272 help needed

[MinnesotaJon]

I tore apart a 272 and went through it, fun little first time project. I put new seals bottom end and carb seals. a new top end and piston. Got it all back together and have been idling it to break it in and noticed it won’t run pto side up. It runs good and idles forever in every other position. But when I turn it pto side up it does after like six seconds. It just slows down and dies doesn’t speed away like going lean. The fuel line is pliable and the filter looks clean that’s all I can think it could be. I sprayed carb cleaner every where and it doesn’t change. I don’t have the stuff to vacuum and pressure test. Looking for suggestions. I ordered a fuel line and filter to see.

 

[svk]

Clear fuel lines or black?

 

[RED-85-Z51]

Could be pooling fuel. Pull the plug immediately after it dies...see if it's wet

Sent from my SM-G996U using Tapatalk

 

[MinnesotaJon]

black fuel lines.
what is pooling fuel and how do you fix it.

 

[hotshot]

PTO side up can move the fuel completely away from the pickup/weighted filter, leaving it “up in the air” inside the tank, plus it’s not a normal cutting position.

Is the gas tank completely full of fuel?

 

[drf255]

I’d Vac/pressure check it. Unless the filter and line are coming out of the mix, it’s gonna be the PTO side seal that starts sucking air and isn’t getting wet. That’s usually the culprit if a saw dies in a different position. Check your intake block and gaskets as well fuel pooling can do it, and if it’s anything like the 262, having the gaskets wrong can cause issues as well.

 

[MinnesotaJon]

I am going to check everything over again. If it was a crank seal would it go lean and race away and die?

 

[Johnmn]

On the pto side the seal is installed in the oil pump, the depth of the seal is important but also on the back of the oil pump there is an o-ring. Did you replace the o-ring when you did the seal?

 

[MinnesotaJon]

I didn’t know there was an oring when I ordered parts so I didn’t. I will replace that when I am in there. Should the seal be set as shallow in the oiler as possible to get it on the crank as much as possible? Should I just get a new AM oiler and try the whole assembly?

 

[Johnmn]

I didn’t know there was an oring when I ordered parts so I didn’t. I will replace that when I am in there. Should the seal be set as shallow in the oiler as possible to get it on the crank as much as possible? Should I just get a new AM oiler and try the whole assembly?

No don't get an AM oiler. If you look at the back of the oiler there is an o-ring and if you look at the seal it should stick out oh maybe 1/16 or so. I should have several I'll grab a picture.

 

[Johnmn]

This shows the o-ring and the depth of the seal in relation to the back of the oiler.

 

[MinnesotaJon]

Thank you! I am going to tear that apart tonight and see if I can find an oring on the way home tomorrow at Napa or hardware store. I’ll check the seal depth then too.

 

[Johnmn]

It's a little bit of an odd duck 29.1mm x 1.6mm is the size

Thank you! I am going to tear that apart tonight and see if I can find an oring on the way home tomorrow at Napa or hardware store. I’ll check the seal depth then too.

 

[MinnesotaJon]

My seal was not that deep and the oring looks questionable. So I ordered a new seal, oring, fuel line, and filter. Hopefully with all that this will be fixed. I’ll update on what happens.

 

[MinnesotaJon]

I put the new seal, oring, fuel line and filter in. Son of a gun it still does it. It runs good idles good holds a tune I don’t get it. I guess it just won’t get a wrap handle lol.

 

[Johnmn]

Either myself or @mortalitool tool would be willing to take a look at it. We are both in Minnesota but we are 2+ hours apart.

 

[rupedoggy]

There you go. If you don't take advantage of this offer.........Quit crying

 

[MinnesotaJon]

Either myself or @mortalitool tool would be willing to take a look at it. We are both in Minnesota but we are 2+ hours apart.

I might have to take you up on that offer. I took it out and put it in wood today to see what it would do. Everything works like it should except turning it pto side up.

 

[MinnesotaJon]

I don’t know if anyone is following my saga along. I got a mityvac tester, cut up some rubber and aluminum plates. Sucked her down to 15hg let it sit five minutes came back spun the crank slow for two minutes. Stayed put so I put pressure to it 10psi same thing. I am down to fuel issue some how maybe carb issue. Still playing having and having fun!

 

[Johnmn]

7 is all that's needed for a pressure/vac test. Also check to make sure one of the gaskets on either side of the intake block hasn't partially blocked the pulse port. I have had to enlarge the holes that line up with that port in the past. From there I move to the fuel system.