MDS 40 engine Runs cuts out when plane is vertical

by Brian
(San Antonio,Tx)

Engine Runs great at idle and on level ground, But when you take the plane and tilt it 90* it cuts off...

This engine is a mds 40 glow engine/ Its about 2 yrs old and im currently running 15% fuel after. I was told the 10% was good for break in but once engine has broke in use 15-20%...

Any Ideas...

Just got into this hobby and have not had much luck with tuning this engine :(

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MDS 40 engine Runs cuts out when plane is vertical

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Mar 16, 2010
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aww man...
by: Matt

Glad to hear you figured out the problem with the engine.

Sorry to hear about your plane. But look the bright side, you are getting a new plane!

That's always what makes me feel better after a crash... Buying a new one!

Good luck to you, let us know how it goes...

Mar 15, 2010
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Figured out problem BUTTTT....
by: Anonymous

the issue was the needle valve seal, replaced it and engine ran PERFECT!!

Not even 4 min into this flight after rolls spins hammerheads the wings folded in at about 600ft so all I could do at that point was watch the plane crash down motor first, still has good compression spins well but broke the plastic that holds the needle valve on to the engine...

:/ oh well at least we figured out what the problem was in the event someone else has this issue...

what we did to fix it was cut a small 2mm size of fuel line and fit it over the needle valve and screw it back on...

the fuel would cut out if pointed vertical into the sky ran perfect when pointed down to ground...

checked fuel lines in the tank and all was well.. but this seemed to fix it and it ran flawless for 4-5min with no cut outs...

Thanks for the help, well try to get this put into another plane this week and give it another try in hopes nothing is damaged inside the motor, wont know that till later today when I can open it up and check parts...

Thanks again!!

Mar 13, 2010
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Vertical starving of fuel
by: Bill

In addition to all the good advice you received there is the possibility that the clunk has fallen forward and not falling back when you go vertical. Can you see the tank if you hold the plane in your hand as you tilt the plane horizontally and vertically?

Actually, the clunk line should not fold in on itself, it should have enough stiffness to stay in the fuel at all angles and yet flexible enough to stay where the fuel is. The length of the clunk line should be just short of the back of the tank when the plane is level.

Mar 12, 2010
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MDS 40 engine Runs cuts out when plane is vertical
by: Anonymous

rich it on main needle crying out for more fuel der

Mar 12, 2010
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90 degree Engine Stalls
by: Tehachapircflyer

Ok you state the the engine stalls at 90 Degrees. Well there are two 90 degree Directions. Is this with the engine facing the ground? Or facing the Sky?

If facing the ground then it would be the pickup in the tank is not falling forward and starving for fuel. And if facing the sky well then there isn't enough pressure to push the fuel upward against gravity to the carberator sounds like your tank may be the issue not the engine.

Make sure your tank is sealed with no leaks. The muffler pressurizes the tank and feeds the engine. On the ground it runs fine doesn't need as much pressure to push fuel to the carb.

Just my thoughts may be it is the engine but I'm thinking not. If it is then it would be a port timing issue and I wont even go into that.