pattratt

My Feedback: (1)

Hey Guys
I am running into major problems trying to keep the fuel pump on the 170 DZ working! I have two new engines experiencing the same issues. after 20 flights or so the fuel pump will just quit working. the other engine got around 40 flights before it started giving me problems and it too just quit pumping. I sent it to Richard V, after a phone conversation. Evidently there is a main pump housing plunger that is is not user changeable as there is no part number or parts break down on the plunger. I have all the other pump/regulator parts and have changed them several times. This includes all the gaskets, "o" rings, springs, valve, and diaphram. I have checked and changed every gasket and "o"ring on the entire engine. I have also tightened every nut bolt and screw on the entire engine. I am using 30% LS Cool Power double filtered and turning a APC 19.5x11.5 prop. Engine has great power and runs cool when I can maintain fuel pressure. It's been at or near 100 degrees the last month or so and I fly at sea level. I check cyl. head temps after flights and they are cosistantly in the 140 degree range so I do not think it is a temperature issue! I have not received the first engine I sent to Riachard several weeks ago and now it appears I am going to have to send this one to him unless I can get some feedback or ideas from you guys!! I am very experienced with YS engines and have never had one that I could not diagnose problems when they occured? I am so frustrated with these engines I am considering going to electric!! Thanks to all for any suggestions.

Regards
Dick

cdodom

Dick,

Does the pump have trouble getting the fuel as you are starting up the motor? Also, does the motor run fine after it gets the fuel?

pattratt

My Feedback: (1)

Hey Chris
I can get it started by capping the vent , pressureizing the tank, go to full throttle. then spin over with starter. I then release pressure turn ignition on and start engine. It will run out the prime and die! When the pump is working correctly all I have to do is go to full throttlr, no ignition, spin over with starter, turn ignition on, go to high idle and engine will start and run fine.
Dick

cdodom

I do not run the CDI anymore but what I do for my regular glow setup is I have a "T" fitting in the fuel line, so when I fuel up it puts fuel in my tank and primes the pump at the same time. so far this setup has been bulletproof for me all this summer.

How long do you wait between flights?

pattratt

My Feedback: (1)

Chris
The problem has nothing to do with 'priming" the engine. It has to do with the pump providing "fuel pressure" or the "lack there of" after the engine starts! I also use a "T" in the tank to engine supply line for fueling.
Dick

amram

Hello Dick,
I am also very experienced with YS and I am experiencing the very same problem with 2 motors.
All details of the problems as you describes are very same so I have nothing to add.
Also, it got nothing to do with priming or starting sequesnce. I am trying to resolve it directly with YS.

At some point YS have requested me to remove the pump + regulator and send it to them. I did so and still waiting report.
In the meantime, I took a regulator + pump from and good solid working YS170DZ and install it on the 170CDI.
This helped for about 20 flights. Now same problem came again. As said this is happening on 2 motors.

I am trying directly to resolve this with YS. Lets keep in touch on this issue.


Amram Leshed
F3A Israel

pattratt

My Feedback: (1)

Hi Amram

Yes, lets keep in touch.
I have heard from several others that YS may be aware of a prblem.

I will be talking to our US distributor tomorrow.

If anyone else is having any pump issues please chime in on this thread.

I will post any constructive info I may get.

Thanks
Dick

Hey Brett
Please give me a call on my cell when you can'
Thanks

amram

YS is very much aware of this problem.
I cannot see how your local distributor will be able to help beside giving you a new motors which also guarantee nothnig.
Let wait and see.
Amram

Wasson

See http://www.rcuniverse.com/forum/m_90...tm.htm#9001464

A very common issue with YS170's - both glow and Cdi.

YS 160's did not seem to suffer from the same problem.

apereira

Myself personally nor any of they guys that fly with me experienced this before, and as I recall discussing this with Amram, I was convinced you guys have a vapor on the pump due to hight temp, this temp, does not have anything to do directly with the engine working temp, but after you land, that's when the bubbles are generated.

