Greg Cothern

My Feedback: (8)

My ZDZ twin 80 just quit in flight as if she ran out of gas or you shut the ignition off. Back at the pits couldnt get her to run at all. I checked the ignition battery & switch both were just fine, checked to see if I had spark at the plug and yes. Had plenty of fuel in the tank, so I pulled the spark plugs and they were a nice and golden brown as one would expect, but no sign of fuel on them as if the ignition would have signed off during flight. So I am assuming this means a fuel related problem, I pulled the fuel filter and cleaned it. Pulled the tank and cleaned it as well. Everything checks out ok. I go back through my routine of firing up this beast, full choke, 1/4-1/2 throttle, and ignition on, flip till she burps. And she does, I think hey she is going to fire up now, so I take choke off, pull throttle back to a high idle. Well after more flips than I care to count and my arm is now tired, she will only burp again, and when she does this it spins backwards as if the timing is way advanced. So I check the timing adjustment, I pull a plug and get the piston to TDC and set the halls sensor to approx 6mm behind the magnet, as shown on the following site:http: //www.zdz-motor.de/falkoneng/lokal/html/installs.html
She still will not fire up and run, I am at a loss as to why this thing will not start up and run. She has not missed a beat until now. Thanks for any help you can provide.

tkg

My Feedback: (1)

Prime it by dribbling gas down the carb. Then try to start it. If it runs for a few seconds and quits you have a fuel problem. If it still won't run you have an ignition problem.

Greg Cothern

My Feedback: (8)

Tkg, that is a very good suggestion, but with the ZDZ twin the carb is horizontal inline with the crankshaft just behind the firewall. Makes it just a tad hard to poor fuel in, LoL. I may have to pull it and make a engine stand for her then I could do as you suggested, thanks.

captinjohn

Get a primer assy off a weed wip or simular engine. You can use the primer to shoot a little squirt of gas into the carb with plane in a nose down attitude. It helps to have the throttle wide open when doing this. Make sure to return to normal idle before you start. Thanks John

Lew

The carb on my 80 single - the inlet valve stuck open - maybe yours stuck closed. Open it up and see if it will move up and down. After I worked mine a few times, it has worked flawless. Good luck

Lew

rmh

Which ignition module are you running -also what voltage batt on the ignition.
Some of the earlier modules would develop an internal path to ground - they "check out" good but don't fire under compression.
It's hard to troubleshoot an engine over the air -but assuming that engine is drawing fuel - isn't flooded -I would suspect ignition related problem.
IF your ignition is other than newest type blue label FALKON- I would suspect the grounding problem.

Greg Cothern

My Feedback: (8)

Dick, I am not sure off the top of my head which module is on this one (I am @ work, I will check it though). I am running a 4.8 pack on the Ignition and had a fully charged pack in the 5.4 range.
I think I forgot to mention that everytime I check the spark plugs they are completely dry, never wet at all or any sign of being wet. I feel that it is a fuel delivery problem. If the ignition were the cause then wouldnt the plugs be wet due to them not firing? I think something may have stopped up a passage in the carb. Anyone know how the rotary disc is attached to the crankshaft? Could it have possible rotated out of time??? Thanks again for all your help and suggestions.

rmh

The disc is driven by a nub on the crankshaft-
Fuel delivery should be quite easy to figure out - The ignition part is not easy -unless you have some ignition background - that is why I mentioned it.

Forgues Research

My Feedback: (7)

If you can't reach the carb inside the Fuselage, (the reason for the standoff's) remove the plugs, put a bit a gas in directly in the cylinders and try again,, but your last E-mail is proving a fuel problem. When you choke, make sure the choke plate is fully closed. It happened to me at a flyin. When I got home, try the choke plate and sure enough it wasn't closing properly, fixed it via the TX (I use a choke servo) and VOILA, worked fine after that.

Greg Cothern

My Feedback: (8)

Dick, I checked I have a gold or yellowish labeled ignition.
Roger, I do have a servo operated choke and I did check to make sure it was closing all the way.
I am going to pull the carb and get after it with a air nozzle to see if there is something clogging up somewhere.
Thanks for all your help and suggestions, keep em coming just in case the carb is not the prob.

