BME 50 won't run.
 

I have a new BME 50 that has 20 oz. of fuel through it. I flew it set rich the first flight then began to lean it out on the second flight. Everything worked great. I went to start the engine for another run and now it pops with the choke on, turn the choke off and it runs lean for a second and dies. So I figure it's not getting enough fuel. I first checked my tank to make sure everything worked correctly and everything checks out there. If I blow through the vent tube gas comes out the pick up line no problem. I decided to open the high end needle, no joy. Opened the low end needle, still no joy. I took the entire carburetor apart to check for debris and found none. I have been running a micro screen type filter on the pick up line so I would be shocked if any debris got it that way. I did put everything back in it's original configuration on the carb so I don't think that's it. I also have other gas engines so I am familiar with them but this has got me stumped. I checked my ignition battery and it checks good. I am about ready to run a separate gas tank to completely eliminate that possibility and go from there. Anyone have any other ideas?

BME 50 won't run.
 

I had similar problems on a gas engine that was sucking large quantities of air through a pin hole in my gas line filter. Are you sure your lines are good? Also, a freind had similar problems caused by his spark plug gap set way to small. The spark was too weak and the plug just got wet and fouled. When we opened up the gap to the recommended setting, the engine purred like a kitten with fresh milk! :)

Good luck!

BME 50 won't run.
 

Looks like a common problem with the BME50. Mine ran perfectly for a few gallons then started giving me fits like you describe. I tried everything with no luck. At this point I'm pretty confident that it's sucking air somewhere. Either the carb spacer area or the crankcase seals. I haven't tried to fix it yet, but you might start looking at an air leak somewhere on the engine.

Ben

BME 50 won't run.
 

Thank you very much for the suggestions. On the fuel lines I would be very shocked if there was a pin hole. If there is a pin hole, how did it get there on brand new lines which worked fine on my first two flights??? But I have not completely eliminated that possiblility so I will isolate with separate tank and fuel lines. As for the spark plug my gap is set at 0.022 - 0.023 inches. It was at 0.025 and I reduced it slightly to see if that would help but it didn't.

BME 50 won't run.
 

bdphil, I hope your wrong. That would not be a good thing. But there is a solution to every problem and I'm sure we will come up with something. I have no other plane at present so I am very motivated to get it working. If it is something in the carb can I put the carb from my brison 3.2 on it to check that portion out?

BME 50 won't run.
 

Seems narrow. The recommended gap for the ZDZ50 is 0.035. It was at 0.025 from the distributer and it ran like crap till we opened it up. The pin hole in my setup was in the filter it self. Easy to see when choking the engine. You can see the air in the lines. It however takes a large amount of air to bother a Walbro carb.

Have you checked for a good spark? Timing?

Good luck! Hope you figure it out.

BME 50 won't run.
 

I'll try to increase the gap a tad but I'll be amazed if that's it. There is a small amount of air in the line by the filter so this may be where my problem is too so I'll just by pass it temporarily. I have to go to work now. Damn.

BME 50 won't run.
 

The spark is not the problem here since tries to start when choked and runs for a short one second. The problem is it can't draw any fuel either because there is an air leak in the engine or carburetor or something blocking the fuel jet. I have bypassed my fuel system completely so that is not it. The best I can do is take my carb apart again but I really don't know where to look. This thing looks real clean inside. It really seems to me like a small speck of aluminum from the engine itself is blocking an orifice somewhere I just don't know where though. Any ideas where I can look. This really bites since it stopped raining now I can't go flying.

BME 50 won't run.
 

You might want to remove the needles and see if any debris from the manufacturing process is behind one. If there was and you turned them all the way in to adjust , it may be lodged at the orifice.

Also, does it ever backfire or not start at all?

BME 50 won't run.
 

I am now at wits end with this engine and am afraid I will have to return it to BME for repair. I have examined every part of the carburetor except the small jets behind the Welsh plug. I have no idea how to get that out to look at it. All other orifices are clear. I cannot conceive how this is happening but it is. The other thing that is strange is when I put the choke on it won't draw fuel through the line as I turn the prop over. As soon as I put my thumb over the air intake the fuel shoots right up to the carb no problem. Since I can't see any obstructions in the orifices I am now beginning to think there is a major air leak somewhere. But where are the failure points on this engine? This is starting to piss me off cause how can the thing run great two times and on the third flight develop a major air leak? Any one else having this kind of trouble? :mad:

BME 50 won't run.
 

