Could it be a leak?

[backwoodsman]

Hello,

I recently acquired an Echo 602. I was told it ran but the recoil was broken. I’ve since replaced the recoil and attempted a start. It started with gas in the carb but died immediately.

I’ve checked the L and H screw and they were both about a half turn out from their stops so I adjusted to a full turn out (not sure of the settings) and after a few more pulls it started but ran as though it was at 3/4 full throttle (little bit of revving room left) and dies after 5 or so seconds.

I tore the carb down, cleaned it out as there was a bit of mung in it and put it back together… seemed ok and the diaphragm was still supple. After putting it back together it’s having the same issue at various screw settings (anywhere from 1/2 turn out to 1.5 turns out). It’s tough to get it going and it screams for those 5 or so seconds.

Could this be an air leak? Or does anyone have any other suggestions?

Thanks!

 

[sean donato]

Sure sounds like an air leak. Pressure/vac test it and see what you find.

 

[grizz55chev]

Hello,

I recently acquired an Echo 602. I was told it ran but the recoil was broken. I’ve since replaced the recoil and attempted a start. It started with gas in the carb but died immediately.

I’ve checked the L and H screw and they were both about a half turn out from their stops so I adjusted to a full turn out (not sure of the settings) and after a few more pulls it started but ran as though it was at 3/4 full throttle (little bit of revving room left) and dies after 5 or so seconds.

I tore the carb down, cleaned it out as there was a bit of mung in it and put it back together… seemed ok and the diaphragm was still supple. After putting it back together it’s having the same issue at various screw settings (anywhere from 1/2 turn out to 1.5 turns out). It’s tough to get it going and it screams for those 5 or so seconds.

Could this be an air leak? Or does anyone have any other suggestions?

Thanks!

Fuel filter and line might be compromised, also check the impulse line.

 

[backwoodsman]

Thanks for the help guys! I’ll tear it down and have another go.

 

[Wood Doctor]

Thanks for the help guys! I’ll tear it down and have another go.

It may also be the carb's final fuel strainer (small round screen) is clogged up. I've run unto this before.

 

[PV Hiker]

As long as you are looking at things, see if the exhaust screen is blocked. Take the muffler off and see what the piston and cylinder wall looks like through the exhaust port.

 

[sean donato]

A blocked exhaust wouldn't cause an uncontrolled high idle speed. Also his lack of being able to tune the carb suggests a air leak. Even with a partially blocked fuel supply you should be able to get it to low idle. I went through that recently with my (dads) 026. Fired up and idled died off idle. Could make it gain rpm using the choke, but would die immediately when the choke was taken off. Impulse line it wouldn't run without some degree of choke being used. Won't hurt to look at them anyway, but an air leak would fit the symptoms best imo.

 

[PV Hiker]

@sean donato I agree... op needs to find the air leak as he mentioned it screams high rpm no matter what adjustments are made.

Vacuum and pressure test would be wise before spending money on a carb.

Since it is new saw to him and it screams high idle, looking at the piston through the exhaust port would further confirm the previous owner ran it with a air leak. After looking in exhaust port and Vacuum/pressure test all looks good, proceed putting money into carb repair..etc.

 

[backwoodsman]

I’ve inspected the intake and exhaust side of the piston/cylinder and they’re smooth and shiny. It doesn’t look as though it’s spent much of its life running too lean.

I’ll have another look at the spark arrestor. I’ll check the fuel line again, it’s old and lost its flexibility but I’ll try to make sure it’s not collapsing under load.

I’ll also do a compression test now but I don’t have a vacuum/pressure tester so I’ll spend a little more time on the carb making sure nothing got wedged between one of the reused gaskets.

I appreciate the input. Thanks.

 

[sean donato]

Full stop brother. Old and not flexible is asking for issues. Same as reusing the carb gaskets. If any of the rubber components are suspect, it's really time to consider replacing them. $50 or $100 worth of parts for preventative measure is cheaper then replacing the saw. (If it would even cost that. Carb kits, and fuel line is cheap.) A vac/pressure hand pump can be had off Amazon,evilbay, or even harbor freight at reasonable cost. You can fabricate everything else you need to block the exhaust and carb from an inner tube, old spark plug and a bit of brake line. Possibly some epoxy to cement the brake line in a gutted spark plug to hook up the tester.
Point being we have reasonable suspicion of what the issue is, so we need to test it appropriately.

 

[backwoodsman]

A vac/pressure hand pump can be had off Amazon,evilbay, or even harbor freight at reasonable cost.

I’m not even sure if it’s a runner so I was trying keep costs down but you’re right, $29 for a vac/press tester probably isn’t a bad investment… and I think I spent less than $10 on the last carb kit I bought.

Thanks

 

[sean donato]

It's one of those tools you don't know how handy it is till you got one, then you don't know how you lived without it. Great for bleeding brakes, carb work ect. Not ideal but they work for fluid extraction too. Better for smaller tanks, as a large tank would take forever but in a pinch.

 

[samaritan]

look at the intake boot real close, I'll bet it's torn.

 

[HarleyT]

You should go ahead and clean and adjust the points, see if it runs any better. It is probably long overdue.

 

[samaritan]

Sure sounds like an air leak. Pressure/vac test it and see what you find.

My saw did the same thing, one of the transfer case covers fell off

 

[Evan]

Like stihl 391?

 

[samaritan]

Like stihl 391?

Its an ms251c