engine stoppage after startup

[rv7charlie]

The only thing about auto fuel & winter that might make sense to me is if you have summer blend during really cold weather. it might go lean due to poor vaporization of the summer blend mogas.

FWIW, I've had similar issues with various a/c engines, both carb & FI, both mogas and avgas, in cold weather. If they have stock ignition, they are basically at best '50s-era car engines (or more accurately, '30s era-farm implements) when it comes to starting.

Charlie

[sailvi767]

Originally Posted by prkaye

Weird... I am using Shell V-Power: 91 Octane no ethanol auto gas. I started using this fuel this summer. Today was probably the coolest day I've run the plane on this fuel, but it was still above freezing.
Interesting... I wonder why the cold weather would cause this on auto fuel? if this turns out to be the cause, I guess I should switch to avgas for the winter.

One thing you have to keep in mind with auto fuel is that formulations change all the time and are often seasonal. It could be the fuel your using now has some different characteristics then what you had a month ago.

George

[Steve Barnes]

I remember many years ago when I was experimenting with auto fuel in my RV4, that I often had my engine quit after a few rotations. The restart was always with out incident. I went back to 100 LL and never had it happen again. I was more concerned about the auto fuels effect on the O-rings and seals than how the engine operated with it. The old style O-rings on the fuel caps expanded so much that they fell out of the grooves. As soon as I went back to 100 LL they shrunk right back to size.

On my new plane with fuel injection, during hot starts the engine almost always starts then quits, (vapor) the second start attempt is always successful. This only happens with a heat soaked engine.

Steve Barnes "The Builders Coach"

[DennisRhodes]

Had never happened before on 100LL but one cold morning the O-320 did stop rather abruptly after cranking on 93 ( no ethanol) but restarted immediately. Have been running one side with 100LL and the other mogas all summer usually tried to switch back to 100 LL on return to the pattern but may have not run all of the mogas thru.

[Flyfalcons]

A friend of mine purchased a 182 that I was flying regularly and got the auto fuel STC. He said the engine became noticeably more cold-blooded with the auto fuel, and flying it with him made me agree with that assessment. So for whatever magical reason makes it happen, I do believe that there is a difference in the engine's behavior between 100LL and auto fuel.

[Kyle Boatright]

Originally Posted by Flyfalcons

A friend of mine purchased a 182 that I was flying regularly and got the auto fuel STC. He said the engine became noticeably more cold-blooded with the auto fuel, and flying it with him made me agree with that assessment. So for whatever magical reason makes it happen, I do believe that there is a difference in the engine's behavior between 100LL and auto fuel.

What did he mean by cold blooded? Auto fuel has a higher vapor pressure and theoretically should make it easier to start a cold engine compared to avgas.

[CPSONE]

Would be worth testing for alcohol content anyway...
http://www.eaa.org/autofuel/autogas/test_kit.asp
This is simply a Daansen 391S fuel ssample screwdriver available for around 5 bucks at most pilot shops.

Another note that's worth sharing;
I had a TIO-360 that started to be difficult to start and would quit at idle.
(Any engine behavioral changes from normal are absolutely worth investgating until you definitely know what the problem is.)
The problem...Leaky fuel primer solenoid. This darn thing sits on top of the engine and leaked fuel in that very undesireable location also.
It was leaking and as such sucked air into the system when running without priming I believe. In cruise it would barely be rich of peak with the mixture full rich. Blue staining was the way I found the problem. Cost of the part? Outrageous. Engine ran great after the fix.
I don't know a whole lot about auto fuel for airplanes but everyone knows that it can go stale just as avgas can. I recently overhauled a carb on a Honda generator and you should of seen the brown hard "calcium like" build up everywhere. The jet was completely plugged with this stuff, the float bowl coated. this was really old auto fuel though. Started first pull when I got it back together with everything cleaned out.
Good thread.

[Flyfalcons]

Originally Posted by Kyle Boatright

What did he mean by cold blooded? Auto fuel has a higher vapor pressure and theoretically should make it easier to start a cold engine compared to avgas.

Engine just didn't run well until it had a bit of warm up time.