The problem I am experiencing is this, I have about six flights that I have put on the engine (3W150 old style, previous owner had a lot more on it) with brand new 3W ignition. I have had two dead sticks out of the six flights the other day. It seems that I can fly right up to around nine minute flights without any problem what so ever but as soon as I hit nine minutes the engine just dies. There is plenty of fuel, I am thinking it is a heat issue. The engine is mounted in a 40% Carden Cap 232 with a 32X10 Bolly Carbon prop. The cylinder head temp was 268* with no baffling immediately after shut off on my last flight which was not a dead stick. I plan to install some baffles on the cowl intakes and see if it helps before any further flights.

UPDATE

I installed baffles in the cowl per the Cactus Avation website. The temp went from 268* to between 185* and 200* but I am still having a deadstick problem. Two out of four flights today were deadstick. I no longer think the problem is heat related and today it actually happened about five minutes into the flight instead of nine minutes. I am thinking it might be a fuel delivery problem of some kind. The engine drops down to an idle and sputters before it finally dies. I pulled the tank and the lines and tank look clean. I am wondering if it might be a problem in the carb? Any thoughts anyone might have or advice you could give would be greatly appreciated.

I replaced all the fuel lines tonight. I noticed after the last dead stick that there was an air bubble in the line where the t-fitting for the refuel line connects. I got rid of the t-fitting and ran three separate lines.

I pulled the top half of the cowl off and looked at the plugs. The metal ring part of the plug is a dark grey or black and the electrode was a white color so I will also try richening the screws a little.

Have you checked your battery voltage when you land? I'm curious as to what it's reading. What kind of battery are you using?

Battery is a Fromeco Lithium Ion pack 7.4 volts with regulator (2400 mah pack regulated to 5.1 volts). Voltage before the regulator under one amp load is 7.84 volts, 5.1 volts to the ignition according to Cactus Avation this is fine. Thinking of bumping the voltage up to 6 volts at the regulator Cactus Avation says it will take 6 volts ok but no more.

Battery is a Fromeco Lithium Ion pack 7.4 volts with regulator (2400 mah pack regulated to 5.1 volts). Voltage before the regulator under one amp load is 7.84 volts, 5.1 volts to the ignition according to Cactus Avation this is fine. Thinking of bumping the voltage up to 6 volts at the regulator Cactus Avation says it will take 6 volts ok but no more.

Swat,

My guess is your new fuel lines will do the trick. It sounded to me like you had a stiff clunk line. Also, you're smart in dumping the tee and going with the 3 line system. You're also correct by looking at your plugs and making the proper needle adjustments. I think you're on track in diagnosing your problem. Good luck. If this doesn't work move onto the carb block to check for leakage there. You 'should' be able to make your engine run rich just to verify that you're not sucking some air somewhere.

Rich

The clunk line was flexable but I spoke to Bobby at Cactus Avation and he thinks it might be a pinhole in the clunk line somewhere. If this doesn't do the trick I will take your advice and move on to the carb block to look for a problem. Thanks.

I agree it sounds like a broke clunk line, It might have a crack where the brass tube ends.

Here are two things you might look at if you think it's a fuel issue and nothing else helps.

Have you checked the filter screen in the carb? Not sure which make or model carb you have. Most likely it's a Tillotson.

When my old 140 was leaning out in flight, I bit the bullet and learned about what is called "pop off pressure" for the carb.
Turns out mine was set too high, and the fuel inlet needle wasn't letting enough fuel through. The concept took me awhile to grasp, but I'm glad I took the time to do the research.

Try a search, and look at this link. [link=http://www.rcuniverse.com/forum/m_1866098/anchors_1866098/mpage_1/key_pop/anchor/tm.htm#1866098]pop off[/link]

Hope this doesn't turn into a Ford_Chevy thing

Lots of machines have trouble from time to time and need attention. Granted, the newer technology carb blocks don't have the bad tendencies of the older designs, but they still work when they're flat etc.

Anyway, poke around and keep us posted on the results_bob

Well, I replaced all the fuel lines from the clunk to the carb, got rid of the T- fitting, checked the plugs and gaps, bumped the voltage regulator up to 6 volts, and richened the high and low needles just slightly. The engine ran grat today.........for exactly eight minutes until it went deadstick again. I think that makes like six deadsticks on this plane.[:@] I think I might just try buying a whole new carb. Open to any other suggestions.

Swat,

I know this sounds dumb, but are you absolutely sure your vent line isn't pinched off? Are you capping your vent line after fueling?

Wow that is frustrating. You did everything we all would have done. I an not sure why you changed the ign voltage however, 5.1 v is fine for that pack.

You still might have an ignition problem, it is possible that the circuitry is sensitive to heat and after some buildup it cuts out. I have seen this once in a CH module, we chased a fuel problem for days and when we swapped modules the problem was fixed. The new 3W ignition is pretty rock solid however.

I find it hard to believe its a carb problem since the engine runs fine at full tank BUT I have seen some screw problems with those tillotson carbs from time to time. When the tank is full there is no air and at least some gravity feed. If the pump diaphragm is weak it may not be pumping correctly when the fuel level drops. Any time I had one of those carbs act up I put on a Wallbro - same one that's on the DA. Problem fixed.

