# Echo PB-250 will not take throttle.



## Ryan_289 (Dec 24, 2019)

Went to start the blower and it will start with choke but I can never get it to take throttle or come off of choke. This happened all of the sudden. Started and worked perfectly one week and the next this? My wife or myself use this regularly so I dont think bad fuel is the problem. The fuel bulb was cracked and leaking so I replaced that but no change. Any suggestions? 

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## Manic84 (Dec 25, 2019)

If it won't run off of choke and bogs like that, it means the engine is starving for fuel, I'd look at the fuel filter and give it fresh fuel just to rule them out, but a carb kit is what you'll probably need.

If the bulb was that bad off and needed to be replaced, it's probably time for a new kit as well.

Echos usually have the zama RB series carbs. Look at the carb and check what variant of RB you have, it should be etched on the side, after you look go ahead and post what type you have.

Merry Christmas!


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## Okie294life (Dec 25, 2019)

Manic84 said:


> If it won't run off of choke and bogs like that, it means the engine is starving for fuel, I'd look at the fuel filter and give it fresh fuel just to rule them out, but a carb kit is what you'll probably need.
> 
> If the bulb was that bad off and needed to be replaced, it's probably time for a new kit as well.
> 
> ...



I had a very similar issue with mine (carb) come to find out these carbs aren’t rebuildable like the good ol’ days. Do yourself a favor and get a new carb, OEM....or not and scrap it. I found one one eBay for around 15$.


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## banditt007 (Jan 28, 2020)

Also check out anything related to fuel delivery, kinked fuel line, clogged up filter, pin hole in the fuel line sucking in air. As other posters stated, for sure starving for fuel. Probably looking at a new carb, but check the other things first.


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## Okie294life (Jan 31, 2020)

banditt007 said:


> Also check out anything related to fuel delivery, kinked fuel line, clogged up filter, pin hole in the fuel line sucking in air. As other posters stated, for sure starving for fuel. Probably looking at a new carb, but check the other things first.


Yes if you don’t find anything wrong with the fuel line or filter, and you do replace the carb, replace all that crap also anyway. My blower is about ten years old, once you got everything apart you might as well replace all of it to get another ten years out of it without replacing anything else. It’s just as easy to do all of it, and it doesn’t cost that much more.


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## Ryan_289 (Feb 4, 2020)

It was the carb. Something happened inside it and when you tried to open the throttle, the top lever did not raise up enough to clear the carb screws. The new on rises up as it opens and clears. Fired right up with a replacement carb.


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## Okie294life (Feb 4, 2020)

That’s what I thought, hope it runs another 10 years.


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## Conquistador3 (Feb 5, 2020)

Okie294life said:


> That’s what I thought, hope it runs another 10 years.



Echo and Shindaiwa use the same 21.2 and 25.4cc short blocks on a bunch of products, from trimmers to handheld leafblowers. They are pretty reliable little units... except the carburetors. I don't know what EPA-compliant units use, but the Euro-compliant ones we get here use Zama RB carburetors that will go five years at very most and seem pretty unresponsive to rebuilds. The membrane kit alone is €20 from Echo... it literally makes no sense fixing them. Aftermarket units are just cheaper all around and I haven't found a defective one yet. 

I have an SRM-222 which I am using as a testbed to see how long these units will go before they become uneconomical to rebuild. Carburetor was gone after four years and other non-engine parts have already started to fail: unless I find a seized unit to use as spare hulk on the cheap it will probably be uneconomical to fix in a couple of years.


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## Okie294life (Feb 5, 2020)

Conquistador3 said:


> Echo and Shindaiwa use the same 21.2 and 25.4cc short blocks on a bunch of products, from trimmers to handheld leafblowers. They are pretty reliable little units... except the carburetors. I don't know what EPA-compliant units use, but the Euro-compliant ones we get here use Zama RB carburetors that will go five years at very most and seem pretty unresponsive to rebuilds. The membrane kit alone is €20 from Echo... it literally makes no sense fixing them. Aftermarket units are just cheaper all around and I haven't found a defective one yet.
> 
> I have an SRM-222 which I am using as a testbed to see how long these units will go before they become uneconomical to rebuild. Carburetor was gone after four years and other non-engine parts have already started to fail: unless I find a seized unit to use as spare hulk on the cheap it will probably be uneconomical to fix in a couple of years.


They do and I couldn’t really find a way to rebuild the carb since they went to the the weird little rotary valve inside, they are damn near impossible to rebuild. My Tanaka trimmer has the same setup, but the walbro version.....not worth wasting time to rebuild.


