Andy Stemple

My Feedback: (11)

Okay, so I was flying my H9 yak with a Dl 50 in it. I was around full throttle and I went deadstick. Since this day I have not been able to get it to fire. I've checked just about everything and still haven't figured it out. I checked the ignition, spark plug, fuel lines, got new gas, completely cleaned out the carb and put in new diaphragm, fuel screen etc. The engine has popped maybe 5 times out of probably 500 flips of the prop, each time with the choke on. Any help or suggestions would be appreciated! I emailed DLE but they wouldn't help me because I have a DL [:@] Thanks!

w8ye

My Feedback: (16)

Either . . . .

The carb is closed

There's a crankase air leak

A damaged reed valve

Intermittant ignition

Blockage in fuel system

Minimal compression

Bad spark plug

BarracudaHockey

My Feedback: (11)

Fuel and fire and it should run. Are you seeing fuel move in the line? Have you grounded the plug to the case to see if its sparking?

What plug are you using?

pe reivers

A guy came to me the other day. His engine would just pop without starting. All was well or so it seemed.
It turned out he had made a new exhaust gasket, and forgot to cut the exhaust port area out!

Lesson learnt: always check the things that changed since the time it ran well.

Andy Stemple

My Feedback: (11)

Thanks for the input so far guys! The compression on the engine is great, just like new. I do see fuel moving in the line and I took the cover off of the diaphragm and there was a good amount of gas in there so it seems to be pumping. I'm using an NGK Cm-6 spark plug. I've checked to see if it is sparking and it is. Also the timing on the ignition appears to be correct. I've checked all fuel lines for leaks and they're good. Before the engine quit I hadn't changed anything, it had been running awesome for about a year. I will check the reed valves when I get a chance this week and let you know what I find!

w8ye

My Feedback: (16)

You can get a prelininary idea about the reed valve function before you take anything apart by . . . .

Opening the carb

listen at the carb opening while twisting the prop. As the piston starts up into the cylinder bore in either direction, the vacuum will suck the reed valves open. You will hear a click as they open and then some kind of escaping noise depending on how fast you are moving the piston. As the piston is descending in the bore, you should not hear anything in the carb?

After you remove the reed block you must try to sight through the mating surface of the reeds with a light on the other side.

Sometimes the reed block is distorted and sometimes the reeds will be frayed on a corner.

A distorted reed block can be flattened by rubbing the mating surfaces on a sheet of glass with some 400 grit sandpaper on the glass.

Valley View has DL50 specific parts but I think the DL50 and DL55 share the same reed block?

Bad reed seating will cause the carb to not pump well and if you do get fuel into the engine, it will just pop and never take off and run.

bcchi

We seen this twice in 30 years of working on engines,hard to believe.
Maybe it's like the guy who could not find top dead center because his engine was mounted inverted,LOL
BCCHI

jchorak

My Feedback: (9)

Same engine. Same symptoms. Had spark so started looking at everything else. Came full circle and replaced the ignition and now have a running engine.

JC

av8tor1977

My Feedback: (6)

I had an engine a while back that would just pop and quit when trying to start it cold. Sometimes it would run for a few seconds and then quit. If you kept at it, it would eventually run, and once warmed up, would start and run perfectly each time. I "tore my hair out" trouble shooting it, then happened to mention it to BCCHI. He said to try six volts on the ignition, as sometimes a weak ignition would cause these symptoms. Sure enough, with a 6 volt pack it would start perfectly cold. So I sent the ignition back and got a new one. (It was RCEXL)

AV8TOR

Andy Stemple

My Feedback: (11)

I've been out of town/ really busy so I haven't had too much time, but I did try a few things today. First I used a 6V battery on the ignition, still no luck. Second, I replaced the entire reed valve assembly. After I replaced this the engine popped a little more but still can't get it to run! I've pretty much given up on this engine now. Going to buy a DA or an evolution 58! Thanks for all of the input though!

3136

I would test the ignition and sensor.
This is a quote of JediJody
"Take an old expendable servo extension and cut off the male plug end, separate the wires, strip a bit of insulation from each of the 3 leads and plug the other end into the sensor lead on the ignition module.

Put a good spark plug in the cap, doesn't need to be all the way seated but far enough for the hex of the plug to make good contact with the metal shell of the plug cap, plug a fully charged 4 cell battery directly into the ignition.

Test for battery voltage at the red and black wires of the test extension you made and plugged into the sensor lead of the module, if there is no voltage replace the module, if there is battery voltage->

Short the white and black wires together, every time you break this connection there should be a spark, no or intermittent spark=bad module, has good spark->

Remove the test lead and plug the sensor on the engine into the module and turn the engine over, no spark, replace the sensor, good spark->

Remove the spark plug, look down into the plug cap and turn the engine over, if you see spark arcing through the silicone boot to the metal shell, replace the spark plug cap, no visible spark but you hear a snap->

Put a small screw driver into the bottom of the cap, turn the engine over and you should observe spark jumping from the screw driver to the plug cap shell outside of the silicone boot, an arc of about 1/4"-3/8", if it does this there is nothing wrong with the ignition, if you hear an arc but it's not in the cap with the screw driver, it could be a problem with the resistor in the cap or the high tension lead where it goes into the cap, replace the plug cap.

All of this can be done on a bench, the plug does not need to be grounded to the engine.

Good luck! "