Husqy 55 Rancher just will not run?

[Mongo]

A friend of mine has a Husqvarna 55 Rancher that he couldn't get started and wanted me to take look at it. I got it started but couldn't keep it running for more than 3 seconds. I tinkered with the carb settings and got it to idle but it wouldn't rev without stalling. Since then I've rebuilt the carb, installed new boot and grommet between the back plate and cylinder, new back plated because plastic threads were stripped, new fuel line and filter and new spark plug. It will crank and idle fine and may rev up to full throttle once but after that it will only idle. Just as soon as I touch the trigger it acts like I just jambed a cork into the muffler hole. By the way, I took the spark arrester screen out just for kicks and it didn't change a thing. If anyone has any suggestions for me I would be grateful. Otherwise, I'm going to through it out in the driveway and run over it a few times. Thanks ahead!

 

[314epw]

won't run

Do you have fresh fuel?The 4 things you need is air,fuel,spark, and compression.Compression feel good?Change the plug again for the hell of it.
Ed

 

[GitWood]

Although I haven't seen it on a saw, I have experienced such behavior from a bad coil on both a 2-stroke ATV and a boat motor. The only way that I know to really test for that is to put on a new coil. Maybe some of the experts here have a better way. I'd like to know myself for future reference.

 

[stckciv]

Possibly may need a new carb. I have had this happen before and tried another carb and it worked fine.

Is the exhaust port clogged? You just mentioned taking out the screen not the whole muffler.

Keep us updated on what it turns out to be.

 

[Mongo]

Fixed it!

I figured out what my problem was. Apparently I was taking a nap or something when I was rebuilding the carb. I installed the gaskets and diaphragms just like I had taken them out but the person that did it just before me put them in backwards. What I mean by that is.... if you are looking at the carb right side up... on the top is a cap then a diaphragm, gasket, body, diaphragm, gasket, bottom cap. I had the bottom gasket and diaphragm switched. If the gaskets aren't in the right place they can't function properly. Apparently it would pump just enough gas to get it started and idle but would suck the carburetor dry just as soon as I would touch the gas. An experienced mechanic would have caught that before having replaced every other part except the bar and chain. But hey, it should run for a while now. Thanks for the input!