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## Manic84 (Feb 6, 2020)

Most of the Echo machines I work on have the Zama RB series carburetors, I find myself looking at an absurd rate of failure with these carbs. The zama RB-188(needle included) kit, which works for most carbs in the RB series, comes out to about $10(USD) each. While the GND-106(gaskets and diaphragms only) works for some in the series and comes out to $8 each, some carbs respond to a simple rebuild, others do not.

People bring me these aftermarket carbs to put on their machines and they honestly have a 50/50 shot of working. People see the price of a OEM carb, get sticker shock, then see a aftermarket carburetor priced about the same as a kit, but don't want to bother getting a kit trying to rebuild it and still have it not work, so they get the carb.

That's fine, but these aftermarket carbs I've found either show-up DOA or have a limited life and then fail like the OEM carb would: Bogging, can't run off choke, excessive flooding or leaking fuel, sometimes you get a good one, it all works out and everyone's happy, other times... not so much.

While you can adjust both the OEM and aftermarket carburetors to try and make them run better, which can sometimes solve the problem, you have to constantly go back and forth on the needles as they're real touchy to adjustments, so little 1/8 turns is the way to go.

But if an RB series carb is on the way out, it becomes governed by what I like call "The Rule Of Four" where you can ONLY adjust the needles four times before you push it over the edge and you can't adjust it anymore and it fails completely. So you have to get good, like... OCD good at adjusting it.

Now as I said earlier, some respond to a rebuild and others do not, and it took me _*AGES * _to figure out the reason why these type of carbs fail so.

After ruling out an air leak of any kind and all other possible things under the sun, numerous RB carbs (killing a few) and descending into madness, in the end... I did not come out empty handed.

It all lies down to the main nozzle check valve, which thanks to design is just under the main jet, and is UN-serviceable. Because of the use of cheaper materials in the manufacturing process, this check valve is quite weak and prone to failure and thanks to ethanol laced gasoline, it's a death sentence for it. I've noticed for those that use the engineered premixed fuels, it does last a little longer but it's just a matter of time.

The classic symptom I've found is an overfilled purge bulb, I'll see it swollen with excess fuel and know that even if it runs now, it probably won't down the road. The check valve either gets gummed up or fails outright, sometimes a good soak in WD-40 overnight or cooking it in a ultrasonic cleaner for awhile might free it, but if it does you got lucky... and the clock starts again.

Because the valve has failed it'll leak fuel, flooding the engine royally, spilling out the muffler even while running, you'd think it's the needle or spring but no. As the engine runs and everything cycles though the carb and bulb, it'll suck in air unregulated pumping excess fuel to the metering chamber and will over-power the needle & spring or bypass it completely - flooding the engine, or if the valve is failing/gummed and not working properly, it'll bog, become unresponsive to rebuilds or adjustment, all because it's failed and there's nothing to regulate the fuel/air flow in the carburetor.

Here is a schematic of the Zama RB series to maybe help visualize what I've rambled about




The conclusion I've come up with is: you're either damned if you do and damned if you don't.
I try to get as much as I can out these carbs, because in the back of my mind, is the thought that every aftermarket carb I send out might come back later and some have.(maybe it's just luck?) And no one wants to pay (I don't blame them) for an OEM one,  just to have the same problem later. It's just not practical (economically) or even feasible in my location.(echo dealer service here is... difficult)


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## Conquistador3 (Feb 6, 2020)

I have learned a valuable lesson from my Stihl dealer: if a carburetor is still giving troubles after being cleaned and rebuilt, it goes straight into the scrap metal bucket unless it's NLA and there are no alternatives. Time is money, and I have wasted far too much time in my youth trying to resurrect those damn Walbro WT's. 

You folks in the US are lucky parts are so cheap and easily available. The first time I was doing one of these Zama RB's I discovered that due to some dodgy gentlemen's agreement only Echo and Shindaiwa dealerships carry rebuild kits, and as is their usual they will charge you an arm and a leg for the privilege. It will be €20 for the same kit that costs $10 in the US, thank you very much. 
But go on the Internet and you can get a whole Zama clone for under $15, shipping and taxes included. As crappy as the materials used are they cannot be worse than in the original. The older one I have installed is now over a year old: if it goes three/four years it's worth as much as the original for a fraction of the price.


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## Okie294life (Feb 6, 2020)

I must be lucky I found an OEM Zama for about 15$ shipped, it was ebay so no telling if it actually was but it had good reviews, and functions perfectly. I haven’t had a lot of luck with the aftermarket Chinese carbs. I tried one, and it ran but wouldn’t rev all the way up. I’ve had a couple for chainsaw carbs that were straight crap out of the box. I can rebuild a walbro WB or comparable zama in my sleep with both arms tied behind my back..never had any issues kitting those.


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