26cc engine problem

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Fidelity101

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20
New engine with only about 1 gallon of fuel through it. Engine was running great and my Losi 5ive, stock, was going about 36mph. I ran the tank dry so I went out to the gas station to get some more fuel and that's when things went south.

Back at the field, full tank, pulling and pulling and pulling, I can't get this 26cc engine to fire up or even pop. So I figure it was the plug. Back to the store for a new plug, check the spark on the new plug and it's definitely giving a spark. Back in the engine, pull pull pull, not even a pop. Full choke, primer bulb is full of fuel, but it just won't start.

So back at the shop, I take the carburetor apart and clean it as much as I can. Put it back together after soaking it in gas for a while and now I can't even get the bulb to fill with fuel. The fuel tank is pressuring, meaning the carburetor is pushing air out of the exit and into the fuel tank which is pushing fuel into the carb. I pull the lower section of the carb off and fuel gushes everywhere so I know it's getting fuel. Put the bottom of the carb back on, pump pump pump the primer bulb and it's still full of air...no fuel. I'm stuck!

The carb is a WT-219 and it's the stock carb from the 26cc engine. I have ordered a WT-668 carb to see if that fixes my issue but I'm very confused on why this original carb just stopped working...or am I missing something? I've tried turning the needle valves all the way in and I've tried removing both of them completely, it doesn't make a difference and that bulb is not filling with fuel. Also, the intake area is full of fuel as the fuel seems to be coming up from the tank and since it won't go into the engine, it just pushes out towards the air filter. Very little fuel is making it's way into the engine.
 
The only thing I can think of is a small spec of dirt has made its way into the carb somewhere..... Prob find when you fit your new carb all will be well... here's hoping!
 
The fuel tank is pressuring, meaning the carburetor is pushing air out of the exit and into the fuel tank which is pushing fuel into the carb. I pull the lower section of the carb off and fuel gushes everywhere so I know it's getting fuel.

Check the vent in the tank. If it is clogged with debris. Everything you are seeing is what will happen. If it is the tank that has a disk in the cap for the vent system? Pull it out. Meaning the rounded bulb you see on the bottom of the cap. Pull it off. You will than see a small flat thin disk. Pull it out and put bulb back in cap. Reassemble and try again.
 
I think the only vent in the tank is the cap and you're right that there's a thin disk between the bulb and the plastic cap. I removed it, so the tank will be less likely to pressurize. I'm guessing the tank is not suppose to pressurize? Would this be the reason that my carburetor bulb is unable to fill with fuel and unable to push fuel into the engine? I did try priming the carb with the fuel cap removed but I never tried with the middle section of the cap removed...I'll give that a try.

The carburetor is a WT-219 carb and after a bit of research, it looks like it's discontinued. Horizon Hobby told me to try and replace it with this carburetor Zenoah zent207581000. However I already have a Walbro WT-668 carburetor that a friend is sending me so hopefully the 688 will be an acceptable replacement and I won't have to spent $70 on the Zenoah carb.
 

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Most of those carbs, most gaskets fits between them, minor difference is in the pump plunger, fuel valve, and aluminum dish (which almost nobody replaces it). A Ebay carb kit is around 3 dollars.

The orange portion of the pump can be removed with a skinny flat screwdriver, or a plastic clip similar to those used for opening the back of a smartphone. The prime bulb free of cracks, warped, reversing the line does not do anything besides clogging the carb and starving the engine of fuel on the top end. Possibly the white nylon plastic, prime bulb location, could be warped and not sealing correctly.
 
I'll have to take a picture of the carb when it's apart. The whole carb looks new and all the parts look new. No damage to the bulb, the orange piece inside the bulb, the diaphragm is intact and all ports look pristine. It's a WT-219 carb. The only thing I can think of is that there may be a small piece of debris inside the metal chambers somewhere that I can't see since I ran the tank dry.

Also, this is a picture of the plug I replaced...I'm thinking the engine is running to rich? Or is there something else wrong?
 

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Overly rich!

Fuel lines good, no cracks, Can you blow through them and bubbles come out into the tank?

Did you do the fuel cap mod?

There is a diy thread of a carb which walks you through each component.
Its so rare, clogged, air leak, but you say everything is new, and checked all parts.
The only time I had one, but the bulb would stay collapsed, was the fuel cap bad, and another occasion, minor silly cut in the fuel line.
 
Just looked at the pics you posted. With the fuel cap apart. The middle part has a doomed piece in it. That is the check valve you need to remove. It will let air in but any pressure in the tank will push it closed and seal the tank. No venting. Than pressure will build and no fuel can be drawn out of it. Also fuel will suirt out like a garden hose when you disconnect a fuel line.
 
Well the tank is getting pressurized when I pump the bulb several times. I'm replacing the fuel lines and cleaning the tank to be safe. By fuel cap mod, do you mean removing the center piece? If so, I'll definitely try that next time I start the engine up.

Ill have to find that video you're talking about and see where I'm going wrong with the carb. Seems to pump fuel into the lower portion of the carb but that fuel never makes its way to the bulb. If I keep pressurizing the tank, the fuel does find its way out of the carb and poors out the air intake side when I try starting the engine but the bulb never fills up and the piston never sees much fuel. I tried pulling the carb apart and soaking it in carb cleaner for 10 minutes...maybe I should try again and leave it soaking for a day to break up anything inside the carb that I may be missing.

Also, thanks for the tip on the plug. I'll lean the engine out when I do finally get it running. It was a stock engine and it's only seen about 1.5 gallons of fuel. 1 gallon from the previous owner before it sat for a while and then a half gallon by me when it was running great. I was getting 36mph top speed.
 
http://outdoorpowerinfo.com/repairs/walbro_wt340_carb.asp

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On the rubber dome, drill to make the hole at the tip a tad bigger

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Those three holes in the valve cap, same deal, twice as big of what they are...
Of course remove the one way valve before drilling, leave intact, let it do its job to seal and contain the pressure in the tank.


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Make the hole in the cap twice as big than original.
 
Thank you for the tips, holes are now drilled using a 1/16" drill bit. That seems to be about twice the default hole width. I drilled all the holes, cleaned away the shaved off material with some windex and reassembled the fuel cab....thanks!

In the mean time, I replaced the fuel lines because the car was sitting for a year or so before I bought it and I wanted to eliminate the chances of it having small cracks in the fuel line. A new fuel line assembly was only $19.00 on amazon. I removed the nipple in the fuel tank cap and reinstalled the cap.. I then installed a new WT-688 carb that just arrived in the mail today. It looks like it was pulled from a brand new factory engine because it's new but the included gaskets were indented. Anyway, it literally fired on the first pull! Lots of smoke coming out of the engine because I'm sure the stock needle settings are rich, but I'm back in business! I really think there is something blocking the old carb and I plan on soaking it in carb cleaner for a few days to see if I can salvage the carb, but at least I'm back up and running! It might not be worth saving because carbs are so cheap, but a backup carb in good working condition is always helpful to have.

A big thank you to everyone who provided some guidance on this issue!!!
 
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