My enginge is cutting out at full throttle....any help?...thanks

You haven't given us a lot of details so it's rather hard to understand the situation and give meaningful advice... []

However; this is the beginners forum so I can make some assumptions...

When a engine "Cuts out at Full Throttle." , the usual culprit is the pilot that tuned the engine too lean. [&o]

A new pilot usually has a new engine that is not properly broken in, and the pilot is too green to know what that means.

So what you have probably done is tuned the engine for the highest possible RPM and then went flying.

Once in the air the engine "UNLOADED" (with the AC in motion the engine had less resistance and went even faster!), now the engine is going TOO FAST [X(] and the oil in the fuel is not keeping the engine cool enough so the metal on metal of the engine over heats, expands and then siezes (binds) which means that the engine stops and you now have a glider... [:@]

The Solution; tune the engine for 1-2,000 rpm less than max, allow the engine to break in for 1- 2- gallons of fuel and then retune for a higher performance.

This is a common fault and solution for newbies.

engine is not new...has aready been properly broken in as per manufactuers instuctions...not running too lean....cuts out at full throttle

Does it just miss a beat, slow down, quit entirely?
Are there ari bubbles in the fule lines, foaming in the tank, holes in the lines, tank pressurized?
Does it do it on the gound and/or in the air?
Does it matter if the nose of the plane is high or low?
Is there a kink in the klunk line in the tank due to a sudden stop landing which caused the clunk to flip forward.
What kind of engine is it? What prop? Tank pressurized?
What kind of plane is it in?
Did it ever run properly in the present installation? What (if anything) was changed?
Have you changed the glow plug?
Are you sure the fuel is fresh/OK/ suitable?
Is there an in-line filter? Is it dirty/obstructing fuel flow?

Lots of questions but you haven't told us much yet to start with.

Oh yeah, is it too rich?

Engine is a MDS .40 FS-1 Pro,prop is 10x7,Plane is a Hangar 9 Xtra Easy.Plane was bought used...never flown by me so the engine problem only has been on the ground.I have not replaced the glow plug or done anything else to the engine other than fueling it and starting it.I have seen tiny buules in fuel line,and carb is not foaming but there is fuel visible sometimes,In the carb opening that is.

Try changing the glow plug and balance the prop. It may be causing air bubbles from vibration.

Rod

Change out the fuel lines all the way from the "clunk" inside the tank, to the carb.
A tiny hole in a line will definately cause an engine to run "eratic" or not at all!

It is surprising how often a fuel line gets a "knick" inside the tank and this will ruin performance, especially after some (about half) the fuel is burned up.

I would suggest trying a new plug first. Based also upon your previous thread, I still believe you may be too rich at top end. No insult intended but are you experienced at tuning engines? You say there is fuel visable in the carb opening sometimes. What does that mean?
Fuel puddling?
Fuel spray with the engine running?
Fuel spitting back out?

Yes Bruce ,I am new to tuning engines....trying to learn by asking questions.What I mean by fuel in the carb opening is when i slowly open the throttle i can see and hear fuel around carb opening...I have needles set as manual says and am trying to go from there to get it tuned correctly...

Hi!
Are you sure you don't run the engine too lean?? Factory settings are just a way of getting an approximate setting ...not a way of obtaining a GOOD setting!
You have to listening to how the engine sounds at full trottle and set the high speed needle a little rich. Then hold the model straight up and check the rpm. It's vital that you always run your engines a little rich in this position.
A much better prop thanm a 10x7 would be a 10x6 or 11x5 APC.

HI! yes i know factory settings are just an approximate,it's a starting point for me.When I get it running as close to correct as I can I will be sure and hold the model straight up.And yes I have learned to run it alittle rich by reading forums.


Manufactuer suggests a 10X7 for "break in".....I was going to get a 10X6?

So OK, you're saying that when you advance the throttle from idle to max it accelerate OK but as it get to max it quits.

Does it run in a high pitch 2 cycle before quitting or does it sort of "blubber"?

If you hold it a little short of full power will it continue to run? If so, try opening or closing the needle valve by just a couple of clicks and see if you can get closer to full RPM then. If not, turn it the other way and try again.
Repeat until full RPM is available.
At full RPM you want to be able to pinch to fuel line (watch out for prop) just before where it enters the carb and have the engine accerate briefly and die of fuel starvation. That tells you it is running at just about the correct leaning point. If, when you pinch the line, the engine just dies w/o accelerating it is too lean.

Yes I did the pinch test.....think I got it about right....When it was cutting out it was at hi pitch all the way up to full throttle,then it just quit...also I noticed...when I was getting excess fuell at carb...engine was running wrong way....i.e....prop blowing forward.I started it ccw......shut it down...restarted and it was ok.....was the prop reversing when i started?...I'm learning so bear with me.

Don't worry...we all went through the learning process..or should I say are going through it? Hang in there and ask if you don't know. It's the way to learn! There is nothing wrong with being a beginner.

Rod [sm=thumbs_up.gif]

There is more of a tendency for an engine to start backward when hand starting than when using an electric starter. An engine that is running in reverse should not be run to full power and will usually refuse to do so and may actually damage itself doing so. There is usually no damage if an engine starts and runs in reverse briefly at slow speeds. Sometimes an engine will reverse after the start if it backfires for some reason.

well i think that was my problem,I am useing a chicken stick to start it.When it it running in right direction it is fine

Try fuel from another jug, youirs cold be wet.