3W 75 Problem solving......

[steven_gene]

Hey Guys

I have a 3W 75 in a wild hare giles 202 and ever since I got the model all the motor has done is give me trouble!!!
So I need your guys advice on what could be wrong.
From the get go the engine hasn't been the best runner (very poppy and slow pick up no matter how much tuning me or anyone does) but ive made do! But the engine has progressively got worse.
Now when I try start it it take along time to fire and when it does start, it runs for a second or two and then it stops. Im guessing its something to do with fuel geting to the motor but whats causing it??

So ive eliminated the following....
-Ive tried a different fuel tank
-Different Clunk
-New fuel
-New fuel filtter
-New plug
-New carb kit (diaphagmes etc)
-There is a decent spark
-Batteries are fully charged

This motor is really starting to get on my nerves, and i dont have the money to go buy a new one!!! so any advice to try get this motor running would be muchly appreciated.

Cheers
Steve

[sweetpea]

Have you tried a different ignition?

-an ignition going bad can cause these problems or if it just has a weak spark.

Also have you tried a different type of battery?

-I had a battery (5cell NIMH) that would run the engine fine for about 3mins. Then I'd drop a cylinder and get it back if I went back to idle. Fought the motor for a good month until I swapped the battery out for a LION. The NIMH always charged fine and showed good voltage.

[Vic3D]

Have you worked the needles?

[Blip]

I guess you cleaned out all the carb jets before you fitted the new diaphragm and seals?

I bet sweetpea nailed it with the suggestion of ignition or battery .....either that or the sensor plate has moved on its fixing screws throwing your timing off.

[steven_gene]

Blip
Yea I took the carb to a lawnmower place to get the diaphagms put in and they gave it a once over at the same time! But i might check them and give them another clean!!
I was wondering about the timing but i dont have a clue where to start with that lol.......Ill have a look for some instuctions and check it out.

Vic3D
Me and a few other people have tried tuning it but none of us can get it right. It would seem to be running mint but as soon as you start flying it just boged down and wouldnt peform...and now we cant even get in to start and stay running.

Sweetpea
Hmmmmmm Batteries thats a good point. I dont know how good the battery is, it looks like a cheap one. But Id like to leave this resort till last coz im a bit short on chash seeing as im still paying my parrents back for the plane!!! But for future what sort of size/type battery should I look at and do you know where I can get a cheap one?

I thought it was more of a fuel thing because if i squirt some fuel down its throat it starts but only for a second or two. But I dont know what else to look at to try totally eliminate that thought.

Cheers
Steve

[3ddd]

u changed all the fuel lines and clunk and all but did you zip tye them so no air is getting in the fuel lines and are you sure the choke is opening and closing completely

[rcflyer007]

IF YOU HAVE TRIED ALL THE ABOVE THEN MAYBE YOU MIGHT CHECK THE REED VALVE BLOCK AT THE BASE OF THE CARB. IF THEY DO NOT SET IT WILL NOT DRAW FUEL. JUST A THOUGHT.
ALEX

[WangoTango]

Steven,
Good thing you're asking questions on FG! You'll get a bazillion different things to check. Just a feeling but I don't think its a fuel delivery problem. You said something about "popping." If the adjustable hall effect bracket is too far clockwise or counter clockwise, you can get this problem. If it's too far one way it could knock your hand off kicking back. (Ask me how I know!) Maybe Ralph (RCIgn) can chime in on this one......... He fixes ignition problems in his sleep!
WT

[Blip]

Hey Steve
Don't worry about the sensor ring too much and its prolly best not to mess with it in case you create more problems for yourself until all other solutions have been eliminated. Just look at the 2 screws securing the plastic ring and see that they are approximately in the center of the slotted holes which will be pretty close to factory settings and of course the ring doesn't move when GENTLY rocked, no damaged wiring etc.

	Quote:
	Me and a few other people have tried tuning it but none of us can get it right. It would seem to be running mint but as soon as you start flying it just boged down and wouldnt peform...and now we cant even get in to start and stay running.

