carb leaking on 545

[1d10t]

Hello

 

Posted elsewhere, but posting here as well. Still figuring out different stuff that's wrong with my 545.

Recently the purge bulb completely stopped working. 

I removed the carb and tried to vacuum test the purge nozzle like this:

https://imgur.com/a/m8VWT7f

 

it was not holding vacuum at all.

This is the video from autumn, was also leaking but not as bad:

https://imgur.com/a/CSziAIF

 

I bought the oem carb rebuild kit, replaced all 3 gaskets (top and bottom side, autotune unit gasket), 

both diaphragms, needle, needle lever and screen.

It is better now but still leaking fast (worse than the second video, loses all vacuum in about 2 seconds).

It seems to be sucking air through main nozzle:

https://imgur.com/a/w42csDl
 

Any ideas what exactly could be leaking? I found some info about an oring on the accelrator pump going bad, but 545 seems

to not have accelrator pump at all. 

Pressure test is fine, no leakage at all (and wasn't any before carb rebuild).

[Muddy42]

Sorry its a bit hard to tell from the video which line you are applying pressure/vacuum to?

 

Personally I test the fuel inlet, the purpose being to test the needle seats properly and then pops off with a certain amount of pressure.

 

Ive never had reason to test the purge line, but I think all that would tell you is whether the check valve in the fuel pump diaphragm is working.  Even then I think the carb would work.

 

Just be careful, some of your testing looks pretty forceful and that may have caused further damage.

[1d10t]

it is less than 0.5 bar of vacuum. I just tested a different (older carb) with a purge bulb and it holds vacuum perfectly if I squeeze the intake fuel line.
Also since it seems to be worse than it was, even with the rebuild, it certainly seems something is wrong, I just don't know what else I can replace, there is nothing I can see in the diagram that could be leaking and I can fix without replacing the whole carb.

[adw]

That is the purge connection so it’s going to hold a vacuum , the purge bulb pulls fuel from here, into the bulb and pushes back to tank, the carb has a compensator not an accelerator pump.

 

 

[adw]

Sorry NOT going to hold vacuum.

[adw]

As I made complete dogs dinner of this I will explain a bit better,

if you have a remote purge bulb it will have two connections on the back, a long connection which is the pressure side, and a short connection which is the suction side, so when the bulb is depressed a pressure is caused, as the bulb re inflates it creates a suction, there will also be a non return valve in the bulb so as to stop pressure down the suction side, there may also be a non return valve in the carb, so the short suction connector goes to the carb, this will be the connection closest to the metering side of the carb, this will draw fuel from the metering chamber into the bulb, when the bulb is depressed the fuel in the bulb is sent back to the fuel tank.

so back to the original question why does it not purge,

fuel filter in the tank blocked

fuel screen in the carb blocked

fuel hose kinked or split

purge bulb faulty, non return valve stuck, or pin hole in bulb

pipes incorrectly connected

inlet needle stuck

non return valve in main jet faulty

metering diaphragm split.

[1d10t]

so the only possible culprints could (probably) be

 

inlet needle stuck (replaced that one today)

non return valve in main jet faulty

Since everything else is new (at most 3 months old and i doubt it would have the same problem as the old parts immediately).

 

When it happened before and purge bulb would not pull fuel, I could fix it by hooking up a vac tester directly to purge valve and making some vacuum. Once fuel got through, it would work for a while. 
Is it possible to check the non return valve in the main jet? Or would my only option be replacing the carb?
As for inlet needle, is that the one that's attached to the spring and was part of the carb kit? Since I did replace that one today, along with everything in the kit (3 gaskets, 2 diaphragms, needle, spring and screen).

[adw]

If you do a vac test on the purge connector and fuel is down out then is it not just an issue with the bulb itself??

[1d10t]

I guess I wasn't clear, there is no fuel coming out, it's just that it wasn't pulling any fuel to the purge bulb. That's happened before. I did a vac test on the purge valve on the carb since I assumed that it has to hold vacuum (another carb from solo 639 that I have DOES hold it). But if as you say it shouldn't, then I guess this is fine? I'll reassemble everything and see if purge bulb works now.

[adw]

Take the purge bulb out, depress it, whilst depressed stick your thumb on the short connector, let the purge go, it should not re inflate.