Murray MS9900 Leaf Blower

[patrickw7843]

I have a Murray MS9900 leaf blower that had me stuck. Primer bulb and fuel line were cracked due to age. I replaced both, and tried to start. After pulling about 15-20 times, it fired up and ran for maybe 30 seconds before dying. I figured it wasn't getting gas, so I pulled the carburetor and cleaned it. Reinstalled and pulled, still won't start. Replaced the fuel filter and spark plug. Still won't start. Wondering where to look next.

 

[Bange]

When removing the spark plug, how was it?
Wet or dry?
If it is wet, the engine is drunk with excess fuel > check the tightness of the stuck inlet valve/float or the spark may not be coming out > check the spark plug wire is broken or leaking spark to ground, coil open or shorted, switch on /off, magnetic sensor proximity...
If completely drained, fuel may not be going to carburetor > check float stuck closed or clogging.

 

[StarTech]

ZAMA C1U-P27 (MTD 753-06288) Simple Start carburetor. A royal to repair. Most times you end up replacing the carb.

 

[patrickw7843]

When removing the spark plug, how was it?
Wet or dry?
If it is wet, the engine is drunk with excess fuel > check the tightness of the stuck inlet valve/float or the spark may not be coming out > check the spark plug wire is broken or leaking spark to ground, coil open or shorted, switch on /off, magnetic sensor proximity...
If completely drained, fuel may not be going to carburetor > check float stuck closed or clogging.

It was dry when I first started. After pulling quite a few times with it choked, it was wet. I'm going to replace the coil, and hopefully that's my problem.

 

[PTmowerMech]

It was dry when I first started. After pulling quite a few times with it choked, it was wet. I'm going to replace the coil, and hopefully that's my problem.

Replacing everything without knowing what's wrong can get expensive. Does it have spark?

If it's flooding out you can pull plug and dry out the plug, slowing pull the starter rope a few times. Reinsert the plug and try it again. Or open the choke, with full throttle, pull on the pull rope until it cranks. If any time during all that pulling, it tries to crank, more than likely you're getting spark. And no need to change the coil. And that only leaves the carburetor as the culprit.
Did you check the compression? It's a good idea, when you remove the spark plug, to look into the cylinder, with the piston down all the way, and see if anything is scored. Also remove the muffler and look to see if there's anything scored, or any of the ports are clogged. With the muffler off, also check to see if the muffler screen is clogged.

 

[patrickw7843]

Replacing everything without knowing what's wrong can get expensive. Does it have spark?

If it's flooding out you can pull plug and dry out the plug, slowing pull the starter rope a few times. Reinsert the plug and try it again. Or open the choke, with full throttle, pull on the pull rope until it cranks. If any time during all that pulling, it tries to crank, more than likely you're getting spark. And no need to change the coil. And that only leaves the carburetor as the culprit.
Did you check the compression? It's a good idea, when you remove the spark plug, to look into the cylinder, with the piston down all the way, and see if anything is scored. Also remove the muffler and look to see if there's anything scored, or any of the ports are clogged. With the muffler off, also check to see if the muffler screen is clogged.

It ended up being a stuck piston ring that didn't allow for good compression. I don't know why, but it didn't occur to me to check the compression.

 

[PTmowerMech]

It ended up being a stuck piston ring that didn't allow for good compression. I don't know why, but it didn't occur to me to check the compression.

I've done a rebuild on one like that once. Replaced the rings. Thanks to @bertsmobile1 , who turned me onto Aliaba (one what ever the name of that company was) It was pretty easy. It took them forever to send the rings to me here in the USA. But it worked until I sold it. That same customer brought me equipment for another 2 years before I moved away, and he never said anything about it going bad.

 

[patrickw7843]

I've done a rebuild on one like that once. Replaced the rings. Thanks to @bertsmobile1 , who turned me onto Aliaba (one what ever the name of that company was) It was pretty easy. It took them forever to send the rings to me here in the USA. But it worked until I sold it. That same customer brought me equipment for another 2 years before I moved away, and he never said anything about it going bad.

I may do that. I have it torn apart, bow. It may be a spare parts pile, too.

 

[PTmowerMech]

I may do that. I have it torn apart, bow. It may be a spare parts pile, too.

Those spare part piles tend to get a little high. Then about the time you take them to the scrap yard, suddenly you need something out of it. lol

 

[patrickw7843]

Yeah, exactly