I normally don't recommend this, but you might want to ground run it for that amount of time and see if it still happens. This would confirm the ignition and probably rule out the carb. Keep and eye on the heat buildup though.

Stinks to have to do this but you might want to send the engine in for a checkout. Dead sticking that plane at the wrong time could be really costly.

DP

yeah, it may sound dumb, but it sure sounds like a pinched vent line. easiest enough to check - the tank will look like it imploded. i don't think it is a carb problem. but for fun, i would try a different fuel supply (on the ground) and see what happens. sure sounds like the tank is draining about halfway, and then not drawing fuel - i would suspect some kind of crack or leak in the tank carb line - including the brass tube. another thing worth trying - with a friend - is to fire her up, and then hold the airplane vertical and advance the throttle. if it dies fairly soon, that's a pretty good indicator that you have a fuel draw problem. oh yeah, the other possibility is that fuel lines are reversed. we have all done it...

P

I think I may have found the problem. I pulled the cowl and noticed the back of the engine and carb spacer was wet looking. I wiped it off and smelled it and it wasn't gas so that means its from the crank case. I pulled the carb, carb spacer and found that was the source of the leak (right at the hole for the crank case pressure that actuates the fuel pump). I don't kow why this would cause a problem after eight minutes of flying though.

I was thinking that was the problem until I read the post from planeinsane and paulBK. I just realized the problem seemed to have started right around the time I put the smoke system on the plane. Guess where the smoke tank sits, right over top of both tank vent lines. The tank is not imploded at all but I bet tomorrow when I remove the smoke tank the problem will be fixed. I will let you know tomorrow, thanks for the input.

Oh, one other thing I checked the temp of the ignition box inside the engine box after the deadstick and it was 92* so I don't think that was the problem.

Just went out to the garage and checked the fuel vent line and its definately NOT kinked. That was a great idea though.

Damn! Just got back from the field and same old S**t. This engine is really trying my patience. It seems to slowly get leaner and leaner until it quits.[:@]

If it were me, I would either commit to having the engine serviced, or stop flying it.
Eventually, in the back of your mind will always be the thought of the engine quitting.
At that point it just isn't fun anymore, and you're flying with anxiety.

A quick and easy determination of a carb problem would be to simply try another carb. I know it's easier said than done, but other than sending the motor in, you're guessing, and compromising the airplane.

I don't remember, what is the condition of your carb block?

Also, there were some 3W castings that developed cracks if I remember correctly.

I own three 3W's and am not degrading them in any way. Like I said earlier in this post,
at some point most machines need some kind of service or attention.

All three of my engines run great and I like them alot.

With the proper attention, yours will too.

It's got to be one of the big three.
Fuel - Air - or Fire

Good luck_bob

Its not the box temp that matters, it could be a component on the circuit board inside that heats up and shuts it down - its a remote chance but it could be happening.

I would seriously try a ground run with a good strong partner that can hold the plane. Do it off the field so everyone won't yell at ya for making noise! Run it like you fly it.

I have seen new ignitions be bad out of the box.. you might as well rule it out before sending the engine in or tearing into the carb.

I would be pulling my hair out if that was my engine.. I went through a lot of crap with a DA100 recently. I finally found out it was a pinhole in the fuel line right AT the carb inlet .. we found it AFTER the engine was take off and it bench ran perfectly.

The DA ran flawlessly at high speed on the plane but we never were able to get it to idle down... air in the fuel lines will do it every time. There is no way we would have caught it while running because the leak was just prior to entry into the carb. The reason we did catch it is we changed out the line when the engine came back... while looking at the end, I noticed the hole! It probably got tweaked with the needle nose when we pushed the line on!

The wierd thing about this problem is that it only did it at idle. You would think it would have been the other way around!

DP

I just found this thread (carb block problem)

http://www.rcuniverse.com/forum/m_12...tm.htm#1258791

and think that may be the problem but I am not positive so I think I will just bite the bullet and send it in for service. Hopefully they will be able to solve the problem.

Who will you send it to?

yea, I guess.

Hey Kevin,

Not for nuthin, but go to post #2 in this thread. Maybe it's worth trying a nicad, just for grins and giggles. When he started talking about 7 minutes flights and then a deadstick, well, you check it out and see what you think.

[link=http://www.rcuniverse.com/forum/Ignition_Battery%2C_Li%2Dion_or_NiMH_%3F/m_2677039/tm.htm]deadstick[/link]

Bob nj, I wish I would have seen your post yesterday. I just pulled the engine off the plane last night. That thread you pointed out sounds EXACTLY like my problem and I have tried everything else. I think I will put the engine back in the plane this afternoon and try it with a nicad. If I don't and I send it in for service, they are probably going to hook it to a nicad and if it works fine in the shop I will be back to square one hunting for the "Ghost" again.

Stay with it, and keep your head up

Swat
If you check out a thread called aertoech 35% edge build you will find Sweet had some problems with his engine. I believe it is a 100 though, but he had some running problems, not quite like yours but it would not run on the lithium he had on it. Just a thought as well.

Mat