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Backfireing

Iou

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My 0-360 A1A runs fine for about 10 minutes of flight then it will start backfiring and losing power upon landing shuts down and will not start until it cools down. It is a carburetor engine with only 50 hours since new. Any ideas where to start troubleshooting.
 
Are you saying it loses power so you need to land or as you are landing it backfires? I wish I knew more about engines to help but I am really interested in what you find out. I have noticed a backfire or 2 if I pull power too quickly on downwind but no issues with stalling or loss of power.
 
Let's be sure we are talking about backfiring versus after-firing (far more likely and less serious)...
 
Upon doing a touch and go the engine backfired on approach and when power was applied the backfireing increased to the point that the plane would not climb. After landing the engine quit and would not restart until it had cooled for a hour or so.
 
Upon doing a touch and go the engine backfired on approach and when power was applied the backfireing increased to the point that the plane would not climb. After landing the engine quit and would not restart until it had cooled for a hour or so.

That is scary. Best of luck getting that all figured out.
 
ok, I'll have ago :)
Is the engine magnetos or EI equipped?

Backfiring usually happens when unburned fuel get lighted in the hot exhaust. A couple of causes for this to happen, but with the few info crumbs you scattered around, difficult to diagnose more, but pointing towards an ignition problem...
 
Backfiring versus after-firing

Definitions matter here if the problem is to be understood.

After-firing happens when unburned fuel gets ignited in the hot exhaust.
Backfiring happens when ignited fuel burns backwards through the intake system (backwards to the normal airflow).
After-firing is commonly mislabeled as backfiring.
 
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Upon doing a touch and go the engine backfired on approach and when power was applied the backfireing increased to the point that the plane would not climb. After landing the engine quit and would not restart until it had cooled for a hour or so.

One candidate cause I'd look for is heat-induced vapor in the fuel lines. Some questions to help better understand the situation:

Was the boost pump on during the landing?
Are you using 100LL or auto gas?
Are the fuel lines forward of the firewall firesleeved?
Are there sharp bends in the fuel lines/fittings?

Do you have engine data that you can upload to Savvy Analysis and share?
 
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I would start in the carb, as fuel issues (either too rich or too lean) are most likely to cause this collection of symptom. This assumes that you are starting up a cold engine, warming for a brief time then taking off. My first guess would be an issue with the float or needle/seat attached to it. When problems arise here, it can overfill (too rich) or underfill (too lean) the carb bowl. Both can induce conditions that will present to the novice as an inability to smoothly make high power and apparent backfires. It could also be am misbehaving fuel pump. Clearly it is an issue in which heat is changing something and that something is causing the problem. However, in your scenario, most of the parts have not reached that high of a temperature within 10 minutes.

Larry
 
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Definitions

Maybe the third time will be the charm...

One comes out the air filter and the other out the tailpipe
 

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Maybe the third time will be the charm...

One comes out the air filter and the other out the tailpipe

Yes, we can keep telling the OP that (or maybe it was directed at me), but it is hard for a novice to understand the nuances of each of these and discern the difference in sound. The OP was sitting in the cockpit, so how would he know which orifice that the explosion came from? Best we just give him diagnostic aids based upon the likelihood of both. Excluding start up events, backfires at medium to high power settings (where the OP's symptoms begin) are uncommon without serious issues with the valve train or serious issues with ignition timing, so we can assume these were afterfires, as it starts and runs fine for 10 minutes before the issue reappears.

And yes, I know that the over rich or lean will cause afterfires, not backfires. But I am using the terminology that the OP understands. The vast majority of people call these backfires and as diagnosticians, have to work within the operators knowledge level.
 
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I would check fuel filter/ gascolator for dirt and water.
Remove fuel hose from carburator and run the starter for 10 s.
Check that there is fuel flow from the pump.
Run engine on LEFT magneto/ electronic ignition only. 700-2.000 rpm.
Run engine on RIGHT magneto/ electronic ignition only. 700- 2.000 rpm.
Don´t fly the aircraft before problem is resolved.

https://msacarbs.com/carburetor-troubleshooting/

Telephone 336-446-0002; FAX 336-446-0007;
or Email: [email protected]

Good luck
 
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