Carb leak

[Backstage]

Trying to get a carb working here.

Walbro WTEA-1 for a 455 husky. Been working on this saw for a while, hopefully we’re in the home stretch.
This is a Walbro carb, not a copycrap.

Symptoms before were unresponsiveness to L jet and low idle adjustment, rough idle and dying after WOT, lack of power at WOT, died when I sprayed carb cleaner on the intake side of the carb, though it could have been going through any number of places. Did not hold pressure or vacuum on either intake or purge intakes.

I pulled the carb and put Walbro rebuild kit in. Looked clean and no varnish or gunk. Pump side seals/gasket, diaphram and gasket, needle valve/lever, filter screen. Gently lapped the needle seat with the sharp and square ends of one of those bamboo skewers (great multipurpose tool to have around btw).

Reassembled and still has no seal. Pressure and vacuum fail to hold. Pressure from either nipple will vent out the jet inside the carb body. I can see fuel coming out when I prefill it and bubbles when immersed.

Back on the saw, the saw just floods and refuses to pop, even with muffler removed.

I’m hoping to sell this saw and not loose any sleep over someone having a bad experience, but I’m already approaching the point where I would have been better off burning it in a fire, not even counting the time I put into it. I have to count that as positive experience. So I’d rather not just throw $90+ more at it and replace the carb completely if possible. The aftermarket $20 WTA-29 carbs are a mediocore fit at best.

Any pointers here would be helpful.

 

[Backstage]

Also should note that both h and L screws are set for 1-1/4 and we have great spark (nothing changed on spark since before the carb work)

 

[Chevboy0167]

. Did not hold pressure or vacuum on either intake or purge intakes.

Are saying you pressure tested the crankcase and it did not hold pressure???

 

[Woodslasher]

Trying to get a carb working here.

Walbro WTEA-1 for a 455 husky. Been working on this saw for a while, hopefully we’re in the home stretch.
This is a Walbro carb, not a copycrap.

Symptoms before were unresponsiveness to L jet and low idle adjustment, rough idle and dying after WOT, lack of power at WOT, died when I sprayed carb cleaner on the intake side of the carb, though it could have been going through any number of places. Did not hold pressure or vacuum on either intake or purge intakes.

I pulled the carb and put Walbro rebuild kit in. Looked clean and no varnish or gunk. Pump side seals/gasket, diaphram and gasket, needle valve/lever, filter screen. Gently lapped the needle seat with the sharp and square ends of one of those bamboo skewers (great multipurpose tool to have around btw).

Reassembled and still has no seal. Pressure and vacuum fail to hold. Pressure from either nipple will vent out the jet inside the carb body. I can see fuel coming out when I prefill it and bubbles when immersed.

Back on the saw, the saw just floods and refuses to pop, even with muffler removed.

I’m hoping to sell this saw and not loose any sleep over someone having a bad experience, but I’m already approaching the point where I would have been better off burning it in a fire, not even counting the time I put into it. I have to count that as positive experience. So I’d rather not just throw $90+ more at it and replace the carb completely if possible. The aftermarket $20 WTA-29 carbs are a mediocore fit at best.

Any pointers here would be helpful.

Sounds like the check valve is bad, the p/n for one is 502846801, Jack's small engines has one for $11.

 

[Backstage]

Are saying you pressure tested the crankcase and it did not hold pressure???

Not talking about the crankcase, though that’s been tested and passed with rock steady colors. It holds pressure like it was made in a JPL lab.

 

[Chevboy0167]

Whew... ok. How about pressure test the fuel line and filter? Fuel tank vent letting air in when it should?

 

[Backstage]

Sounds like the check valve is bad, the p/n for one is 502846801, Jack's small engines has one for $11.

That could make sense. It looks like the carb is just letting ALL the fuel through with little to no restriction any time air passes over the nozzle.

Looks like you’re referencing the Nozzle Assembly, which includes the check valve? So blowing air through the main carb channel must have been what caused that. I didn’t blow down the metering hole or anything.

For the life of me I can’t see how that thing is removable. It’s press fit in and no easy access from the main channel.

 

[Backstage]

Whew... ok. How about pressure test the fuel line and filter? Fuel tank vent letting air in when it should?

We have good fuel flow…too good appears to be the problem. All new fuel lines, filter, impulse line, good seals to all points there.

