Echo SRM 225 starting problem/ fuel leak?

[Doug41]

Im new to this forum and DIY repairs. My echo srm225 has run great for years. Finally put in a new carb a couple yrs ago and all well until recently. Now very hard starting and fuel leaking out spark arrestor. The arrestor is very clean? Any ideas? “Another” carb. Any help appreciated.

 

[Rivets]

If you didn’t use an OEM carb, but purchased one off the web, than could be the problem. Before replacing try this. When you see the leak, set the unit down on concrete and loosen the gas cap. If it stops leaking, I’m guessing your tank vent is plugged.

 

[MParr]

Replacing a carburetor is not always the best route.
My old SRM225 was leaking fuel. I couldn’t see where it was coming from.
I replaced the primer bulb, the fuel lines, fuel filter, fuel tank grommet, and gaskets on both sides of the intake manifold block.
This fixed the leaking and I kept the original carburetor. The thing runs like new.

 

[StarTech]

Really need understand one thing here, The brush-cutter's tanks are only vented to break the vacuum not pressure. If the carburetor is leaking then it is usually one of two things. Either the metering diaphragm has stiffen to the point where it is holding the metering needle valve open or the metering valve or its seat is leaking. I have seen even OEM metering gaskets to go bad within a year because of all the fuel additives that is in our fuels. Doesn't matter if ethanol or non ethanol they are still there.

I even seen a couple times where OEM metering diaphragms failed within a month.

But as noted even the remote primers can cause problems but the SRM-225 use the Zama RB-K93 rotary barrel carburetor that has the primer on it and not remote.

Only one other would cause the engine to be flooded and that is lost of compression where fuel never ignites because the compression below 100 psi.

 

[Tiger Small Engine]

Really need understand one thing here, The brush-cutter's tanks are only vented to break the vacuum not pressure. If the carburetor is leaking then it is usually one of two things. Either the metering diaphragm has stiffen to the point where it is holding the metering needle valve open or the metering valve or its seat is leaking. I have seen even OEM metering gaskets to go bad within a year because of all the fuel additives that is in our fuels. Doesn't matter if ethanol or non ethanol they are still there.

I even seen a couple times where OEM metering diaphragms failed within a month.

But as noted even the remote primers can cause problems but the SRM-225 use the Zama RB-K93 rotary barrel carburetor that has the primer on it and not remote.

Only one other would cause the engine to be flooded and that is lost of compression where fuel never ignites because the compression below 100 psi.

Blow with a compressor air gun all around carburetor and fuel lies. Remove air cleaner and start trimmer and check for fuel leaks.

 

[StarTech]

Tiger you really should invest in a new thinking cap as the old one appears to be defective.

The OP said fuel coming out the exhaust, leaking around the carb or fuel lines will not fill the crankcase. Only a carb that is leaking into its throat or lack compression causes this. And sheared flywheel key could shift the ignition timing but that is pretty rare.

And with crankcase flooded with fuel it going to be near impossible to start the engine.

 

[Hammermechanicman]

I would pull the muffler and check piston and cylinder. Check the cylinder and crankcase bolts are tight. Loose crankcase bolts common on Echo trimmers. Check for good spark and replace plug. If still floods and hard to start then carb prob. If non OEM on it now don't bother working on it just fleabay another one.

 

[StarTech]

Strange of all the Echos I have worked on I haven't seen any loose crankcase bolts and I would thought that would have shown up on the ones that were commercially used.

 

[Hammermechanicman]

I have seen about a half dozen with loose crankcase bolts that causes loss of primary compression. Mech at an echo dealrt said he sees it a lot on the homeowner grade stuff.

 

[StarTech]

I can see where it would cause lost crankcase vacuum. Not much pressure in the crankcase as the piston is moving sucking in fuel/air mix.
I keep an eye out for them then. My biggest problem with homeowners is the straight gassing other carb problems.