When something similar happens to me in hot days, I flip the prop by the spinner just at the point where the pump actuates, that's BTDC and back, you can see the fuel moving through the line so you are sure the pump primes, the starter will not move the fuel the way this method does, not even half, try it.

Based on my knowledge on the YS engines this is all I can figure out right know to contribute to your problem, as it's not like having the engine on hand, but I think what you guys have in common are high temps at your field(100F).

Good luck and let us know

P.D. Amram, glad to read your Axiome is flying great!!

rcpattern

My Feedback: (45)

Dick,

Mine did the same thing this summer when it was really hot. Even though it didn't run hot, it would take 15 -20 minutes to cool at least before I could fly again. Solution was a 5.00 battery operated fan that I just set in front of the motor after landing and it kept airflow moving over the head. Within 1-2 minutes it was cool to touch and would start easily then.

Arch

klhoard

My Feedback: (10)

Yeah, I heard alot of guys are installing "battery operated fans" nowadays. . .
.
.

jim woodward

Sorry to hear of your trouble. Once this trend develops, does it happen "every" flight, even when cold for the first flight on a fresh day? Or, does it only happen if you try to fly within 15-20 minutes or so of flight #1?

Also, you may want to consider regular 30% heli in the summer heat. Or, take regular Cool Power 15% (the green stuff), and mix it with the 30% LS Heli for dead of summer flying. Please let us know how it goes for you.
Thanks,
Jim

Wasson

I agree with Amram. He is an experienced YS user and I don't think his problem has anything to do with his priming or starting sequence.

I think one of the main causes may be premature wear of the poppet valve seats. As I stated in my earlier post, this was not a problem with YS160's. However the pump assembly in a YS170 would appear to be different in several fundamantal respects, including the length and stiffness of the poppet valve springs and the detailed design of the seating arrangement. I am not exactly certain what the logic was for changing the design. No doubt Yamada will have had their reasons. It may have been the need for slightly more volume (YS170 glow versus YS160 glow) coupled with the need for a slightly higher pump delivery pressure. Whatever the reason, YS170 pumps seem to fail much more quickly than YS160 pumps. Around 80 to 100 flights is not uncommon for many reported failures, though I have also know some to fail at the lower mileages mentioned in this thread.

I don't think that ambient temperature is the main cause either.

It would be worth re-reading Arnstein's thread - http://www.rcuniverse.com/forum/m_90...tm.htm#9001464

Baking hot summers are not something that we normally suffer from in Norway, or in Great Britain for that matter!

rcpattern

My Feedback: (45)

After several thousand flights in very similar conditions that Dick flies in, I would be inclined to believe it is vapor lock. I used to live down near where he is, and even on the east coast I've had the issues. Ambient temperature isn't the issue, its how hot the motor gets after a flight. Motors get much hotter in the immediate time frame after a landing, especially with the CDI units. Adrian Wong and I have talked about this. My exact issues went away immediately after I put a fan in front of the motor to help get it cooler faster. It happened on new motors as well as motors with many flights. It was also MUCH more prevalent after switching to the CDI.

Arch

cdodom

I agree with arch on this situation. when practicing before the NATS I would get done flying and set a battery powered fan in front of the cowling of the airplane to help push some of the hot air from the cowling. Before I started using the fan it would take at least 30 minutes for the engine to cool and even then the motor had trouble getting the fuel. Using the fan it cut my waiting time down to about a 15 minute wait and would start up every time. Also remember I am running Glow instead of CDI.

hope this helps.

pattratt

My Feedback: (1)

