Engine issue on takeoff.

I am guessing it was around 75 in the bubble. I remember taking my jacket off and I had the vents open during the taxi. The airplane was outside for around an hour with the canopy cover off before the flight. 

Thanks. 

I came from a medical background so a good chronological diagnostics is good to use. 

So food for thought,

So I believe that starting with the most common and cheapest diagnosis is best and easiest. So try switching fuel and see if it makes a difference and sometimes it does. If it does problem solved and it was cheap and easy fix. I believe starting and working in a chronological order and starting at A then B then C then D and so on. Follow an order so you don't miss something easy, common or take days to figure out when it could have taken a couple hours. If you bounce around from A to E then M and so on the problem may have been solved quickly at B and been easier.

p.s.

I don't always find it was just fuel, but as Rotax Owner stated the fuel needs to be ruled in or out and it's an uncomplicated test. There are other contributing factors at times to be considered. It could be an air flow issue (heat), and installation issue, an alteration issue and debris issue, ect.... Sometimes here on the forum we could use more info to help. For instance, I've seen several that thought it was fuel and it ended up carb bowl debri after a hose change, but they never popped the bowl off to check. Just one of those things to rule in or out as you diagnose.

If it was the easy fix with fuel then it's time to go fly and have fun. 😁 

Joseph, 

The one time I had a power loss (like you describe) was using winter gas on a spring day in CA.  It was probably only about 70 degrees outside, but I had stopped for a long lunch and the wing tanks were pointed right at the sun for several hours. The area of the wing over the tanks is painted dark blue, so they pick up solar heat quite efficiently. I won’t bore you with the details of steps I took to become convinced it was a fuel vapor problem, but one thing I did was install a fuel temp sensor along one of aluminum fuel lines at the fuel selector valve.  This sensor is still installed and integrated into my EFIS. It’s not uncommon to see fuel temps 90-110 deg f right out of the tank if the wings have been setting in direct sunlight, even when the outside air is much cooler.  On summer days I have seen the fuel temps of 115 deg f. in the tanks.  We get surprise warm and sunny winter days here in CA, so I never run winter fuel. When that is all that is available I mix it 50/50 with Avgas.  This time of year is exactly when mogas users can experience problems. 

I am curious; I run non-alcohol premium mogas. Does this non-alcohol fuel come in summer and winter grades like regular mogas?

James,

Funny you should mention that. When I had the problem I was using an alcohol free 92 UL. The distributor first claimed it was the same fuel he had been selling at our airport a few years back for LSA, which turned out to be wrong. This was before I could test the fuels RVP or even knew much about it, but a local flying group had it tested and found it was a very high RVP. I think 13 psi and this was in the summer.

Because we are in CA the fuel had to be sold for off-road use only so it was not subject to the summer/winter blending requirements. I called and questioned the distributor and he did some research and called me backs and said “don’t use this in your aircraft”. So your answer would depend on the regulations in the state you live. If it’s sold at the pump for use in cars, then there is probably a winter and summer blend. But if for off-road use only then it may not. I do know that it’s much cheaper to make a winter fuel because a lot of butane can be used and that is a cheap byproduct. You can easily test your fuels RVP with tools made at home. I think I posted that information a while back, but if you want it let me know and I will email it to you.