Hello out there
I'm trying this larger forum than my usual, which is the Danish Modelflying forum, so I'm new here
I have just run in my second Saito FG20 - after having got it from my dealer as a replacement of my first FG20, with which I have one years troubles - not getting it to run satisfactory.
I'm a member of the biggest rc flying club in Denmark, and many of my fellow members with a lot of experience have helped me with the first engine before we gave up. Also the fuel installation in my Hangar 9 Funtana have been replaced totally without result.

The new engine was run in fine without problems installed at the Funtana, about 1 hour.
The first flight lasted for 14 minutes, and the engine run fine. After the first landing i taxied back to the start point, with the engine on idle a minute or two. Then, when I started for a new flight the engine died in 10 feets hight, about 5 seconds after I throttled up.

So now I'm back to exactly the same problems I had with my first FG20.

What I have not tried is to set the fuel tank under pressure - or to install a fuel pump.
Will that be a good idea - and can you put the tank under pressure from the muffler?

Thank You in advance

Welcome to RCU

The fuel pump in the FG20 carb is not very strong. The fuel tank needs to be close to the carb just as in a glow engine.

The tank is installed as close to the engine as i can be. The fuel tube from the tank is 5 inches - and the fuel tube in the tank is 4 inches.

Have anyone experience with an extra fuel pump to a Saito FG20 - and what brand?

Regards
Peter

It sounds like your fuel set up is OK. Make sure the fill line (if you have 3 lines) is airtight when closed. I had a problem with my FG-20 with the fuel line not being airtight and the resultant negative pressure in the tank was too much for the carby pump to overcome. I don't think it is worthwhile trying to pressurise the tank because this will only mask whatever the problem is.

Remove any inline fuel filters between the fuel tank and the carby to minimise resistance possible introduction of bubbles. You might also try running the engine with the plane upside down to see if this makes any difference to fuel delivery.

The other thing to try is to replace the spark plug. You might only get an hour or two running with the first spark plug due to the varied running conditions with initial tuning. You can use a cheaper after-market plug rather than the expensive Saito brand.

I have the Saito FG-14 and FG-20 which are running well. When I have had problems it has been because the spark plug is nearly worn out or my fueling setup has had a problem. Sometimes it is a simple thing like the clunk tube falling off, the fuel bottle stopper not being tight enough, or a small split in one of the lines. Always keep the fuel/vent/fill lines with these engines as short and simple as possible. </p>

Thanks w8ye and MercerAUST for answering
I have mounted a seperate fill line with a filling valve of the same reason: To prevent false air to sneek into the feeding line.
Also I have removed the filter last time I changed the tubes and the clunk in the tank.

The 'plug' solution is worth trying - and mybe I should turn the idleneedle 1/4 to a richer mix. One thing at a time?
But how are the carburettors on bigger gas engines fed? is'nt it with separate electric pumps?

Regards Peter

The FG-20 has an inhouse Saito carby (rather than a Walbro) that uses some sort of membrane pressure. The result is that is can't transfer fuel over much of a distance. 20cm is probably about as far as you can do assuming the carby is roughly at mid-tank level (eg not pumping uphill).

I'm using black fuel tubing so I can't see if the fuel is flowing or not, but experience has taught me that ifthe engine has been running fine and then drops off, try a new spark plug first and then check the fuel set-up.

As you know, the engine is fiddly to tune and even a few clicks can make a huge difference. The low needle influences most of the throttle range. I generally find it best to run the low end a little rich, which then enables the high end to be leaned out 4 or 5 clicks more. Of course, too lean (top end) or too rich (low end) and the engine will usually die at the worst time (eg WOT on take off). I found the best way to tune (both low end and high end) was to hold the plane up to the sky and tune each needle accordingly at idle and WOT (engine dies it is too lean, engine splutters too rich).

I currently have my FG-20 in a VQ 2.7m wing span Pilatus Porter (6.5kg total weight). It ran perfectly, but I changed the fueling set up and it took me ages to get it right. I must have dug the fuel tank out of the belly of the plane about 4 times to check/replace and check things again and again. I had a succession of small problems (all adding up in difficulty in getting a good flow of fuel to the engine) which I finally fixed up. I've had the equivalent of about 5 hours good engine operation since that time. The engine economy is amazing (about 1 hours flying from 500ml of petrol).

My experience so far with a plane I picked up recently that had a extreme low time Saito FG-20 was right inline with most of the problems talked about on the forums. My engine even still has the original carb. Call me stubborn, but I went to work to see if I could get the engine to run correctly. I pulled the engine from the plane to install it on the stand and the first thing that I discovered on the very first run on the stand was studder in the engine if I moved the ignition module. After some investigation I discovered an error from the factory in the crimping of the wires onto the pins in the plug of the pickup. After correcting that problem the engine studder cleared up, but the midrange still needed work. It took me two things to fix this problem. One I installed fuel barbs & zip ties on all the tank lines inside and out. Secondly I played sound with the tank placement as MercerAUST did above and now the engine is running great in all the flight conditions in the plane. I must admit that I was worried after reading some of the horror stories, but you just have to ensure that the fuel system is tight, the module plugs are crimped correctly and that you get the fuel tank placement right.

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