dingo9882

I am having a problem with my FL-70 O.S. engine. But, I am not sure if it is the engine or the gas tank. While flying my sig 4 star 40 it runs great, but as soon as I try to do a loop or something like a cuban 8 it stalls out on me, making me dead stick it in. It has done this to me almost every one of my flights. It is broken in and everything. I read the manual and it told me to set up the fuel tank for aerobatic manuvers, so I did. I put the third line in the tank and put another three way into the lines as shown in the manual. It got a little better but it stalls out on me still. This is driving me crazy. Can anybody help me with this problem? Are there any alternatives that I need to do to allow it to work properly? Could it be the third copper line pointing down into the take be too far into it, or too close to the opening of the tank?

bubbagates

My Feedback: (32)

I am a little confused though about the 3-way you are refering to. I had that plane 2 years ago and I cannot remember anything regarding a 3 way setup. If you are refering to a 3 line setup it is really not needed for that plane as you should be able to get to the fuel line where it connects to the carb pretty easily.

The first question I have it does it happen once inverted or on the upline when doing the loop.

If it's the upline, then I would suspect the needles are set too lean

If it's happening while inverted, I'd verify the fuel pickup clunk if free to move. If you hold the tank with the stopper facing up is the fuel pickup clunk close to the back but not touching it. If you hold the tank inverted, does the clunk drop to what is now the top of the tank freely

If it is a 3 line setup then also make sure you 3rd line is not interfering with the fuel pickup line. On my 3 line setups I make the fuel pick and the fuel filler line the same length with the same clunk then I will use a wire tie to hold them togther so the do not wrap around each other and move freely within the tank but I do not tighten the wire tie tight enough to pinch the liines

dingo9882

The engine is quiting on the down decent. Going up its fine. It climbs great actually, but when it comes done like at the bottom of a loop it stalls on me. I checked the clunk and it moves freely within the tank.

bbbair

To me; it sounds like you are running the engine too lean. [:'(]

Richen the high end needle 2-3 clicks and see how it works. [8D]

The other answer would be that you have a pin hole in the fuel lines (some where) and you are sucking in air... richen the high end before you go chasing ghosts...

redfox435cat

this is usually caused by thress things. bad tank position, sound like its right though I don't really like the 3 line set up. keep it simple. That just me though. second is a lean high end. set the needle for peak RPM then back it off 300-500 RPM. I recommed doing this with a tach. I can a pitch change in 2 strokes just fine but 4 stroke I have a problem readlly haring the change. last and what sound like the problem isthe idle screw adjustment. If the idle screw is not adjust right it will suck air at full throttle and usually manifest itself in steep climbs and decents. just a though

I like doing the line pinch method for the low needle. set the motor to idle and pinch the line for a few seconds. if the motor surgest and stops it's rich. if it just stops its lean. re adjust until pintch has little effect. re adjust the high end and recheck the low end.
Most 4-stroke or any engine for that matter come from the factory with a rich idle setting for breck in. Surprisingly few adjust it after a motor is broke in