Forgues Research

My Feedback: (7)

Your ignition module is the right one, the blue for singles and gold for twins.

rmteo1

My Feedback: (2)

I'm not sure if your interpretation of the ignition color coding is correct. I have 2 ZDZ singles, a 40 and an 80. The ignition on the 40 is gold colored and the one on the 80 is blue.

rmh

The new twin ones are blue - 2.3 Falkons-

Texan

My Feedback: (10)

Greg,
You may have picked up some contamination in your fuel that is clogging the filter screen inside the carb. Are you using any inline fuel filters?

OUTCAST

Make sure the carb and intake is tight with no vaccume leaks. You said it will pop with the choke on so we know the plugs are firing, I would look to fuel/air for the problem.

Greg Cothern

My Feedback: (8)

I do have a inline fuel filter in place between the tank and the carb. When I pulled that tank, filter, and carb to check and clean, there was some of what appears to be silicone ATV present in the tank and the filter (the gentleman I bought the bird from apparently used it to help seal the tank stopper). But when I opened the carb there was no sign of any contaminents in the filter screen in the carb and the diaphram looks pristine. But a small piece must have made its way into a passage way, I cant find any other reason for the problem. I am going to soak the carb housing and blow out with a air compressor and reassemble to see if this will be the cure.

Greg Cothern

My Feedback: (8)

Ok well back to the drawing board. I pulled the carb and took completely apart and cleaned out, to no avail. She will only burp on full choke, and the same with choke off and I have to flip with everything I have to get a fast spin to get even a burp. I even used a syringe and put a small amount of fuel into the cylinders and tried, she just burped again. I checked and rechecked the Halls sensor to make sure I do in fact have it set appropriately and I do.
Dick, can the rotary valve in fact spin or is it cammed or such so that it will not? It has to be either this or the ignition as you previously stated. But again I keep coming back to the fact that the plugs are always dry and never wet with fuel after many feverish flip attempts to start. This is why I continue to think it is a fuel delivery problem. Help I am very discouraged in DFW.

Divesplat

My Feedback: (7)

It sounds like there is an air leak between the carb and the cylinders. On my engines, I put a very small amount of car engine RTV between the carb, phenolic plate and reed valves. Worked like a charm after that. This wasn't on a ZDZ though. The leak is typically soo small that you won't notice it visually.

Worth a try after everything else.

Ed

captinjohn

Get some starting fluid from just about any atomotive parts place or Wallmart. If adjustments got off this starting fluid will help that burp into a power stroke and it may then start. Adjust carb after it starts. This starting fluid says it has upper cylinder lube good for all engines. Hope this helps. Captin John

Diablo-RCU

My Feedback: (1)

You can also use a shot of WD-40 as an engine prime. If the engine runs for a second on the WD-40, then you know the problem is fuel starvation.

If you have a weak ignition, sometimes you can get them to fire by closing the plug gap down to about .018". A smaller gap requires less voltage to jump.

smolensk

Sounds to me like you have an ignition module failure.

Greg Cothern

My Feedback: (8)

Hmmm all good advice, the needles should not be out as I was in mid-flight when she quit. She has run flawlessly until this episode.
The plugs are gapped @ .018-.020 and I have great voltage going to the ignition (5.4v out of a 4.8 pack).
I keep coming back to the fact that the plugs are dry and not wet with fuel, and this would suggest a fuel delivery problem.
There is a gent in our club that has a "godzilla" starter (a car starter that has been adapted that would turn over a tank engine), I am going to see if I can "spin" her up with authority to see if she will come to life.
Still baffled. Thanks for all your suggestions.

T-ster

I've been through my share of Vlach/Falkon ignitions. Try a new ignition module. That may do the trick.

captinjohn

I think getting the engine and putting a ch on it would be the trick. Or even just as good or better -a RCIGN system. Somebody will do it as soon as they get sick of playing around with the stock ones. My 2 cents Captinjohn

gizmo8012

My Feedback: (15)

my zdz80 single did the same thing when I first tried to start it after I bought it from a modeler, I tried and fought with it till I decided to send it in to rcshowcase for repair, thought it couldnt hurt, anyway I got it back and it now runs flawless and starts after a couple of flips, Mike Dooley said that the butterfly was opening and closing in the wrong direction it should be closing on the left of the carb facing the rear of the engine and opening to the right, that did the trick, you might want to make sure your throttle adjustment didnt move or come loss in flight, just a thought though. later.