Any guesses on what might cause this

[GeorgiaVOL]

Recently got this saw running again. I rebuilt the carb, fired it up in a few pulls tuned it which was about 1 turn out each. Cut a few cookies, all was good. Next day warmed it up, cut a couple more still was good. So I grabbed the camera to shoot a video and this happened. Cut well until the end and then it suddenly started raceing. I pulled the choke out to stop it. Now it restarts ok but anything over half throttle and it does it again.

 

[Mattyo]

Too much air....or too little fuel.

 

[GeorgiaVOL]

Yep, I got that part. Talked with another member, going to replace fuel line and vent and see If that helps.

 

[merc_man]

Air leak? Pressure an vac test it.

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[GeorgiaVOL]

Unfortunately I don't have those tools. They would be helpful. I will have to look at investing in them.

 

[merc_man]

If you have an air comoressor you can drop the psi down and pressure test it.

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[Stump Shot]

I'll wager a dollar that the oil pump side seal is leaking.

 

[Mattyo]

Hit the high points. Fuel line is a good idea...and filter. If those crank seals haven't been changed out it might be time. What year is the saw?

Without diagnostic tools sometimes you can play a little "parts darts" throw some seals at it

 

[GeorgiaVOL]

Not sure the year but here is the tag. Anyone change seals on one of these? Are they difficult to change?

 

[backhoelover]

@Definitive Dave can get you everything you need at a awesome price

 

[Redfin]

Check your intake block for cracks.

 

[GeorgiaVOL]

That would be awesome, I have had zero luck with a tank vent.

 

[Mattyo]

If you open the gas tank...and close it...and it runs perfect for 5 minutes....it's the vent.


Unlikely you have a vent issue.

Keep in mind...a top reason for bad seals....bad bearings.

 

[Mattyo]

Btw...nice suggestion by redfin.... cracked block might do it too...but I'm betting on old rubber seals

 

[GeorgiaVOL]

It leaks fuel at the vent, so I know I need one of those. My guess on the fuel line was that at high demand it pinches the line leaning it out.

 

[GeorgiaVOL]

I do appreciate the suggestions. I will be checking them as I go.

 

[Chainsaw Jim]

Every time this happens to me it's the carb mount screws rattling loose. It runs great then second time around it starts losing power under load followed by lean racing or just completely erratic idling. You gotta loctite the chit out of those screws. It never hurts to resurface the intake block if there is the slightest warpage or friction damage.

 

[jb-chainsaws]

Every time this happens to me it's the carb mount screws rattling loose. It runs great then second time around it starts losing power under load followed by lean racing or just completely erratic idling. You gotta loctite the chit out of those screws. It never hurts to resurface the intake block if there is the slightest warpage or friction damage.

Have to do this on my milling 090, those little suckers won't stay tight for chit! Flatten the block on some emery on a glass plate then loctite the nuts

 

[XP_Slinger]

Lots of good suggestions. If you don't find anything my input is make sure the butterfly screw is tight in your carb. I had a loose one that would now allow the throttle to return to idle because the butterfly was getting jammed in the carb bore.

 

[mdavlee]

Can of WD40 can find a lot of leaks. Get it running and spray around the intake parts