# Blower dies when hot



## InstantLegend (Jun 5, 2005)

I have a 3-4 year old Echo PB-403T backpack blower that looses power after 5 minutes, once it warms up. I initially thought it was running out of gas so I filled it up. Now I am not sure if it was actually out. The same thing happened right after filling it up. It always starts easy. If I hold the throttle open it dies. If I release the throttle, it idles ok. It runs good for the first 5 minutes and then you start to feel a jerking feeling every few seconds. It's kind of like it is missing, but I can't hear the miss. I only feel the blower jerk on my back. Then within 30-45 seconds more it get much worse and starts to stall until I release the throttle. 

I checked the air filter. It was very clean.
I replaced the plug and tried it again. The same thing happened.
I checked the spark arrestor screen in muffler. It was very clean.
I removed the muffler and checked the exaust port for carbon build up. It was clean.
I checked the gas lines and fuel filter and they looked fine.
I dumped out the gas/mix and replaced it with a fresh mix. Gas is mixed 50:1 as recommended with a quality Stihl 2 cycle oil. Same problem.
I removed the carb and completely disasembled it and cleaned it. I really didn't find any dirt in it. Same problem still.
I also did a compression test. It ready 135 psi.

What else could it be? The ignition module? Is there any way to test this?


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## 30yearTech (Sep 14, 2006)

It really sounds like a fuel issue. You may want to replace the fuel filter, you can't always tell by looking at the filter if it's good or not. I really think the problem lies with the high speed check valve in your carburetor, based upon your description, I think the engine is running too lean at high speed. There may also be something plugging up the nozzle. When you cleaned your carburetor, did you remove the throttle valve and flush out the nozzle and main jet??


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## InstantLegend (Jun 5, 2005)

If it was the fuel filter, why would it run ok until it warms up?

I did remove the main jet and sprayed carb cleaner in there and all the other small holes. What is the throttle valve? I am not sure if I removed that or not.


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## InstantLegend (Jun 5, 2005)

I just looked at a parts diagram. I didn't remove the throttle valve.

Do you think I should get a carb kit for it?


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## 30yearTech (Sep 14, 2006)

It may have nothing to do with the engine warming up, it may run until most of the fuel from the hose is used up and the restriction from the filter slows the flow enough to cause an issue. 

Never mind about the throttle valve, I was thinking your blower used a rotary valve carburetor, but it does not, so that would not be the problem. The high speed check valve could still be the problem though.


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## InstantLegend (Jun 5, 2005)

Can anyone tell me if this blower (Echo PB-403T) has a catalytic converter?


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## geogrubb (Jul 28, 2006)

It could be the gas cap is not venting properly, try running it with the cap loose and see what happens. Have a good one. Geo


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## InstantLegend (Jun 5, 2005)

Thanks for the suggestions. I'll try them.

This carb has a second smaller line from the the gas tank to the carb. Is this some kind of overflow return or what? It goes into the top of the tank and ends there. Is it for venting?


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## 30yearTech (Sep 14, 2006)

InstantLegend said:


> This carb has a second smaller line from the the gas tank to the carb. Is this some kind of overflow return or what? It goes into the top of the tank and ends there. Is it for venting?


It's the return hose for the carburetor purge pump. The little bulb on the carburetor that you push to circulate fuel from the tank to the carburetor and back to the fuel tank.

Your model also shows to use a spark arrestor muffler w/catalyst.


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## InstantLegend (Jun 5, 2005)

I tried running it with the gas cap open and it didn't work any better.

I replaced the fuel filter and still not improvement.

I saw the owners manual said to have the exaust port cleaned / decarboned every 3 months or 90 hours so I checked that. It was so clean there was nothing to clean out. Obviously there was no improvement from this.

I finally got a carb kit and rebuild the carburetor and now it is running good again.

Thank you to all for your suggestions and help.


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## 30yearTech (Sep 14, 2006)

Glad you got it figured out, thanks for the update!!


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## Rayg (Feb 14, 2021)

I have the same problem
Echo PB650
Starts runs like a champ for 10 min then starts running up then down until eventually it dies. I've tried everything carb,lines,filter,gas,new coil,running with cap off . Once it starts running erratically at high I can turn down the throttle and it will run roughly like at a high idle.. any suggestions
Thanks


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## Milton Fox Racing (May 27, 2014)

Did you order a carb kit or new carb!


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## Rayg (Feb 14, 2021)

Milton Fox Racing said:


> Did you order a carb kit or new carb!


New carb


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## Rayg (Feb 14, 2021)

Rayg said:


> New carb


New coil


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