32cc ohh leaf blower won’t turn on after new carb

[Evpena87]

I have a 32cc leaf blower that I replaced the short block on. I finally got it together but it wouldn’t start. I sprayed carb cleaner into the carb and it turned on right away. It ran for 5 seconds to reach full throttle then shuts off. I did not touch the throttle in this process. I replaced the carb thinking it may not be getting fuel but it is acting exactly the same way.
Any idea that I can try to fix this issue?

thanks

 

[bertsmobile1]

not till we know the make & model number of the blower

 

[Evpena87]

not till we know the make & model number of the blower

Craftsman backpack leaf blower 32cc ohv 4 cycle
model 316.79401

 

[dougand3]

MTD tiny 4 cycle. Troy Bilt has them and they are known to have valve problems that you can't fix - I guess the reason for buying a short block.
Try throttle up while the carb cleaner charge is burning. You do have good fuel lines? You do purge air and see fuel moving back to tank?

 

[Evpena87]

MTD tiny 4 cycle. Troy Bilt has them and they are known to have valve problems that you can't fix - I guess the reason for buying a short block.
Try throttle up while the carb cleaner charge is burning. You do have good fuel lines? You do purge air and see fuel moving back to tank?

yea I cracked the original engine. This new engine had to have the valves adjusted right away. It’s got the new carb and new fuel lines with air purged out. I’m stumped because if I thought it was spark, it would come on at all.

 

[dougand3]

Well, if it runs normally for a short while on a fuel charge...you have compression and proper spark timing. Fuel delivery problem seems most likely. Maybe bad new carb?

 

[dougand3]

Just looked at that carb...make sure the impulse hole at 10 o'c is not blocked by the gasket. Gotta have push/pull on the fuel pump diaphragm.

 

[Evpena87]

Just looked at that carb...make sure the impulse hole at 10 o'c is not blocked by the gasket. Gotta have push/pull on the fuel pump diaphragm.

I made sure with the new gasket that the impulse hole was not covered. No luck though.
As I’m no expert with small engine carbs or carbs for any matter. Is the fuel supposed to come through the impulse hole when it is being primed?

 

[dougand3]

No, impulse is air/maybe a little fuel to make fuel pump diaphragm vibrate - that pulls fuel from tank thru the line with the fuel pickup. Impulse comes from piston going up & down.
I've only had 1 of these tiny 4 strokes that I fixed (sheared FW key), so I'm no expert. But I was not impressed - they basically complicate a 2 cycle with valves.
I ask again - does it run normally for 2-3 secs with fuel in carb throat or plug hole?
And you are sure fuel lines are hooked up correctly? To be safe - stick BOTH under the fuel level. If the purge line in the top of the tank (in air) is hooked to the FUEL IN port on carb - it ain't never gonna get any fuel. Normally, PURGE OUT is closer to the purge bulb.

 

[Evpena87]

No, impulse is air/maybe a little fuel to make fuel pump diaphragm vibrate - that pulls fuel from tank thru the line with the fuel pickup. Impulse comes from piston going up & down.
I've only had 1 of these tiny 4 strokes that I fixed (sheared FW key), so I'm no expert. But I was not impressed - they basically complicate a 2 cycle with valves.
I ask again - does it run normally for 2-3 secs with fuel in carb throat or plug hole?
And you are sure fuel lines are hooked up correctly? To be safe - stick BOTH under the fuel level. If the purge line in the top of the tank (in air) is hooked to the FUEL IN port on carb - it ain't never gonna get any fuel. Normally, PURGE OUT is closer to the purge bulb.

finally got to work on the blower again. I put fuel in the carb throat and it ran for 2 seconds. This is a “new carb”. Thinking it may be bad.