grbaker

My Feedback: (29)

When I rotate the prop hub slowly, when the magnet passes under the pickup I do not get a spark at the spark plug. If I rotate the prop hub quickly, it will spark. Should I be getting a spark regardless of rotation speed?

The reason I ask, is that I am having a difficult time getting this motor to start and run consistently. I have replaced the ignition (with another one from 3W), the magnet and the carburetor. I also tried a new pickup, but it does not work as well as the old one does. Now I'm wondering if I might have a timing issue, but it is difficult to see where the timing is set, if I have to rotate the prop hub quickly past the pickup.

This engine is a 15 year old 3W-60K (side intake) that has sat up for 12 or 13 years and now I am trying to use it again.

Any help would be greatly appreciated.

CK1

My Feedback: (60)

Gary , You should have spark regardless of cranking speed .
If you are trying to use a new style sensor with the old module they may not be compatible .
I will assume you are using a known good and fully charged battery.
If using the original module and sensor and there is no spark or weak spark the most common problem is the plug wire cap. (replace it )
If using a newer module be sure you are using the sensor that came with it .
If none of the above resolves the issue , send it to your preferred 3w dealer for diagnostics and repair.

Antique

My Feedback: (4)

Old style 3W ignitions do NOT spark at slow speed, the sensor is not a hall sensor, it's a transformer with only 2 leads...
New style sensors will not trigger an old style ignition...If the plug doesn't match it won't work....
If yu havent rebuilt the carb, do it...DG5HS-T is the carb kit number...

grbaker

My Feedback: (29)

The new ignition I have is sold as a replacement for the old style ignition. I tried my 13 year old ignition and it works exactly the same as the new.

I bought a new carb for it, but have not been able to get it to run with the old or the new carb.

I use the 3W starting instructions ..... propping it 10 to 12 times with full throttle and choke closed - ignition off. Then turn on ignition and flip the prop till it pops. (All good to this point) Then open the choke and flip and flip and flip and flip...and flip some more with an occasional pop. It almost sounds like a backfire thus leading me to check the timing.


The weird part is that I have started this engine several times over the last month with no issues and have flown the model 3 flights (on 3 separate days). On two occasions I have flown the model successfully and then fueled it for a second flight. Both days I was unable to start it for the second flight. The first time this happened is when I decided to replace the ignition module. The second time this happened was with the new ignition module installed. That’s when I ordered the new sensor and magnet. I replaced the magnet and the sensor but the new sensor doesn’t seem to work as well as the old one.
Going to go get some new spark plugs today and try to get the timing as close as I can to 27 degrees. Maybe I’ll get lucky.

CK1

My Feedback: (60)

I purchased my 3W60k the first year they were avail. (not sure of the year , mid to late 90's ? )
It has 3 wire crank sensor and will fire any time the magnet passes the sensor (fast or slow ) .
Antique - Is this the old -old or a newer old system ??

Antique

My Feedback: (4)

Thge really old old won't fire with slow rotation...There are 3 wires but one goes nowhere...The sensor is a small steel pin about 1/16 diameter with lots of fine wire wrapped around it inside the black housing...It takes fast rotation for the ignition to fire...If the top comes off the housing you can see the wire.......NO hall sensor in there...

grbaker

My Feedback: (29)

I purchased this one in 1995 or 1996. First flew this model in '96.

grbaker

My Feedback: (29)

Well I was all wrong about the timing in my earlier post. I might have had my thinking cap on backwards.

I was able to check the timing with my old Sun inductive timing light. The range by moving the sensor from stop to stop was from 5 degrees before TDC to 5 degrees after TDC. Looks like someone at the factory forgot to I drilled new mounting holes and can now set it at 27 degrees. I'll try tomorrow to start it.

Thanks for all the help!!! Wish I had posted before I bought the ignition. The only reason I bought the new one was due to the lack of spark when rotating the crank slowly!

grbaker

My Feedback: (29)

Well, I got it started and it ran real good............backwards. I guess I'm going to have to box it up and send it to someone that knows what they are doing.

rc bugman

My Feedback: (30)

If I were you, I would send it to Ralph (antique). He gets all of my engine work and does excellent work. My only gripe is that he does not charge enough for the quality of work he provides.

Elson

Steve S. Helland

My Feedback: (15)

Make sure you replace the front and rear seals while you are at it. I have had a few bench queens in my time and noticed that when I let them sit on the shelf for a few years they don't run right, have poor running characteristics such as in flight leaning, RUNS great on the ground but up in the air bad, etc.

grbaker

My Feedback: (29)

Well, there may be hope for me after all. After a full night of sleep I went back out and pulled the engine from the airframe and built a little engine stand for it. I hooked my timing light and installed the degree wheel to recheck the timing. With the timing set at 27 degree BTDC, the engine will only start in reverse rotation (clockwise) every time.

I was starting to have some issues starting it, so I pulled the plug out to check the spark and noticed that the plug would fire 2 out of 3 rotations, but the timing light fired every time. Guess I need a spark plug cap. So I installed the old ignition and moved the pickup sensor back to the stock location. Now it starts easy every time with the timing set at about 10 degree BTDC. If I kill it and let is sit for 10 minutes or so, it starts on the first flip every time. If I wait 30 minutes it takes 2 flips.

I'll test it a few more times tomorrow and if it still runs as well as it does now, I will re-install it in the P-39. I ordered a couple of plug caps, so I will replace the one on the new ignition and use it as a backup.

Thanks for everyones help. If I start having problems again and need send it out, I will surely contact Ralph!