Echo PB-500T won’t start properly

[Cfs]

I have a PB-500T. Serial P31212136027
I can get it to start if I pour a small quantity of gas into the carb. After it starts it runs great full throttle and low idle. If I do not pour gas into the carb I can prime the carb ( a dozen pumps or more..full choke and pull, pull and pull some more and it never even pops. I gave pulled the spark plug after and it seems dry. What am I missing? This is a Walbro WAL-1 carb. It has the odd horizontal air valve on top of the carb. I have very little experience with this style of carb.

I have spark and I have 115 lbs of compression and it runs great once it starts. It seems like the gas isn’t getting into the cylinder. I replaced the fuel line and fuel filter, I replaced the coil and this problem is with a new aftermarket carb which did not correct the same issue as the original Echo/Walbro carb.

Could I gave an aid leak somewhere?
Any ideas greatly appreciated
CFS

 

[StarTech]

I have a PB-500T. Serial P31212136027

This is a Walbro WAL-1 carb. It has the odd horizontal air valve on top of the carb. I have very little experience with this style of carb.

It is what is called a choke. It is used to start the engine when it is cold. Close it and try starting the engine.

Now the little lever which is red or orange does tend to get broken off.

 

[Cfs]

It has a choke lever on the air filter box. The part on top of the carb echo calls an air valve assembly and it opens and closes via a link based on the throttle position and it fits into another part called a valve assembly. This 2nd valve asby is attached to the cylinder and 2 air hoses run from it to 2 parts identified as reed plates… inner and outer. I assume that the gas mixed with air is pulled through the carb and the valve assemblies through the reed plates and into the cylinder. I would was able to download an IPL of my model and have access to part numbers etc. however I am lacking the experience to trouble shoot the problem and I do not want to just throw parts at it. I can try to start it without choking it and see if that does anything. But as I detailed earlier the plug is not wet after failing to start with the choke on. I do not see the problem as too much fuel, more too little or no fuel. I am wondering if the reed asbys are gummed up and not openining like they should or if an air leak on the cylinder or crankshaft seals are reducing the pressure that needs to be exerted onto the reeds gat is needed to draw fuel into the cylinder. Especially when cranking by hand, maybe once it is firings and thus running at operating speed/rpm’s, and that higher pressure opens the reeds and it can continue to run
Hopefully someone has had a similar problem
CFS

 

[Cfs]

It has a choke lever on the air filter box. The part on top of the carb echo calls an air valve assembly and it opens and closes via a link based on the throttle position and it fits into another part called a valve assembly. This 2nd valve asby is attached to the cylinder and 2 air hoses run from it to 2 parts identified as reed plates… inner and outer. I assume that the gas mixed with air is pulled through the carb and the valve assemblies through the reed plates and into the cylinder. I would was able to download an IPL of my model and have access to part numbers etc. however I am lacking the experience to trouble shoot the problem and I do not want to just throw parts at it. I can try to start it without choking it and see if that does anything. But as I detailed earlier the plug is not wet after failing to start with the choke on. I do not see the problem as too much fuel, more too little or no fuel. I am wondering if the reed asbys are gummed up and not openining like they should or if an air leak on the cylinder or crankshaft seals are reducing the pressure that needs to be exerted onto the reeds gat is needed to draw fuel into the cylinder. Especially when cranking by hand, maybe once it is firings and thus running at operating speed/rpm’s, and that higher pressure opens the reeds and it can continue to run
Hopefully someone has had a similar problem
CFS

So I went to a local small engine shop who has a tech who really knows Echo. I was not able to speak directly to him since he was at lunch. The owner shuttled back and forth from the lunch table to the front counter and asked him about my problem. I brought my tablet with a pdf of the IPL for my model. They told me that the parts called reeds are really not reeds they are just hollow fittings that the fuel air mix can get to the cylinder through. They told me not to put the throttle on full, just take it off of the kill position, choke it via the small orange lever and pull the starter rope. They told me that setting it to high speed would prevent it from starting. So when I got home I did exactly what they told me and it would not start, in fact it never even popped. So I pulled the spark plug added about a tablespoon of gas ,replaced the plug choked it and it started on the 2nd or -3rd pull and it ran great. I shut it off and it restarted after 20-30 seconds. It would not start 5 mins later.

I think the tech refered to this Walbro YAL-1 carb as a dual barrel. There is a round opening with a brass throttle butterfly at the bottom of the carb and the valve above it has a horizontal l barrel that has a slot cut in it that as you engage the throttle more of the opening is opened for air to flow through.

It really seems like it is not getting enough gas to start. Either that or an air leak. it does have good Compression. Anybody have a similar issue that they found a fix for? Any and all ideas welcome

CFS

 

[StarTech]

Okay having to do some research in this end. Not able to find a Service manual via the net so I got try another source here but that takes several days and can come back nothing in the library.

Walbro WLA-1 Carb.

The reed valve assemblies are actual reed valves. Here is an image of one. Someone doesn't know what they are talking about.

The Walbro WLA-1 carburetor is a scavenger style carb. It is a design I haven't seen here as most of the ones I see here are the Zama versions which rotary barrel style. It allows additional air into the cylinder assy at mid and full position as to lean out the fuel mixture and to allow fresh air to replace the exhaust gases.

Check the intake gasket to make sure you didn't damage it, Check the cylinder to lower crankcase screws are good and tight. Another that can be checked without is seal off the intake and the two reed valve assemblies and do a pressure/vac test of the crankcase which checks for leaky oil seals the cylinder to crankcase gasket. IF the oil seals are leaking on vacuum or pressure they can cause lack fuel getting to the upper cylinder. It doesn't take much at times to cause problems. Btw lower crankcase air leaks does not affect the compression.

Crankcase screws are torque to 65-95 in lbs per the service data file. I usually use the higher end number.

As for reed valves they seldom ever give problems.