Daelim Besbi scooter- fuel pump not working

[cyian]

Hi,

I have a Daelim Besbi scooter. It will not start. A mechanic just had a look, and found there is no fuel coming from the fuel tank into the carburettor.

I'm wondering if it is possible to repair the fuel pump (instead of replacing it).

I can't find much info on the part itself- is it actually a fuel pump?

Does anyone have suggestions on pulling it apart/fixing?

(the "fuel pump" thing is circled in red)

https://i.ibb.co/wgbMwtC/IMG-8823-2.jpg

https://i.ibb.co/stfsJy6/IMG-8826.jpg[/img]

A stock photo of it:
https://i.ibb.co/1JqWRKk/Screen-Shot-2021-02-08-at-4-38-04-pm.jpg

[oilrag]

Yes that is the fuel pump. If you search Youtube for vacuum fuel pump or impulse fuel pump you will see how it works. Basically it has diaphragm and two check valves. When the engine runs the piston moves up and down in the cylinder and that cause the diaphragm in the fuel pump to deflect left and right. When it deflect right it creates a vacuum in the pump and draws fuel in past one check valve. When it deflects left it pushes the fuel out the other check valve. They fail because the diaphragms go hard or the check valves leak. The only way to repair it is with new diaphragms and check valves. They come in a rebuild kit.

Before you rebuild it take the hoses off one at a time. If you put your finger over one of the hoses and crank the engine you should feel it sucking your finger. That is the vacuum line.

The other hose will come from the petrol tank. Make sure fuel is coming out of that. If the fuel filter is blocked no fuel will come out. There's usually a filter in the fuel line and one in the tank. Make sure the filters are clean.

The third hose goes to the carb. If you pour fuel directly in there the engine should start.

[WD Forte]

why not just buy one of these and bung it on

https://www.ebay.co.uk/itm/Vacuum-Fuel-Pump-Petcock-Petrol-Gas-Carburettor-Scooter-Quad-Bike-ATV-Buggy/163488118434?hash=item2610a6b6a2:g:3Q0AAOSwzHdf5nwX
____________________
bikers smell of wee

[cyian]

[oilrag]

Yes that's right fuel won't come out unless you can get the fuel line lower than the tank. All I was trying to say is make sure that the fuel filter or fuel line isn't blocked before blaming the pump. It could also be a trapped breather line for the fuel tank.

Any similar sized fuel pump from a 125 should work fine.

[bikenut]

I see the pictures have changed, pity cos they showed a really well maintained bike 😁

Is there a rag under the saddle blocking the fuel tank vent perhaps ?

It does happen dudes.

One pipe will come from the tank, another to the carb, and the smaller diameter one to the engine for vacuum.

The tap/pump unit may well have arrows on it to indicate flow etc..

A leak on any pipe really can cause malfunction.

Mark the pipes with different cable ties or tape before you remove them, and either note down or take pictures of locations.

Since you "can't ? " Figure out which pipe goes where, should you take the Carb off for cleaning ?

To clean carb, first clean carbs outside ! All that dust and muck etc..

When u done that, start to clean the carb at the fuel filler cap.

Avoid taking that rusty chrome carb "lid" off , there is a spring and rubber diaphragm underneath.

If that diaphragm is punctured, the bike will run and rev, but will not be able to pull the skin off a rice pudding !!

To test diaphragm with carb on the engine, remove hose from carb to airbox, run engine a rev, and see the "piston and needle " rise.

Get exploded view of the carb to help you.

Take your time, slow and steady as you go, take pictures and mark stuff so you know where stuff goes back, and enjoy.

This task is not a race ! Enjoy.
____________________
nuts about bikes

[WD Forte]

Here's what the pipes do
Any 3 port vacuum operated pump will do and fitting a new filter
would be good practise.
Good, sound, non leaky fittings are vital for the pump to operate properly

https://imgur.com/iycD55q.jpg
____________________
bikers smell of wee

[cyian]

Oh dear, the pump linked on eBay is about 50% smaller than my existing one...

Also, the pipes aren’t as tight on the outlets.

Does this mean it’s the wrong pump?

Is there a outlet size of something I need to look for?