Hi Arch

The problem is not in getting the engine to start. As I stated earlier, I can pressure prime and get engine to run. The problem is it will not stay running even at a high throttle setting. When the pump quits working after 20 to 40 flights the engine can set all night and problem persits the next day. It is not a temperature problem unless it is a result of a high temp while running the previous 20 to 40 flights that is "WEARING" something. The pump is being cooled by RAW fuel from the tank and I do not see how that could be a problem. The second engine was broke in with a progression of 18.1x10 to a 19.5x11.5 over a 10 run cycle, running "RICH!" As stated by others , when the engine is cool and pump is working you can see the fuel moving in the supply line by rotating the prop around the "intake push rod movement of thw cam cycle. Once the pump completely fails this does not occur. Prior to complete pump failure the engine will require constant "richining" to keep the top end rich which has the negative effect of screwing up the idle and mid-range. My problem is not related to the pump plastic check valves but rather something going on inside the pump body where the pump plunger is located. I know because I have changed all the internal parts that include the check valves , springs, diaphram, and gaskets.

Thanks for the reply.

Dick

Hey Arch
Just saw your second post. I have experienced many times the condition of vapor lock in the process of getting to the 40 flights. This can occur if you attempt to fly too soon after a previous flight and can also occur if you run the engine too long on the ground. Then you must cool the engine with a fan, time, or by pressure priming the engine until enough fuel has been injected to cool the pump. What I am describing has similar symptons but with pump failure, occurs on a cold engine.

pattratt

My Feedback: (1)

Just thinking out loud.

When the pump is working correctly this is the best engine of all time. This pump-regulator system is very precise when working properly! I wonder what the "dynamic" was in YS going to this system rather than the pressure tank system that did have some mtc. issues but was very easy to diagnose and repair.

The only advantage I see is a very precise and consistant idle & mid range. I am sure there is a lot more to it than just that!

Dick

apereira

One thing is for sure, it's very difficult to have this kind of identical problems in two different engines, so, it will be advisable to study what's the common factor causing this, as well as wait for Richard report on what's going on with the engine.

The pump on the 170 was improved for hot day operation that the 160 suffered, but it might not be enough, another thing, priming the pump before every flight dos not assure the air bubble will come out if the same condition persist, a small air pocket forms on top of the pump, I've cleared this after three flights (average).

If you keep richening the pump, then is an indication of pump failure as you describe for sure.

UKpatternflyer

Hi Dick,

So are you saying with the pump valve asembly untouched, you can fix the problem by changing something in the pump piston (plunger) area of the assembly? Or are you talking about the pump regulator where the pressure relief diaphragm (diaphram, spring and brass screw)

And in doing this you can reinvoke the problem by changing back to the original parts?

Regards

Keith

pattratt

My Feedback: (1)

Keith

After talking to our US dist. Richard V. I learned there was a "plunger assembly" inside the main pump housing that appears to not be a user replacement item as there is no parts break down or part number for this item. Richard was going to send me a new pump but have no way to test run the engine other that putting it in the aircraft so I sent him the engine to replace the pump and test run on his "Test Bench!" I have all the other parts and have changed them with no sucess.

Dick

MTK

Arch,

Can you move the pump from its current location to a point further away from the cylinder? Maybe a set of stand offs to move it forward some (1/2"). Possibly even a plastic base to mount the pump. It sounds like more insulation from the hot cylinder may be required, particularly after a flight when the engine just sits and bakes. The fan idea is a good one

It is very telling that the CDI version is seeing more of an issue with this. The glow version requires a richer (cooler) set-up and uses a higher oil content fuel.

Will the CDI engine run okay with standard, high oil fuel, set rich? The milage will drop but hell, if it will save the pump, and all the aggravation, it may be worth it

pattratt

My Feedback: (1)

Mattk

The pump is intergal to engine as it uses intake valve train to operate the pump.

Dick

MTK

Dick

Thanks....is there any room to add insulation behind the pump? McMaster Carr carries ceramic insulation paste that is water based but dries hard. Don't know if it would be compatible with glow fuel but even 1/8" thickness buys something. Just a thought

pattratt

My Feedback: (1)

Mattk

No, that would block critical airflow over the engine cyl.

Dick