hoverlow44

I have a 3W 75i. I initially had issues getting it to draw fuel. Even with the choke on, it wouldn't draw. So then i covered the Carb with my thumb and started turning the prop back and forth on the compression and it finally got wet. Once it was wet, i flipped the ignition on, and at the third flip the engine popped into life and shut off because choke was on. then I removed choke and again at the third flip it fired right up. it was running alright, except that idle had to be quite high for the engine to stay on. I leaned out the low end about 1/8 of a turn and fired her up again and life was good. I take a 10 min, drink some water, chill out, and i try again, and same deal, carb gets wet, with ignition on and choke on engine pops, i open the choke, and flip her 3 times, and at the third flip this time, she starts up for about 1.5 seconds and then dies. I repeated this process like 7 more times with no luck. Ignition batt. is good. Fuel is good. Sparkplug is new. i checked the diaphragm in the carb and it looks good, no cracks, still flexible. So any of you 3w guys out there.. what do you think?

hoverlow44

I also have the needles at stock setting. H: 3/4 turn L: 1 turn. Well, started at those settings anyway.

All Day Dan

My Feedback: (5)

Replace both diaphragms, screen and gaskets in the carburetor. Check the metering needle for movement and for any wear on its tip. Also make sure its seat is good. Dan.

hoverlow44

All day dan, What should i look for to determine it has a faulty diaphragm?

speedracerntrixie

My Feedback: (29)

the 3W engines use a Tillotson carb and they are a bit more sensitive to adjust then the common Walbro. 1/8 turn is a pretty big adjustment. try setting the needles to L 1 turn and H 1.5 turn. These will be rich but very runable settings. Lean in small increments.

hoverlow44

Speedrace, i will try that. Once i leaned out the low end i noticed that the engine became harder to start. The reason i leaned it out was because idle had to be a bit high for the engine to not die. Then again i might be wanting a really low idle. Do you believe the diaphragm could be bad?

All Day Dan

My Feedback: (5)

Unfortunately you can’t tell when a diaphragm goes bad by looking at it. I change mine as soon as the engine gets cranky. It usually helps. If you live in an area where ethanol is added to the gas, the diaphragms do not last long. Keep in mind, that the gaskets should not be reused once they are removed. Dan.

speedracerntrixie

My Feedback: (29)

I agree, my policy is that if the carb has been dry for even just a few weeks I don't even bother trying to run the engine until I get a rebuild kit in it. I will usually leave a few oz of fuel in the tank to keep the carb wet between outings to the field. Best case scenario is that you get it running ok but as the flexible parts in the carb get exposed to fuel they will get even more pliable so the next trip out you needle settings will have to be adjusted again. The best way I have found to deal with this is always keep fuel in the carb and throw in a kit every year along with rebuilding the tank.

hoverlow44

i talked to the guy at aircraft international, and he says that it sounds like the sparkplug cap is corroded and not making good connection. He says he doubts it has to do with the carburetor. Im at a loss haha. Ill just start buying parts and replacing them until it runs i guess.

speedracerntrixie

My Feedback: (29)

I'm not going to say that it is not ignition related but I can say with 99% certainty that if the carb has sat dry for any real length of time it will have issues. If you have suspicions that it may have other issues, then the best thing to do is send it to AI and have them do a complete diagnostic. Setting the needles to what I suggested and trying it again may verify the ignition is good or bad. If you can get it running and transitioning to full throttle without an ignition miss then it would still be the carb.

hoverlow44

i will try again, and if i cant do it, ill just send the engine to AI and have them figure it out and install the needed parts. Might be more efficient than me trying to guess and order parts every time.