C 172 Starting Procedure

[ClipperLuna]

Ok, did this and it started on the second ignition attempt, then I shut off the mixture to stop the engine and it started again without any more fuel pumped in for the next four try's on the first ignition attempts. Then I tried the same amount of fuel pumped in as the first attempt and it failed to start at all with battery dying.

This is with the engine temp at just under 150. I'll have to try sticking the plane somewhere very cold and see how that goes. Still very confused on the priming situation.

Sorry, I meant try the priming technique I just described (advancing to a count of "one" and all that) with a cold engine. By cold engine, I mean one that has been shut-down for at least a few hours, preferably at a temperature above 15C. If the engine is at 150F, you shouldn't need to prime at all. What I'm having you do is add just a little bit of primer at a time and gradually increase the amount you add to find the "sweet-spot" at which your engine will start without a fuss (or without much fuss, anyway). See if you can reliably get a cold engine started when it's been sitting at mild temperatures before you try a cold-weather, less than 0C start.

[WhiteHawk77]

Ok, Welsch, you are misinterpreting a little, I understand that the engine needs to be running for a bit for the battery to get its charge back, which is why I made sure to go in the hanger and recharge it all the time (must have done that a hundred times now), as for why I primed again, well I'm testing things here, trying to work out what works and why, in this case priming for about 1-1.5 seconds worked the first time with a warm engine, then worked without priming for the next four attempts starting more easily than the primed start did, then priming the same amount after that meant I could not start the engine (making sure to charge the battery and making sure the starter was fine between every attempt), I need to know why, same conditions, same engine temp, different result, why, what changed? Was there still fuel from the good starts in there and priming the last time even if it was very little made it flood?

ClipperLuna, I just tried again with a OAT of 15c and engine temp of the same, does not start with 1 second, 2 seconds, 3 seconds, 4 seconds or 5 seconds with mixture at 50%. No prime also fails. I also sent my plane to Antarctica at -18c and waited till the engine temp was even colder and did the same 1 second or so at 50% mix prime thinking it's never going to start! started fine, aaaaagh.

Am I right in thinking that accusim models fuel fumes? If so I guess a few seconds of fuel prime would flood a cold engine with warm OAT? If so that would explain the major trouble I had with starting it when I first got the plane the other night but there is still inconstancies that I can't work out, sometimes it won't start and sometimes it does with same conditions and actions, wish I could get a handle on it.

PS: Autostarted, shutdown with mixture, restarted manually with no prime, started fine.

[domini99]

Ok, Welsch, you are misinterpreting a little, I understand that the engine needs to be running for a bit for the battery to get its charge back, which is why I made sure to go in the hanger and recharge it all the time (must have done that a hundred times now), as for why I primed again, well I'm testing things here, trying to work out what works and why, in this case priming for about 1-1.5 seconds worked the first time with a warm engine, then worked without priming for the next four attempts starting more easily than the primed start did, then priming the same amount after that meant I could not start the engine (making sure to charge the battery and making sure the starter was fine between every attempt), I need to know why, same conditions, same engine temp, different result, why, what changed? Was there still fuel from the good starts in there and priming the last time even if it was very little made it flood?

ClipperLuna, I just tried again with a OAT of 15c and engine temp of the same, does not start with 1 second, 2 seconds, 3 seconds, 4 seconds or 5 seconds with mixture at 50%. No prime also fails. I also sent my plane to Antarctica at -18c and waited till the engine temp was even colder and did the same 1 second or so at 50% mix prime thinking it's never going to start! started fine, aaaaagh.

Am I right in thinking that accusim models fuel fumes? If so I guess a few seconds of fuel prime would flood a cold engine with warm OAT? If so that would explain the major trouble I had with starting it when I first got the plane the other night but there is still inconstancies that I can't work out, sometimes it won't start and sometimes it does with same conditions and actions, wish I could get a handle on it.

PS: Autostarted, shutdown with mixture, restarted manually with no prime, started fine.

I prime 3 to 5 seconds. It always starts for me.

[taildraggin68]

Hey guys, this isn't based on anything properly researched and completely a hunch, but when you have trouble starting the 172, and it just won't fire, reload the vehicle, in FSX or P3D, and it may help to reset the accusim parameters leading to inability to start. I have had success with this method on the only two occasions that the 172 wouldn't start. Now I know that you're not going to "reload user vehicle" IRL, but IRL you're not beating your head against accusim either Only a suggestion and mileage may vary, but if you don't want to use auto start, then give this a whirl redo you're start sequence.

[domini99]

A way to start your 172 after flooding it, is by using just a little bit of mixture, half throttle, and then crank.

[aprewett]

Wanted to add my voice to the mix, I also am having starting problems. For this thread the starting technique seems different from what was in the manual. I don't recall mention of advancing the mixture to full on ignition. I have not had a chance to try the different techniques listed yet, but hopefully I can get away from auto-start.

Allan

[Leadcatcher]

A way to start your 172 after flooding it, is by using just a little bit of mixture, half throttle, and then crank.

On the starting procedure - I'm actually taking lessons in a 172S and the starting procedures in the A2A are pretty spot on. You do need to be careful of flooding, instead of time - watch the fuel flow and once you get a positive file, cut the pump, clear the prop then crank, once it catches go to full rich, check oil pressure, then idle - make sure to lean the mixture as required for taxing. If you flood, domini99 posted a great procedure


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[ClipperLuna]

I experienced something this weekend that may give an insight into how easily this thing can flood. Went to start it up and did my usual mix to 50% for a count of three, which is about one second. Didn't fire. Tried again but only counted to two, or about 2/3 of a second. This time it fired right up. OAT was 18C. Has anyone else gotten it to go with less than a second of priming?

[Oracle427]

I always give 5 seconds at full rich before every start. Are you waiting for the engine to start before feeding in any mixture or do you start to gradually feed in some mixture as crank the engine?

Also you do have the throttle open a little correct? It should be around 10% open.

[ClipperLuna]

I always give 5 seconds at full rich before every start. Are you waiting for the engine to start before feeding in any mixture or do you start to gradually feed in some mixture as crank the engine?

Also you do have the throttle open a little correct? It should be around 10% open.

It's probably closer to 15%, but yes, the throttle is open a little. Regarding the mixture, I've tried it both ways: wait for the engine to fire before I enrich the mixture, and enriching it immediately after cranking the engine. I don't notice any difference as far as ease of starting goes. (I won't go so far as to say there definitely is no difference, I just don't notice one.) It won't start if I use 3 or more seconds of priming.