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

#1

Evpena87

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


#2

B

bertsmobile1

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


#3

Evpena87

Evpena87

bertsmobile1 said:
not till we know the make & model number of the blower
Click to expand...
Craftsman backpack leaf blower 32cc ohv 4 cycle
model 316.79401


#4

dougand3

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?


#5

Evpena87

Evpena87

dougand3 said:
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?
Click to expand...

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.


#6

dougand3

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?


#7

dougand3

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.


#8

Evpena87

Evpena87

dougand3 said:
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.
Click to expand...
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?


#9

dougand3

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.


#10

Evpena87

Evpena87

dougand3 said:
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.
Click to expand...

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.


#11

B

bertsmobile1

Slide the carb off , turn it sideways and blow air through it
You should get a stream of fuel coming out of it
This stream should respond to the throttle position
If you have used carb cleaner on the internals of the carb, you may have killed it.
Most of the check valves will not take carb cleaner which is why Walbro has come up with a new ( and very expensive ) formula that will not damage either the check valves nor the the needle valve tip.


#12

Evpena87

Evpena87

I haven’t
bertsmobile1 said:
Slide the carb off , turn it sideways and blow air through it
You should get a stream of fuel coming out of it
This stream should respond to the throttle position
If you have used carb cleaner on the internals of the carb, you may have killed it.
Most of the check valves will not take carb cleaner which is why Walbro has come up with a new ( and very expensive ) formula that will not damage either the check valves nor the the needle valve tip.
Click to expand...
i haven’t used carb cleaner on the internals of this carb. Only sprayed into intake.


#13

B

bertsmobile1

Good, so we can scratch that one off the list
How did you go with the air through the carb ?


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