Jonsered 451 died and won't restart

[LivinTheDream]

Rebuilt the carb on Jonsered 451EV last year and it's been running awesome. But last time I used it, I put it down idling after cutting wood and while it was idling it died. Kind of acted like it ran out of fuel. So I filled it (it wasn't empty) and it still wouldn't start. Took apart the metering side of carb and it seemed dry (ish). Emptied the fuel tank, removed the carb, and thought I'd make sure the fuel line hadn't collapsed or clogged. Blew through it and couldn't get it to flow air...but when I took my mouth off it, it sprayed me with fuel. Rookie mistake (gas cap was still on). Removed the gas cap and it can flow air through it now. Thought I'd check the vent line...but HOW do I do that? As shown in photos, my finger is pointing towards the vent line. It comes up through the housing from the tank, snakes under where the carb mounts, and then exits through a "bulkhead" and disappears under the fins of the motor.

 

[Cantdog]

Do you have spark?

 

[LivinTheDream]

Do you have spark?

yes, spark is good.
Seems like lack of fuel. Would like to rule out a clogged fuel tank vent, but I can't find the end of it; seems to disappear under the engine. Found part on line; looks like this:

 

[Cantdog]

yes, spark is good.
Seems like lack of fuel. Would like to rule out a clogged fuel tank vent, but I can't find the end of it; seems to disappear under the engine. Found part on line; looks like this:
View attachment 1069734

Yes that will pull right out of the hole it's in.......sintered bronze filter in the end.....

Stiil may be spark.....coils heat up and break down then act normal when cooled.

 

[JS Gear Work]

On my spare 451E crank cases I found a check ball in a metal tube at the end of the line. Cleared it n reused it. I removed the bullet filter on the other end of the vent line n made my own screen with a wire mesh pipe screen soldered to a brass fitting tube.…I also found a crack on the vent hose. It was bubbling air n fuel out of the fuel chamber where the hose enters the chamber. The bullet Filter was restricting air to the fuel chamber causing pressure to build n leaking out the hose cracked. Hope that helps.

 

[JS Gear Work]

I forgot the end of the hose of vent hose is located inside where the brake/centrifugal clutch drum. You will have to remove the bar to get to that drum.

 

[LivinTheDream]

I forgot the end of the hose of vent hose is located inside where the brake/centrifugal clutch drum. You will have to remove the bar to get to that drum.

Thanks. The bar is off, so I'll take another look.

 

[pioneerguy600]

Do you have spark?

Your favorite series ,Robin!

 

[LivinTheDream]

Well, I found where the vent tube ends. Removed clutch drum to find it. However, it doesn't look like what's listed in the parts diagrams. There's no sintered brass plug in the end -- there's just the tube. See photo at 11:00 position.
So I've had the saw for 30 years, and as far as I know it's always been this way. I may just blow some compressed air backwards into the tank thru the carb inlet hose (with filter removed from end) to pressurize the tank (with the fuel cap on) and see if any junk blows out the vent tube.

 

[Cantdog]

Your favorite series ,Robin!

LOL!! Actually the 451 is a great little saw.....a true Jonsereds.....it's the 5XX series I can't hack...other than the 590...another great saw....

 

[Cantdog]

The filter probably fell out sometime in the last 40 years.....

 

[pioneerguy600]

LOL!! Actually the 451 is a great little saw.....a true Jonsereds.....it's the 5XX series I can't hack...other than the 590...another great saw....

I could see it has some metal showing, so not all plastic.

 

[Cantdog]

I could see it has some metal showing, so not all plastic.

Pretty much just the top cover.... They were designed as a light, nimble, high speed dedicated limbing saw.....not even a place to mount dawgs....the 70E and the 451 were the only Jonsereds that came set up to run the NordFella......pro saw for sure....

 

[LivinTheDream]

Update: It's running good again! Started on first pull, runs, and idles.
That's after I disassembled the carb, cleaned out all the passages with compressed air, reassembled (with existing gaskets), blew out the intake fuel line, blew compressed air into the gas tank via the fuel line (with gas cap on)...but didn't seem to get anything out of the vent line, installed new inlet fuel filter. So I'm not sure what the problem was, and I'm still not sure the vent line is working the way it's supposed to. But I'll accept as one of life's mysteries.

 

[JS Gear Work]

I believe the check ball on the inside of the fuel chamber is working if it has one on the inside end of the vent hose. You may have had a plugged up fuel filter. I think if you didn’t have the check valve in the hose it would leak where it exits. It let’s air in n not fuel out the vent.