670 champ or super??????

[JONSEREDFAN6069]

670 champ or super surging

my 670 champ or super serial number 8380229 surges when under a heavy pull, wet maple about 40 inches across running a 36 inch bar with a brand new stihl chain, just started. could this be a dirty fuel filter or the high low adjustments out? air filter just cleaned, was running great.

 

[Metals406]

Surging like lack of fuel? Lot's of things can cause surging. Remember fuel and fire, it has to be one of the two. Check to see if all lines are tight and crack free, also free of obstructions. Fuel filter is one of the first things I'd check/change. My Jonny 670 was surging about three weeks ago... Changed the fuel filter... Problem solved.

 

[JONSEREDFAN6069]

fuel is full, fuel line seems to be a little squishy though, wonder if the pump is closing the line off? i will change the filter and the line and see. never seen a fuel line get that soft before.

 

[bama]

Also, check the wires if fuel filter doesn't do it. Could be an intermittent ground from a cracked wire.

 

[JONSEREDFAN6069]

:greenchainsaw: the other thing i forgot to mention, the muffler had the turn down off. attaches with two screws, my brother borrowed the saw and put it back on, would this cause this problem? seems like a stupid question i know but would it cause too much back pressure? and what are your views on muffler mods and what is needed to be done after modded?

 

[Metals406]

fuel is full, fuel line seems to be a little squishy though, wonder if the pump is closing the line off? i will change the filter and the line and see. never seen a fuel line get that soft before.

The guys at my local saw shops' are complaining about the ethanol in the fuel destroying lines and seals, and even linings in the black tanks on Honda motors...

 

[JONSEREDFAN6069]

is there a fuel line out there that resists the ethanol. i have on occasion ran bp race gas through her, wow what a difference but costly.

 

[Metals406]

:greenchainsaw: the other thing i forgot to mention, the muffler had the turn down off. attaches with two screws, my brother borrowed the saw and put it back on, would this cause this problem? seems like a stupid question i know but would it cause too much back pressure? and what are your views on muffler mods and what is needed to be done after modded?

Type in 'mod' in the search function... Be prepared for a lot of reading... But you'll get plenty of info on the subject.

Muffler mods' are like sechs... You'll wonder why you didn't do it before, and more often.

 

[Metals406]

is there a fuel line out there that resists the ethanol. i have on occasion ran bp race gas through her, wow what a difference but costly.

Yes, a lot of dudes are running AV gas to avoid the ethanol... Not really a cost issue if you think about the volume you purchase for a chainsaw... Hell, 10 gallons would last a while under non-commercial apps.

No fuel line that is alcohol resistant to my knowledge... Unless they start making them out of hemp.