Is this a better fit? Seems larger:

https://www.ebay.com.au/itm/253641759434

[WD Forte]

Hmm, tricky to estimate sizes in a pic with nothing to reference it to

If you've already bought that small one, one trick/workaround/bodge
I've done at times to get up and running ASAP for test purposes,
is to sleeve the nozzles with heat shrink or tube to get a snugger fit
for the hoses.
This can work for long periods as long as the sleeves are petrol resistant
If not, or unsure, best just do it for testing/checking it runs OK
then fit more appropriate kit fairly soon after for peace of mind

fuel pipes and nozzles usually come in 6/7/8mm sizes for bikes
you can force a 6 on a 7, even an 8 with flexible pipe
but fitting 7 or 8 on a 6mm will be loose hence sleeving

Edit: It looks like yours has a GY6 engine so pumps with that in the description have a good chance of fitting.
____________________
bikers smell of wee

[cyian]

[WD Forte]

From what I see in the pic I have is

Outlet 2 is fuel in from tank via filter
Outlet 3 is fuel out to carby
Outlet 1 is vac line from manifold
____________________
bikers smell of wee

[bikenut]

Are there any arrows on the unit to indicate flow ?

Is the unit an actual pump or just a vac operated "tap".

For it to be a pump, there will be check valves somewhere, as prior mentioned.

I would get an oe unit, a besbi part.

If an oe besbi part is not available, have a rethink.

I would have thought any check valves would be in the oe unit, but you never know.

So, what to do?

Do you have some clean hose and an assistant, or a vac pump of some sort ?

With clean hoses, fit them to the stubs.

Your assistant "sucks" on the vac stud whilst you blow down one of the other.stubs, to establish if it's just a tap, or a pump with check valves.

I would imaging the vac stub is the top one, with the fuel stubs "below" the vac half of the unit, with the vac diaphragm ( sprung loaded) in the top half.

With the vac stub sucked, can you blow thru one of fuel stubs, can you also suck thru the same fuel stub ?

If you can blow and suck thru the same fuel stub whilst your assistant sucks on the vac stub, the unit is a tap only I would think.

Just get an oe part, much easier.

Feedback, how did it do ?

While your doing all this sucking and blowing, remove the fuel pipe to the bikes pump. You say fuel will not flow due to gravity/Syphon.

If you now blow into the tank to slightly pressure ise the tank, does fuel flow now ?

I assume the tank has fuel ?

Does the tank have a "reserve fuel" function ?
____________________
nuts about bikes

[cyian]

Thanks for the replies again. I returned that pump, and bought this one (as it looks, at least, like a much better size)

Can someone tell me which pipes go where for this model?

[WD Forte]

I reckon its

2 to vac port on inlet manifold
3 inlet from tank/filter
1 outlet to carb
____________________
bikers smell of wee

[bikenut]

I would agree with above but post a picture of the other side, this has 2 diaphragms so is probably a pump rather than a tap.

Check for one way or check valves, see hose and assistant method...

Picture of other side please...
____________________
nuts about bikes

[bikenut]

I/we realise why you're asking.....your a newbie to this stuff....so one step at a time.

Fuel problem so let's start at the tank.

The tank will have a vent, a small hole possibly, is the vent clear or blocked, it may be in the fuel filler cap.

Anyways, the fuel pipe from the fuel tank to the "oe pump" on the bike, at the tank, does it connect at the bottom of the tank or at the top ?

Oe means original equipment, the bike pump etc..

Did you remove the tank fuel pipe at the pump and slightly pressurise the fuel tank, and did fuel flow out from the disconnected pipe ? Yes or no ?

Let's establish this first else go around in circles.

Note, when the time comes to start the engine, it will take some time for the fuel pump to pump fuel to the carb and fill it for the engine to run.
The engine whizzing over causes the pump to pump, any air leaks will not allow the pump to pump. A fully charged battery will help, when I he time comes. Remember this note.
____________________
nuts about bikes

[bikenut]

How you getting on with your bike, any progress ?
____________________
nuts about bikes

[Robby]

Try getting on to the supplier and buying the right part, then fitting it how it was fitted before.

Random cheap ebay parts are a bit hit and miss. Fine if you know what you're doing, but if you just want to replace the part and know it will work, buy the genuine part.

[xX-Alex-Xx]

On the other side, are there any markings showing fuel flow direction?
____________________
DILLIGAF

[xX-Alex-Xx]

[bikenut]

[cyian]

I’ve attached the new pump but still no luck.

I think I’m missing the basics- when i start the engine, should fuel move up from the tank without the pump? Or should the pump create suction?

Have i got the tubes correctly plugged in?

https://i.ibb.co/wwqg0R2/47148-F6-E-9-F96-4-F3-F-85-D3-BA7-AD67-B05-D4.jpg

Also, I’ve removed the fuel filter but again no fuel comes up when i start the ignition

https://i.ibb.co/6yqky8M/EE2-BA9-DB-264-E-49-C6-8-D58-B455513222-C0.jpg

[cyian]

[WD Forte]

It looks to me like you have the carb and tank pipes reversed
Arrow pointing in to pump is usually pipe from the tank
Arrow pointing out from the pump is the pipe outlet to the carb
____________________
bikers smell of wee

[cyian]