Honda GX35 Brush Cutter won't run

[GrahamGKD]

Hi Folks,
I can't get my brush cutter to run - it will fire and run for 3 - 10 seconds occasionally but that's it. I have a good spark. The compression seems fine. I have stripped the carb many times and have blown everything out. I can see no damage to either of diaphragms. There is a tiny fuel filter above the inlet jet - I tried cleaning it and I also then tried firing it up with this tiny filter removed altogether. If I could see where to get one of these filters I would buy a replacement but even the carb service kits seem to miss this part out (from looking at the pictures on ebay). At the moment I'm favoring a replacement carb for about £23 but they are not genuine for that price - might that be a bad move I wonder?

Oh, and the fuel is brand new.

Any suggestions please?

Graham.

 

[Wendelspanswick]

My first point of call is always to change the plug, especially on small engines. They can test OK out of the engine but fail once under load or hot. I gained a whacker plate this way, supposedly it had had loads done to it but no one bothered to change the plug as it had a good spark when held against the casing.
It will only cost you a couple of quid to substitute as well.

 

[GrahamGKD]

Hmm, I did wonder about that but dismissed it - I'll get another sparkplug in the first instance then. Thanks. Graham.

 

[Rocketman]

Funny enough my 4 stroke Honda strimmer wouldn't start last weekend either. Pretty sure it's dead petrol in my case but had no time to go get some. I agree as you have ruled out petrol try a spark plug now.

 

[p0689109]

Did you leave old petrol in it(I assume it is 4 stroke). If so it should come good after a sonic clean rather than buying a new carb.

 

[GrahamGKD]

Yes, there was old (but not very old) petrol in it and it is a 4 stroke. I don't have a sonic cleaner but I have blown and poked every hole / jet /aperture in the carb?

 

[brewdexta]

my honda strimmer had a similar issue and a new carb did it (didn't try sonic cleaning though). However it now cuts out every few minutes, take the top off the fuel filler and off it goes again so a fuel tank breather problem. I haven't had chance to look into it to see its blocked or just a crap design.

 

[wristpin]

If it has a weighted fuel filter on the end of the pick-up hose in the tank check that it's not "solid" with dirt. They often are and just don't let enough fuel through.

 

[GrahamGKD]

I think the fuel supply from the tank is OK because the little priming pump pumps fuel up and back down the return freely enough.

 

[roofman]

Iff its a diagrahm<<(spell) carb which 99% are then under the rubber seal there is a tiny needle valve which can stick or have a bit of dirt in it...check that 1st before you start spending

 

[GrahamGKD]

Yes, it does have a valve operated by the diaphragm but that seems to be OK.

 

[Turbo]

As others have said, try a new plug. All small engines should have a new plug at the start of the season.

There's a simple way of sorting whether it's a spark or fuel problem. Take off the air filter and spray a bit of WD40 into the carb & try to start it. Engines run very well on WD40 & if it starts then you have a fuel problem.

The current formulation of unleaded petrol has a short shelf life and will go dead in a month. If you leave it in a carb over the winter it gums up the innards and often no amount of manual cleaning will move it. You could try spraying carb cleaner through the ports in the carb. Modern small engines run on tight tolerances on the fuelling side to comply with emissions and it takes very little to affect them. Often the only way to sort it is with an ultrasonic cleaner but sometimes even that doesn't work & you have to buy a new carb.

If you're going to store any small engine for more than a month its very important to drain the fuel tank then run the engine until the carb is empty. If you want to be thorough you could strip the carb & blow out any remaining fuel.

Those 4 stroke honda strimmers are a pain to keep running well, give me a 2 stroke any day. Unfortunately thats the way things are going as they're trying to ban 2 stroke engines because of emissions.

 

[p0689109]

No amount of poking helps, sonic cleaning is the only way to get it cleaned. Firms like garden maintenance eqpt dealers normally do the service.

 

[GrahamGKD]

Hoorah - it was the plug - thanks all, especially Wendelspanswick. The thing has been doing my head in over the last couple of days of fiddling (on and off) so I am relieved to have solved it. I had dismissed anything to do with the ignition because I was seeing a good spark with the plug out. I won't be making that mistake again anytime soon!

My local garden place wanted £100 to service it (they charged me over £7 for the spark plug). I get the feeling they might be an expensive place? Anyway, I'm not in the habit of paying anyone anything to do something I can do myself, especially now I am retired.

BTW - I tried the WD40 trick as suggested by Turbo (before I trotted off to buy the plug) - it ran for a while the first time but then subsequent applications of WD40 didn't seem to do anything?

Thanks Again Everyone :-)

Graham.

 

[Turbo]

they charged me over £7 for the spark plug

Place I worked only charged £3 for a plug & £15 for a basic service. £100 would be half price of a new one!

If a machine didn't start after being filled with fresh fuel & a new plug the WD40 trick was next to check where the problem was.

 

[GrahamGKD]

£100 would be half price of a new one!

Yes, that's what I was thinking, especially when there was no guarantee it would work after the service.

If a machine didn't start after being filled with fresh fuel & a new plug the WD40 trick was next to check where the problem was.

Yes, it is a good test - I will remember that. Thanks.

 

[the snooper]

ive got a wacker in the workshop that wouldn't start, same type of carb I striped it a few times and never saw a problem, then I bought the service kit 12 quid I think and it would start up after I fitted it, I didn't start up great but at least it did, its just sat there ever since. I forgot all about it

 

[GrahamGKD]

....with the new spark plug in it my brushcutter starts and runs better than it has for the last couple of seasons! I might just buy one of those carb service kits as well because I have lost one of the fuel filters out of the carb.