You say the engine runs fine on the deck but only changes when its flying correct?
Take it back to when that performance last happened. No doubt thats still the case once the needles are re set to factory standards, you've most likely played with it so much by now that every setting is off the map, so get it back to default and lets take it from there.

If your ignition is running fine on the ground for some time but not in the air.....it means theres a high probability its not the ignition at fault and must be the fuel system since the ignition module is solid state theres no moving parts....assuming of course you don't have loose connections that vibrate whilst in flight like spark plug cap and ignition leads, plugs. But you've already checked them I hope?
It would be worth while borrowing a bat pack if you cant afford one just yet from a fellow flyer to eliminate any battery doubts or you may find your chasing your tail by doing other adjustments that were never needed.

I'm wondering if it is a fuel problem caused by being starved.
What model type is the engine CS or US because side induction and rear induction can suffer different problems relating to similar causes with regards to fuel intake flow from prop wash and turbulence.

Is the engine new or old? In your first post you said it ran bad from day one in the model and again i wonder if its old, it may have been messed with by the previous owner. If it was new then it could be the setup in the model thats causing it. (as mentioned above) but if it is new it should really be returned to 3W and let them sort it or you may lose your 3 year warranty. Does the carb enter the fuselage and what ventilation in the engine box is there is if it does?

Re reading your comment to sweetpea you say the engine starts and runs when fuel is injected into the carb. Do you know if the engine sustains a longish run if you continue squirting the fuel in by hand? if it does then it sure sounds like you have a blocked slow speed jet. Don't go and try this if you haven't done so already its not very safe. I'm still convinced its a carb prob.

[steven_gene]

Thanks for all the advice guys!!!
I havent had a chance to try all of these things yet because ive been boged down with so much school work its not funny!!

3ddd
Yup all the lines have been tied on! And im working on it with the cowl off at the mo and the choke is definatly opening and closing completely.

Blip
I have the rear induction one. And all the information I have found about them seems to say that there not a very reliable motor. Wish I had found that out before I brought it!
I brought the model with the motor second hand so theres no warranty!!
Im on the prowl at the mo to borrow a battery!! There just arnt to many people that fly big planes round where I live so its turning out a bit harder than i thought!!
We've tried going back to the recomended start point on the needle (1 turn out on both needles) but no matter where they are it wont start.
At the moment im running it with the cowl off so there shouldnt be a problem with ventilation.
As you said I have a feeling this is pointing to a blocked jet. Ill try elliminate that problem next and go from there.

rcflyer007
I considered the reed valves the other day fundly enough when I was pulling a motor for my minibike apart lol whats the best way to check and fix these? Ill try the jet and if that doesnt succeed ill give these a go.

Thanks again for all the advice guys

Cheers
Steve

[steven_gene]

Lol jdearduff

Yea I wish I could just go out and replace it ae!!
I seem to be the only person in the IMAC group in NZ that flys 3W and I seem to be the only one who has problems!!!

[tonyc9075]

I have the 3W-60 that was acting up when I first got it. I bought it used. Turned out to be a reed problem. The reeds were split on the ends. You may want to look at yours next time your in the carb. Replaced the reeds and the motor is happy.

[steven_gene]

Hey
I just had the carb of to give the jet a quick clean and had a quick look at the reed valves at the same time. What should they look like?? Are they ment to be fully shut or have a bit of a gap?? mine had about a 1-2mm gap. Is this right or is this what could be causing my problems??

Cheers
Steve

[steven_gene]

Just had a really good look at the reed valves and it looks like they've been taken out before!! and now that ive taken them out and put them back in they have closed up and now theres no gap! maybe the previous owner didnt do the screws up tight enough, or they could of just started to come a bit loose.
Now all I need to do is put it all back together and hope that it runs.

Cheers
Steve

[brownj]

Steve,
FWIW, I have a brand new 3W75 CS (side carb) and the hall sensor is rotated in the slots almost completely CCW as viewed from the front of the engine. Not that this is correct for all engines, but that's the way mine is.
However, I also think it's a carb problem.
Good luck, hope you get it resolved.