greengrass

hi im thinking about using this with my os bgx how does this pump work eg. what lines go where and do you have to do something to the crank case for it to work

w8ye

My Feedback: (16)

Yes, you need to install a pressure tap into your BGX crankcase. You will run a piece of fuel tubing from this outlet to the little single outlet on the end of the pump.

On the outher end of the pump, there are two fuel line connections. The one on the right is the inlet that goes to the tank and the one on the left is the outlet tha goes to the carb. In between these two there is a pressure adjusting screw.

The pump works by the pressure pulses from your engine crankcase pushing a rubber diaphragm back and forth insde the pump. On one side of the diaphragm is the pressure pulses from your engine and the other side is exposed to your fuel. Through the use of two one-way valves, this fuel side of your pump draws fuel from your tank and pushes it towards your carb.

Flyboy Dave

My Feedback: (21)

Here it is....

FBD.

sport10

That pic is for a fourstroke setup. No need to vent the pressure line on a two stroke just run it to the pump. The only line that needs venting is the vent line on the tank.

w8ye

My Feedback: (16)

Well.... at least you know how to hook up each kind of engine now?

Jim

greengrass

guys i found this setup off the perrypump site is this the correct 2 stroke setup if not cand u edit this pic to show me how it should be setup

w8ye

My Feedback: (16)

This is the bypass set up for a two stroke.

Use this on some engines that do not have a pump carb on them and that do not run right when using the pump.

Then use this system.

JoeAirPort

My Feedback: (41)

That picture is with the bypass loop. You may not ned the bypass. The bypass is only needed if your midrange is too rich with the pump. Also that check valve will not work as an overflow very well so it needs to be left off. I'm not sure why he posts that stuff on his site when it's not really the way us airplane guys do it.

Here's the way to install it on a 2-stroke without the bypass. Works great.

JoeAirPort

My Feedback: (41)

If you really need the bypass I'd do it like this.

Rupurt

I just got one and put it on a fourstroke, works great( I didn't actually have a fuel delivery problem to begin with but as the engine was running with no muffler pressure I was a bit worried about leaning out on verticles). They don't market it as a fourstroke pump but I think they should.

greengrass

cheers for that man a even simpler set up i ordered it yesterday so in about a week it should be here (im in nz) so is there no need to have that check valve on for air?, and should i leave the muffler line connected to the tank?

Rupurt

No, no muffler pressure. put a loop in the vent line.

greengrass

since there is no need for a check valve even tho we just bought one what should i use it for? also what do you mean by put a loop in the vent line?

cheers for your help

DarZeelon

Joe,


Why would you need two clunks and lines?
What purpose does it serve?

I think with a short brass/aluminium fuel tube as a fill/return line, any engine would behave just the same.

Rupurt

Mr Grass, the reason for the loop is it prevents the fuel pouring out when the plane is inverted, for any reason. It will however still be able to start a siphon if you rotate the plane in the wrong way. It just makes life a little easier, altough it is far from perfect. Seeing as how you have the check valve maybe you could just use it instead, but you will then need a way to let the air out of the tank when you fill it, once you have it all in front of you it should make sense.

good luck.

JoeAirPort

My Feedback: (41)

It empties my tank until there are only drops left. That's why I like the clunk.

greengrass

ok maybe i when i fill the plane i will have it so i take the vent off then put it on once its filled? also where on the back plate should i
tap it for the nipple thing

JoeAirPort

My Feedback: (41)

You need a separate fill line, the vent will be the overflow. Look at the diagram in post #8 above. That's how I plumbed mine, works great. You use a fuel dot on the fill line. Just remove the fuel dot and fuel it up. When fuel runs out the vent line, it's full.

You need a three line tank.

sport10

It is not possible for the fuel to pour out of the overflow vent when the engine is running. There is airflow going into the tank via the vent tube while the pump is working because of the vaccum created in the tank by the pump. The fuel is not going to run out the vent against this flow of air. The only time fuel can run out of the vent tube is when the engine is off and both the vent line and fuel supply line are both open to air. It is very similar to putting a straw in water and putting your thumb over the end. Along as your thumb is sealing the end of the straw the liquid will not come out. Remove your thumb and it all comes out. Same principle. The best way is to leave the vent line open to the air. No check valve required. All the bypass loop does is relieve the pressure on the needle valve by returning it back to the fuel tank.

JoeAirPort

My Feedback: (41)

Mine doesn't leak out the vent and I have no loop. The fuel economy is right where it should be so there's no way the fuel is leaking out or I'd be landing alot sooner. Also I even tilted the plane forward on the ground while the engine was off, no leaking at all.

Rupurt

Mine pours fuel out the vent line if I am not careful(without the engine running). thats why I suggested that, if you don't have a problem no need to worry. BTW I have a 25cc weedie in a plane very similar arrangement with the pumped carb and I have the same problem

sport10

I have mine also plumbed without the bypass and it does not leak. It only leaks when I fuel the plane.

JoeAirPort

My Feedback: (41)

When you think about it you need another opening in the tank for the fuel to leak out of the vent unless you squeeze the tank. It would drip very slowly but there's no good path of flow. I'm not saying it can't happen just that there's not a really good path of flow out the vent.

Rupurt

Joe I get what you saying and I agree
I checked today, the vent pours for a bit and stops after a little while(probably the tank deforming slightly under the vucuum caused by the weight of the fuel), I am not using a bypass loop. The loop I was refering to is in the vent tube, I think you got that though. The trouble is it still makes a bit of a mess and the loop helps prevent this. What I said in post 15 is incorrect, It probably won't start a syphon as there isn't enough air getting into the tank, but before I put the pump on it would. [8D]

DarZeelon

The purpose of the bypass loop is to put fuel, with hardly any pressure, at the disposal of the carburettor, in its closest vicinity.

Fuel is constantly pumped into the last inch of the fuel line, between the far-end T-fitting and the carburettor nipple, where the carburettor can easily suck it, without having to draw it through the entire length of the fuel line.

Fuel is not fed under pressure, due to the bypass venting nearly all of it, so a regular suction carburettor will do and the close proximity of available fuel makes the carburettor's suction choir 'a piece of cake'.