Makita hedge trimmer not pumping fuel

[Burnerman]

Apologies, I can see the video but no sound, so I can’t tell how fast the machine is running.
There is a centrifugal clutch on the bottom of the engine, and the engine speed has to be fast enough for the thing to engage and move the blades.
As the blades moved before, there’s no reason for things to have changed.
Those two screws.....H is for high engine speed adjustment, L for low speed or idle adjustment. Let’s leave them for now.
Is the throttle trigger moving the arm on the top of the carb?
John

 

[I'm not a robot]

Sorry about that, I uploaded the wrong video

 

[Burnerman]

There’s something jamming the blades there..... anything stuck in there somewhere?
If you slacken the blade bolts off it will help things in the interim.
The next step is to take off the sole plate on the bottom of the machine, but first things first!
John

 

[I'm not a robot]

Just went to have another go and the bulb has split so now I need to buy a bulb, are they standard sizes?

 

[Burnerman]

Oh blimey, I think so.....
Is this what you need?

Makita EH561 EH450 HTB7600 CARBURETOR REPAIR SERVICE CARB KIT | eBay

Makita HTB7600. MAKITA,BHX2500CA,PB250 4,HTB7600. MAKITA,BBX7600, BHX2500CA, PB2504, EH450, H2500, CARBURETOR REPAIR SERVICE KIT. New carburetor rebuild kit for Ryobi. MAKITA,DBC260L. 1X DIAPHRAGM GASKET.

www.ebay.co.uk

John

 

[Burnerman]

Just a word of caution.....
This machine is now obsolete so careful what you spend......it's cost you little so far but lets find out why the blades are jammed!
John

 

[I'm not a robot]

Thanks

I saw that repair kit on eBay and decide that as it looks quite an in depth procedure to dismantle the whole carb then it might just be worth spending a couple of quid on a bulb as it seems to be a case of four screws off and back on, just need the right size.
Will take a measurement tomorrow and order one.

 

[Burnerman]

Good luck with the search.....you are right, four screws off and new bulb in.
No gaskets required but there is a chance that the carb may split itself so watch out for that.
John

 

[I'm not a robot]

Just fitted the new primer bulb and also the new air filter, tried the bulb a couple of times and noticed fuel dripping, it's coming from the shorter pipe were it enters the tank. The pipe is not quite thick enough it seems.
Anyway I thought I'd give the machine a go to see if it runs okay so I managed to get some fuel into the bulb and tried it, machine starts fine and seems to idle well but when I pull the throttle it instantly dies, every time.

I'm just wondering if I have fitted the fuel pipes correctly as I didn't really take note of how the original pipes were fitted, could I have possibly fitted the fuel filter onto the wrong pipe?
How do I know which pipe goes where?
Currently I have the pipe going from the bulb and into the top hole of the tank and right down to the bottom with the fuel filter connected to the other end, the shorter pipe goes from the right side of the carb and into the lower hole in the tank, is this correct?

Thanks

 

[Burnerman]

I think if the machine is starting and idling then the fuel pipe location must be correct.......presumably the new bulb fills with fuel and then returns the excess back to the tank?
Now it's experiment time......turn the screw marked H a quarter of a turn (no more) and see if the machine wants to speed up.......anticlockwise first, then back to where it was, then clockwise 1/4 turn.
Also, see if half choke has the same effect on the engine.
(clockwise weakens the mixture, anticlockwise enriches it......unfortunately the symptoms of both are much the same, engine wise)!
If you turn the screw marked L clockwise, the engine revs may speed up, but there won't be any power when the throttle trigger is pressed so it's anticlockwise with that one until the engine just starts to slow up.
John

 

[I'm not a robot]

Changed the fuel pipes around after watching a youtube video and it pumps correctly now so I did have them the wrong way round.

Started the machine and it was great for about 30 seconds, blades were running fast and freely and engine revving well then it died again, now it's doing the same.

So before I start with the adjustments do I need the engine running while doing it?

 

[Burnerman]

Every day is a school day! I must confess I haven’t tried that before.
Anyway, if it will run for 30 sec you can’t be far away.....go for gentle adjustments with the engine running.
John

 

[I'm not a robot]

Couldn't adjust while running as it kept cutting out, turned H screw a quarter turn a few times both ways and no change, turned L screw a quarter turn anticlockwise just once and result, it is running pretty good and blades seem great.

 

[Burnerman]

A great result and well done!
Nothing wrong with that machine - keep the blades oiled though.....grinding them to sharpen isn’t a diy thing.
John

 

[I'm not a robot]

A great result and well done!
Nothing wrong with that machine - keep the blades oiled though.....grinding them to sharpen isn’t a diy thing.
John

Thanks, I am please we got there and it only cost me £10.45 and I still have pipe, filter and a spare bulb so well worth the effort, also I learned a fair bit so chuffed about that too.

What oil do you recommend for the blades?