A Walbro carb that won't draw fuel has a leak somewhere between the cylinder pulse hole and the carb body..If there are no leaks or restrictions the carb will pump fuel at least 4 feet straight up....Take the back cover (one screw) off and crank the engine, you should be able to feel a small pulse at the hole near the base of the carb..Be sure the diaphragm is against the carb body with the gasket on top..On the other side (4 screws) the gasket goes against the carb with the diaphragm on top..The inlet needle lever on that side should be flush with the floor of the cavity right next to the lever....Spark gap has no effect on the running of the engine unless it's too small.....

BME 50 won't run.
 

Is this your first gasser, and what initial settings are you using on the needles?

BME 50 won't run.
 

Ok, I'll try that. What if I get no pulse?

BME 50 won't run.
 

Tailheavy,

I feel your pain. I struggled with my BME50 for a few months and tried everything to get it running right. I finally broke down and replaced the engine so I could fly my 29% Edge. It sounds like your're having the exact problem that I have with mine, but I'm sorry to say that I haven't found the cure yet.

I started a thread about the problem a few weeks ago under "BME 50 can't get right". I don't know how to post a link to it, but I got alot of suggestions that might be of some help to you.

I'm gonna try a few things with mine, hopefully today, and I'll let you know if I come up with anything.

Ben

BME 50 won't run.
 

No this is not my first gasser. I do have a good general idea how the engines work. I just never had a problem like this stump me this badly. The needle settings are irrelevant as the problem persists even with the needles removed! There is no visible sign of debri that I can see but like I said there some areas that are hard to examine without removing the Welch plug.

I am going to try RCIGN1's idea to check the pulse and then report back.

BME 50 won't run.
 

bdphil, I will return the engie to bme if I have to but I am real upset about the whole thing. I know there is reason for it acting like it does and I want to know why. I sure wish I had another carb to strap on to eliminate that at least.

BME 50 won't run.
 

I had a frined who I sold my BME 44. Well he had a minor crash and had to take the engine off the plane, but when he did this he removed the carb to check for trash and when putting the engine back together he put the pulse line on the carb fuel inlet. Choked it would pop but would not run. Switched lines to the proper place and no more problem.

I hope this isn't your problem but it's possible. If I were you I would call BME direct and get their advice. Afterall, we're all just guessing. Go to the horses mouth. They will be more than happy to answer any question you have.

BME 50 won't run.
 

Just checked the pulse and it coming out of the crank case ok. I have the flat side of the flappers against the carb body. I am again clueless.

BME 50 won't run.
 

bdphil,
Did you ever get your 50 running?

By the way. If the neddle inside the carb on the diaphram is not set properly your engine won't run either. Try going to a good lawn mower repair shop to get this checked out. It's a good source of carburator info and since you've taken it apart already you might as well get a professional to take a look at it. I've had good luck with lawn mower repair shops in my area and they were always willing to help.

BME 50 won't run.
 

I just read the post on the crossed lines. Where does the pulse line go? On the back plate or the carb body?

No it's not running yet but I'll let you know as soon as I get it working.

BME 50 won't run.
 

Is the pulse line connected to the right fitting on the carb?

BME 50 won't run.
 

Just checked the crossed lines theory, no joy. I had it on there right. The fuel line goes to the carb body and the pulse line to the back plate where the diaphram is. As far as the needle settings I now have them a factory reset position which is 1-1/4 on the low and 1-1/2 on the high. On my first runs it ran great at these needle settings so again it is not the needle settings.

BME 50 won't run.
 

Bummer,
Why not call BME? They are really very helpful.

BME 50 won't run.
 

believe me I will call them. But it's Saturday and there business hrs. are during week days. So I am going to the flying field to see If there is expert on hand to fix it. But I'll wager $20 bucks no one can fix it.

BME 50 won't run.
 

Don't take this the wrong way but, did you take the carb apart or adjust the needles after the first few runs when it ran great and than you started having problems?