 

[Backstage]

Just tested also with the ACTUAL impulse line. There’s no impulse nipple on this carb, it’s on the boot and you have to either use the boot attached or work with the little innocent looking hole on the boot face. Tested both ways, holds pressure and vacuum. So we have a good needle valve/seat, and the saw can tell the carb properly when it wants gas.

 

[Chevboy0167]

WOW.... I totally read the 1st post all wrong! LOL Don't mind me... too much holiday confusion set in......

 

[Woodslasher]

That could make sense. It looks like the carb is just letting ALL the fuel through with little to no restriction any time air passes over the nozzle.

Looks like you’re referencing the Nozzle Assembly, which includes the check valve? So blowing air through the main carb channel must have been what caused that. I didn’t blow down the metering hole or anything.

For the life of me I can’t see how that thing is removable. It’s press fit in and no easy access from the main channel.

Yep, that's what I'm referencing and yes it has the valve piece in it. It is a press fit, and I believe you just press the old one through into the main hole through the carb.

 

[Backstage]

WOW.... I totally read the 1st post all wrong! LOL Don't mind me... too much holiday confusion set in......

Get you some egg nog. The fun stuff!

 

[Backstage]

Yep, that's what I'm referencing and yes it has the valve piece in it. It is a press fit, and I believe you just press the old one through into the main hole through the carb.

Oh! Yep, it comes through with an arbor press and a short piece of hardwood dowel. Tested on my WTA-29 (piece of crap) that’s been used as a side-side comparison. It did get pretty mashed coming through, so I’m going to have to be ultra cautious removing the OEM nozzle. Probably turn a stepped piece on the lathe to ensure it doesn’t overtravel and mash it into the flow channel bottom.

Thanks! I’m getting that part on order.

 

[cscltd]

If carb won’t hold pressure, it’s the inlet needle/seat, pump side issue, or impulse area on carb.
nozzle will only hold minute pressure otherwise fuel won’t go through, they will show a leak if pressurized fuel gettting past needle
put carb in cup of water while pressure testing and see were air bubbles are coming from. If from metering side, take cover and metering gasket off and retest to see if bubbles coming from inlet needle.

 

[Backstage]

It’s not the inlet needle. We‘ve covered that very well in this thread, unfortunately.

Just did a clean job of removing the check valve. Applying my mityvac tester to the bottom, it holds pressure and allows vacuum. That’s not what I was expecting if this part was damaged. :/

 

[cscltd]

Funny, first post says, 5th paragraph says, pressure and vacuum fail to hold?
did I miss something that now it holds pressure?

 

[Backstage]

Ninth post

 

[cscltd]

I guess u got it under control very well fortunately- I will tap out then.

 

[Backstage]

Well sort of... We’re thinking it’s the check valve nozzle assembly. But after removing it, it passes flow checks with flying colors.

At this point I’m saying “screwit”. Ordered a carb assembly. It doesn’t make sense buy the $10 +shipping part for a 50% chance of success, assuming replacing that doesn’t cause additional leak issues.

If that doesn’t work, my next step is to (as first quoth by the venerable Ellen Ripley) “…take off and nuke the entire site from orbit. It’s the only way to be sure.”

 

[Old2stroke]

Just tested also with the ACTUAL impulse line. There’s no impulse nipple on this carb, it’s on the boot and you have to either use the boot attached or work with the little innocent looking hole on the boot face. Tested both ways, holds pressure and vacuum. So we have a good needle valve/seat, and the saw can tell the carb properly when it wants gas.

So we are confused. Does this carb get the impulse signal from a separate line directly from the crankcase or does it get it from a hole in the flange where the carb mounts to the engine. If you are actually testing an impulse port on the carb, it just operates the pump chamber diaphragm and should hold both vacuum and pressure, has nothing to do with the fuel inlet from the tank and cannot be used to test the fuel inlet valve in the carb, this valve has to be tested by applying pressure to the fuel inlet port and applying vacuum to it is a meaningless test. The nozzle check valve should be easy to blow through going from the fuel chamber into the carb throat and should hold vacuum going in the other direction. These devices have a little rubbery disc that is often distorted and becomes intermittent so "bench testing" it doesn't mean it will continue to work in a running saw.