Any help in troubleshooting the pump on my 140 Dingo would be appreciated. Even when activated by hand using the pushrods it will not pump. It has ben disassembled and checked for foreign material and flushed out with fuel.
The plunger seems to be O.K. but I can't tell for sure. Is there anything else I can do?

Thanks.

Dave G.

There's a whole lot more to that pump than just the plunger/diaphragm when you remove the cover. Plus, operating the pump by hand probably won't cause it to pump, because in addition to the mechanical motion of the pushrods, it also uses crankcase pressure. I would recommend a complete disassembly of the pump (using a proper assembly diagram as a guide), clean everything out, and re-assemble properly. Worse comes to worse, send it to YS parts and service and they can get it working again. A buddy of mine was having trouble with the pump on his brand-new 170. We were trying everything to get the engine working since it had run fine earlier in the day. Eventually what I did was, with the pump cover removed, I blew air into the vent side of the tank, forcing fuel to spit out the pump. Once we re-assembled it, the pump worked fine. We call that the FM method ($^%&ing miracle method) of fixing things.

Hi Dave,

Operating the pump manually will show if it is working providing the little valves and springs are doing their job.
The pressure side of things has nothing to do with testing the pump, to explain,
The front vent line from the pump to the crankcase runs at a pressure above 2000 rpm and at a vacume under 2000 rpm or there abouts.
Under 2000 rpm the pump does not work and fuel is sucked in as per a normal engine, above 2000 rpm there is pressure and the pump works, this is all controlled by the regulator screw / diaphram, if the regulator was adjusted correctly there will be a pressure on the diaphram when the pump is off the engine, it requires a vacume on the diaphram for the pump not to work.

Back to your problem, the little plastic valves normally do not give any trouble, but if they have not been put back correctly the pump will not work, this is easy to check,
get a syringe and a piece of fuel tubing put the tubing on the syringe and the other end on to one of the pump lines, in or out, now if every thing is correct you will be able to move the syringe plunger in easily or out easily, but only one way the other way will have resistance, now test the other line, it should be opposite to what you just had.
If this is so the pump should work, if not the pump will never work until you get the valves right.
You could also have a hole in the diaphram.
If every thing is ok and pump is still not working, use the syringe to purge some fuel through the pump, it should now work manually, I assume that you have fuel tube attached and the ends of the tubing is in a can of fuel, now work the pump and watch for air bubbles, if there are bubbles you need a new pump, no if's no buts.

A trap to be wary of is that the 160 pump and the 170 pump are two differant pumps, you cannot mix and match parts, the only parts that can be used in either pump are the valves and the diaphram, you can't swap pump bodies over.

I have found that a few of the 170 pumps are giving problems in the valve area, they work and then they don't work, and then they work again and so on. This has been due to poor machining, and new parts are in order.

Will Crossman, Aus

Thanks for clearing that up, xmans.

Glad to help out

Thank you, WC for a great explanation on the workings of the pump. I will give it a go today. Hopefully I will not have to resort to the "FM Method" that MJF used to solve his pump problem.

Dave G.

O.K., I got the pump working , but only after I found that the small poppet valves had been installed backwards. It now pumps like a 3 alarm fire engine. However, all is still not well with the engine. With a 16x12 APC, it only turns up to 7000 rpm. I can get the idle down to a unsteady 2,000.
Other pertinent facts:
Engine has a new piston & liner
Excellent compression.
Pump adjustment screw flush with housing.
Valve timing checked as per manual and also using a degree wheel.
Valve clearances O.K.

I used 15% Cool power for fuel. I am aware that a higher nitro fuel is recommended but I can't believe that it would make a 1000 rpm difference.
I feel that I have overlooked something but can't put my finger on it. Perhaps XMans can offer any suggestions?

Thanks.
Dave G.

Those little valves can be annoying. I know for a while there was a diagram floating around that was drawn incorrectly showing reverse installation of the valves.

I have never had a good experience running a YS 110 no less a 140 DZ on anything less than 20% nitro. Also I believe the 15% is 16% lubricant. I believe 20% should be the minimum.

I always add a couple of oz. of sythetic to every jug of fuel so lubrication is not a problem. I did run the engine on 30% heli the other day and I still am down on power - 7300 on a 16x12 APC. This engine is becoming a pain.

DWG

Hi Guys,

I don't get on all the time but I do try to see what's happening.

So it's still not running right, ok, first off I never run less than 25% nitro and min of 20% oil.

So when it is running at higer rpm's does it sound angry as if it's on the lean side, and has it back fired and or thown a prop??

I believe you have a air leak or the reg is not adjusted properly.

An air leak is simple to diagnose if you have access to a Vacume/pressure gauge,(used by motor mechanics), insert a tee piece in the front vent line, thats the one from
the crankcase to the reg/pump assy and attach your gauge to it.

Run the engine and there will be pressure, now go to idle and there should be a vacume, depending on the overall condition of the engine, the newer the engine the higher the vacume.
If there is no vacume at all you have an air leak some where.
If all is good then I say the reg is not adjusted properly

WC YS Service Aust

Here's my $.02 worth:

The 20% Nitro will make the most difference at idle speeds. Your idle will be much more solid and reliable with 20% than it will be with less nitro content, even if it's only 5% less. Don't expect higher nitro content to cause a huge increase in RPM's at high speed, it won't happen. At least it doesn't with my YS engines.

Does it run smoothly at 7300 RPMs, or is it running rough? Does it smoke well, or do you have very little smoke output? Does the engine act like it's running hot? Does it have smoke coming off it after you shut it down?

I'll bet it's running lean at full throttle. Try richening the regulator and/or the HS needle some until the engine seems to be running rich, with lots of smoke and running sorta rough, and then lean it up to the maximun RPMs. That's the best way to get the maximun out of whatever fuel/prop combination you're running.

Also, you might try a little less pitch on that prop. A 16x12 might be bogging the engine some. I like a 16x8 on a 140 size engine.

David

The 16x12 prop shouldn't be the problem. I run 17x10 or 17x12 on mine.