mranga

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Hello,

Iam new to gas engines. I think Ibought a dud engine. It starts and runs for about two seconds and stops. Any clues about what the problem could be? Could this be caused by an air leak (for example a bearing seal leak)?

Thanks in advance for your help.

Ranga

All Day Dan

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About the easiest thing to do, after you check your fuel lines and tank, is to rebuild the carburetor. What engine is it and can you see some numbers stamped on the carb? Dan.

mranga

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It is a turnigy 30 cc gas engine. I've tried  different carbs so I am fairly confident the carb is good.

I've been reading that these engines have bad sealing issues with the front bearings. Before I take it apart and replace the bearing with sealed bearings I just want to verify that such problems can result from a bearing seal leak.

Thanks for your reply.

Ranga

Rudeboy

It is not a bearing issue....sealing issues show up as idle-midrange tuning problems. Even with a leaky bearing the engine will run at anything above idle.

If it really just runs and stops after 2 seconds, and you're sure it's not the carb, then you must look elsewhere.

However, my guess is your engine is running on the "choking charge". Ignitions and bad bearing don't quit after 2 seconds every time.

ahicks

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I agree it's likely running on the prime. The carb has been changed, so wondering if you have checked/followed the pulse port to verify it's open, able to supply pulses to the carb's diaphram?

flyinwalenda

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As stated the engine is simply running off of the prime of the carb. The carb is not drawing fuel from the tank.
If the carb has a choke plate you can test by partially choking the carb after priming and see if it will run longer.
Are you using a starter or hand -flipping?
Use a starter,crank it up and watch the inlet line to the carb and see if it draws fuel.
Try opening the low speed needle of the carb a few turns.
If it's the chicom version of the Walbro carb you may have to open it up and adjust the float level and/or replace the diaphragms(metering, pump)  with Walbro parts.

mranga

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I am trying to start it by hand. I don't have a starter at my disposal. ( I would buy a used large starter if I can find one but I would be happy if I can avoid the expense of buying a new one. )  I cleaned up the silicone which was blocking the carb pressure pulse passageways. I am not very confident about the seals between heat sink and engine / heat sink and carb. However when I choke and block the carb opening with my thumb it draws fuel. Also choking draws fuel. I plan to cut some gaskets from better gasket material and replace them.

OldScaleGuy

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How about some of the simple things. Have you changed the spark plug and tried fresh fuel?

mranga

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I did change the spark plug to a NKG CM6 spark plug and I am using fresh 93 octane gas with 1:32 two stroke lubricant.

OldScaleGuy

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How about a clogged filter or clunk?

irocbsa

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What's you low speed needle setting? Almost sounds like the low speed is way too lean.

All Day Dan

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Ranga, don't start bending things in the carb. Here's the service manual for the Walbro WT. Remove the cover with the four screws on it. You'll see the metering needle lever. Push down on it and the spring should return to the lever back to its original position. The lever should be level with its immediate surrounding area. Was the carb new when you put it on? If not, rebuild it. Don't tighten those screws too much or else you'll crush the gasket and distort the cover. Then you'll have another set of problems.

http://wem.walbro.com/distributors/s...s/WTseries.pdf

Try the next easiest thing to change and that's the ignition module. Make sure that the battery has capacity and not just the right voltage. Dan.

flyinwalenda

My Feedback: (5)

The engine would have to have very low compression for it not to draw fuel . Usually when they have leaks they just run poorly .
You are positive you cleaned the hole out for the pulse port on the engine, carb spacer, and carb?
Positive the gasket isn't blocking/covering the hole?
As I and others have stated , open the low speed needle a turn.
It looks like the carb has a choke plate. Did you try to start it with the choke on halfway ?
Try injecting some fuel into the engine (using a squeeze bulb/can ) via the carb throat and get it wet. Or prime prime prime until you hear the engine get wet(you will hear a squishing sound) and then start it.
To adjust the float you have to take the plate off of the carb, remove the diaphragm and adjust the forked lever/tang but it sounds like you aren't too familiar with that so I would say don't do it.

Do you have a starter you can borrow? Sometimes some of these engines need an electric starter to get them running for the first several times.

apalsson

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These symptoms indicate a problem pumping fuel into the engine unless assisted by the choke. As long as you can confirm the fuel tank and lines are properly set up, I'd look at the following

I wouldn't be chasing after leaking front seals etc. Your engine should run even if you has some leaks unless they were severe leaks.
I would have a look at the reeds to make sure they are seated properly. Many of those cheap engines have a poorly cast reed cage where the flashing hasn't been cleaned off the edges, preventing the reeds from sealing properly.
Second thing and after you have confirmed the reeds, pull the pump cover off the carburettor and make sure there is no dirt or debris in the screen.
Now, fill up the carburettor pump with some clean fuel and close the carburettor.
Set the needles for roughly 2 turns each and see what the engine does. It should fire for you.
If you can run with the choke half closed, you have a fuel draw issue

jp1961

I'm not so sure it ISN'T a seal problem. I bought a very used Sears (Tanaka) Gamefisher 3.0hp outboard. Being a fairly competent mechanic, I tried EVERYTHING to get it to start. All I could get were a couple seconds of it running on starter fluid. After disassembly, the top seal (crankshaft seal) of the engine was completely out of the crankcase. Another thing I would investigate is, is the fuel tank vented. I'd say it is as it should run for longer than a few seconds. I've added another item to the,,, if it's got compression, spark, gas AND THERE ARE NO VACUUM LEAKS, it should start.

Jeff

huck1199

Could it be that the ignition won't work at normal rpm ranges?

[email protected]

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your first proplem is it is a .turnigy engine buy a good name brand

irocbsa

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That doesn't help at all. Start another thread about how great other engines are. This one is intended to help with a fuel draw issue that I'm sure we'll get figured out without your "assistance".

[email protected]

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sorry about thay i guess you know everything

mike31

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Two strokes need good rings to draw fuel. Just saying

mranga

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Thank you all. Your willingness to help has been terrific!

mranga

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It has an electronic ignition so I don't think that could be an issue. It is an air leak somewhere It think. If not the carb then the bearing seal (less likely from what I am reading) or maybe both.

I will start with the carb seals first, tinker with the carb adjustments as indicated and take it from there.

apalsson

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They won't help much if the reeds don't seat
Most of these cheap engines have extremely poorly cast reed cages
I have done up more of them than I care to remember

Lightning Fan

My Feedback: (17)

This thread:
http://www.rcuniverse.com/forum/m_96...tm.htm#9695879
has at least one guy replacing the ignition module to get this brand engine to work.

I had immense problems with a used G62.  I was not familiar with the engine, and like others have said, the final answer was that the pulse port was partially blocked by the former owner's poor attempt at a gasket.
However ... the engine ran longer than 2 seconds, even when the port was partially blocked it just would lean out at high throttle and die.

You said that she would start after priming and then not fire again regardless of what you did.  I wonder if your ignition module is capable of a few sparks and then shuts down.  If you could borrow an ignition module, it is easy to set up for an experiment. Perhaps also, go through the sequence until she will not start, then check the spark by turning the engine over by hand and listen for the click.  If no click, pull the ignition lead off, make sure the module ground is still good (I do not know if your module uses a shield ground or separate braid), put a short length of 1/4" OD metal rod in the plug connector and check for spark on the engine case.
Perhaps others have better ignition module troubleshooting ideas as well.

Good luck ... I had the worn out arm syndrome for a few days too.  You'll get it.

closetguy

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you have tried everything else,now try replacing the ignition.i have had many problems with the rcexl nockoffs ignitions.