Help! Rough running.

[jesterr6216]

Hi guys. Brand new to this site and looking for some help and guidance.

I have a Einhell BG PC 3735. We have a wood burner in the house so got the chainsaw to go out hunting and gathering logs for firewood. Very satisfying burning logs you have cut, chucked in back of Landrover, chopped and stacked.

Anyways. Was happlily cutting away the other day, chainsaw working great, when it started to run rough, revving high, then low. I stopped it to check the fuel level when I noticed the primer bulb had split (it was looking old yellow and brittle). With my basic knowledge of engines I thought that it must be letting air into the system, hence the revving, so order a new part and that should be it.

Ordered and fitted said new primer bulb, but still got problems.

From cold, turn it on, full choke, ten pumps of primer, pull cord and it starts fine, revs high (on full choke), drop it down to half choke, again runs fine, but then when I pull the throttle to drop it to normal revs it pretty much straight away starts labouring, low revs, then konks out. And that's it. Can't start it again till it's sat for a bit.

One thing I have noticed, is the primer bulb seems to be staying full of fuel even when it's been sat not used for days. I'm sure in the past this would be empty after the initial priming.

 

I'm handyish with stuff so will to try stripping down to fix things rather than just paying to have a man do it. Wondering if it might be the carbs/jets? Took the plastic air filter off, gave it a good clean and dried it off so it's not that.

 

Any help would be greatly appreciated.

 

Cheers

[billpierce]

did you def put the primer gaskets/diaphrams back on the right way/ or even back on? sorry to ask!

[jesterr6216]

There weren't any gaskets/diaphrams, it's just a clear bulb with a black plastic part which on the back of it has two tubes, onto which you stick the two pipes.

 

Got me thinking now, might have to double check the old part

[spudulike]

It is possible that air got in to the carb and made it run lean - I would whip the exhaust off and make sure the piston looks in good shape.

 

TBH, if you are serious about collecting wood, do yourself a favour and buy a saw manufactured by one of the pro manufacturers. Something like a Stihl MS210/230 or Husqvarna 345/350 would work well:thumbup:

[jesterr6216]

Cheers Spud, will have a look. And yes, a proper bit of kit like the ones you mention is on my christmas list.

[jesterr6216]

Afternoon gents. Short update. Spent the last 2 days stripping my saw right down. Took it all to bits. Couldn't see anything obvious. Put it all back together, and guess what, I think I may have kinda fixed it (accidentally!!!).

 

On full choke it didn't really want to start, but it kinda got there, got it on mid choke and left it running fast there, then the acid test, clicking the trigger and dropping it off mid choke to normal running, and it kept going!!! This is a plus. BUT. When I go to take my finger off the throttle, it dies.

 

So, thinking maybe the fuel filter in the fuel resevoir may have been blocked/stuck in a corner and not drawing and maybe me mucking about has resolved it. But now I have the issue of it not idling. I'm guessing I need to play about with the carb screws, need to find where they are!

 

Ehhhhh it's a joy!

[spudulike]

Afternoon gents. Short update. Spent the last 2 days stripping my saw right down. Took it all to bits. Couldn't see anything obvious. Put it all back together, and guess what, I think I may have kinda fixed it (accidentally!!!).

 

On full choke it didn't really want to start, but it kinda got there, got it on mid choke and left it running fast there, then the acid test, clicking the trigger and dropping it off mid choke to normal running, and it kept going!!! This is a plus. BUT. When I go to take my finger off the throttle, it dies.

 

So, thinking maybe the fuel filter in the fuel resevoir may have been blocked/stuck in a corner and not drawing and maybe me mucking about has resolved it. But now I have the issue of it not idling. I'm guessing I need to play about with the carb screws, need to find where they are!

 

Ehhhhh it's a joy!

 

These cheapo saws tend to need a bit of a retune at some stage in their lives, you may get away with just increasing the idle speed (big screw on its own) or tweaking the L screw - the one nearest the engine of the two small side by side ones.

 

You will probably find the screws have splined heads and will need a special tool to adjust them - that's life:thumbdown: the screws will only need adjusting if the saw isn't picking up well or not revving out OK.

[peatff]

Did you get a manual with it ? Pump the bulb then with the choke fully out just pull it over till it coughs, saws don't usually start on full choke. Then push the choke in to the fast idle position which actually puts the choke off but speeds tick over not half choke. If you are pulling it over more than a couple of times on full choke it is probably flooding a bit.

[Fredward]

Don't be too keen to adjust the high low screws as you run the risk of leaning it out and damaging the saw (if it runs), carb adjustments should be very minor, like 1/8 of a turn or something.

[jesterr6216]

Cheers guys, will try some very slight tuning adjustments