Echo 452VL fuel system help

[Dok]

I have a Echo 452VL that is giving me fits. I bought it at a garage sale. Even though it wouldn't start the piston/cylinder looked perfect and compression is almost 150lbs. It starts and runs fine when I dribble some gas in the carb then shuts down when that gas is gone. The problem is it isn't pumping gas to the carb, the fuel lines are dry as is the carb. Here is what I have done:

Rebuilt the carb, which is a Walbro. I don't have instructions for this carb so I put it together just like I took it apart. Could I have done something wrong in the rebuild to keep the carb from pumping gas? What should I look for?

Replaced the fuel line and filter. Tested the fuel line with a hand pump, fuel flows easily to the carb.

Checked the venting, which is through the cap. Cleaned the screen in the cap and it seems to vent freely. Tried starting the saw with the cap off and no difference.

Any help would be appreciated- I've exhausted my knowledge.
Thanks
Brad

 

[blis]

checked the impulse hose?

 

[Dok]

It doesn't have one. I'm not sure how the impulse works on this system?
Brad

 

[blis]

if it doesnt have impulse line it should have impulse channel in intake manifold, if not, then it wont work (becouse fuel pump works by vacuum/pressure cycle)...

 

[Fish]

When you were in the carb, did you remove the needle and blow out that
passage, and visually verify that it is clear?

 

[Dok]

Blis- check!, the manifold is ported. I removed the manifold and blew out the port with carb cleaner. I also shot some into port on the cylinder head, which looks like it turns down into the crankcase. Most of the cleaner seemed to shoot right back at me. Is there is check valve down there? Reassembled, dribbled gas in carb, started right up then shut down like before.
Brad

 

[Dok]

Fish- yes, I replaced the needle with a new one. The passage is completely clean and I replaced the screen at the opposite end of the passage with a new one. Question- is there a spec on the height of the tang that operates the needle valve (the part the diaphragm rides on?). I simply replaced the lever piece with the one that came in the kit. Thanks!
Brad

 

[Dok]

I googled an install page for the carb kit and set the height of the needle lever. It was off about 1mm. Unfortunately it still won't pump fuel. I'm going :crazy1:

 

[catskinr]

452VL manifold

I have one of these that I got for free. It was almost NOS, but like yours it wouldn't pump fuel. After two evenings in the shop, I discovered that the flanges on the plastic intake manifold had warped. Ten minutes with a piece of sandpaper on a piece of glass had that pesky problem fixed, and it now runs fine. It won't set any records, but it's reliable as a hammer.

 

[Sixxgun]

Echo 452vl

Who I must say this Thread has been informiative I have the same problems I thought it was the Spark but that was not the problem I'm going to have to check this out on my saw. Thank JASON

 

[Bob Wright]

Ditto on sanding the plastic heat block under the carb they do warp/shrink. Now it gets fuel to the carb under pressure with a tester but how about under suction using the carb.
I have said this before on the old orange 1970's Echo's the fuel line's become soft and suck shut and will not flow fuel so that may be your problem...Bob

 

[Sixxgun]

Echo 452vl

Well mine ain't the intake manifold I check for warpage and none. Iit's not getting any fuel to Carb and I tryed putting gas in the carb and still would not fire the Carb has been rebuilt and the electial is all good I just replaced all of that. Could it be the needle valves being into far or something with the carb?

 

[Bob Wright]

Sixxgun
Loosen the H-L carb screws up 4 complete turns from the bottom and see if it starts...Bob

 

[Sixxgun]

Echo 452vl

Well some new updates I had it start for 2 seconds (off of the gas in the carb) some how it flooded so I had to what until it was not . Could this be because of the h&L needles being to rich?