard ignition - 2 mags, 1 retard, and a Slickstart. Simple has worked for me for the occasional hot start independent of 'how hot'.

I keep the boost pump off, crack the throttle just as for a normal start, leave the mixture alone and start cranking until something fires. Then I feed in some mixture and rumble along until things settle down.

If nothing fires I stop cranking. Turn on the boost for 2 or 3 seconds, turn it off, and try again. If nothing fires at that point, it's a cold start and I just do the normal stuff.
 
if your doing a short turn around, after shut down open your cowl oil door and let some heat escape while your fueling, eating, etc.

Having owned a Turbo Saratoga (a beast when it comes to a hot start) I was taught this method. It has always worked well for me.
First method: Do not turn on your fuel pump to prime. Mixture off, throttle full open. Crank the engine. If it starts have your hands on both the throttle and mixture because things happen quick. Bring mixture open and reduce throttle quickly to idle, and as needed to avoid high RPMs.

If it doesn't start after an attempt, open mixture, run fuel pump a couple seconds max, then off. Then follow the same procedures as above.
 
We were also having hot start problems with our IO375, dual PMags, Precision Airmotive EX-5VA1 no return servo. Tried different procedures. Latest one that seems to be working is taken from Diamonds manual using a similar engine and procedure used by local Aztec owner. Namely - like others, but leave the boost pump on. Throttle open to 1000 rpm spot, mixture ICO to full rich for 1 to 3 seconds hot, 3 to 5 seconds cold. Crank with ICO & advance mixture as engine fires. I have printed this procedure to a revised checklist but haven't laminated it yet - we'll see.
 
Not IO540 but IO360 hot start issues

G'day

I used to have huge issues with my io360 hot starts in the RV7A. Other planes with the same setup would start effortlessly in comparison. It got to the point I hated going anywhere unless it was overnight and I could cold start.

Finally discovered that there was a range of Slick Mags that had a wear issue with the cam. Mine wasnt in the list of affected mags, but was 'just' outside the range. Basically, the wear caused the mag to advance so the spark was further BTDC. Mine got out to about 33 degrees BTDC instead of the 25 expected. I ended up replacing the mag... no more hot start issues.

Current hot start procedure is described above:

Crack throttle, turn the key, feed in mixture until it fires..... works EVERY time now.

I found a multitude of hot start procedures when investigating the original issue. I have a 2 page Word document with them all listed! One thing I have followed is to let the engine idle at 1000rpm prior to shut down for about a minute. Don't know if its really helping, but I'm not going to complain when my aircraft now hot starts easily.

No longer worried about going out for that day trip and having to hot start at any time.

Cheers

Wayne
RV7A
Western Australia
 
a bit different approach...

I take a somewhat different approach from above. I make and assume flooded. I prime for 2 seconds with throttle at idle, mixture in. Then quickly put it at full throttle, mixture full lean, start cranking til start then quickly put throttle in followed by mixture in. The only way to clear out gas from the cylinders is with the throttle advanced, the more the better for clearing a flooded engine. Very rarely have I ever had to use more than one shot at a hot start. This results in a bit more a rpm burst, but usually under 1500, it is a hot, so a lubricated engine for the most part; hence, the extra RPM does not worry me compared to a normal cold start where I shoot for 1000 RPM. Works well on the all the IO-engines I have flown which is quite a few 4 and 6 cylinder models.
 
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