Nothing but flooding (Husqvarna 44)

[Ibeatgodzilla]

Hi all,

I'm normally pretty good with repairs, finding problems etc - but you never finish learning, and I am having trouble with an old Husvarna 44 at the moment.

Initially, the problem was no spark. The coils for these costing as much as the machines themselves are worth, I did a bit of research and found out that with a little filing, a 51/55 coil could be mounted.So I did buy and a fit a new one of them, and have got a good spark now.

However it still won't run. So, naturally, dismantle and clean out the carb, rebuild with full rebuilt kit. No difference whatsoever (!).

The cylinder floods with petrol like there's no tomorrow. I can put the mixture screws all the way in to the stops, pull the cord a few times, and it'll fire, rev for a second, then before I have a chance to react, die out again. Obvious thing to do; unscrew the screws a bit. Nope, won't start at all. Going by the spark plug the thing is just soaked in fuel. Every time I look at it to check, it's wet.

Definitely no air leak problem then, that's one good thing I guess.

Only thoughts are; either the valve inside the carb is staying open/not closing properly causing fuel to be delivered in permanence - however upon further disassembly of the carb I notice that the little aluminium 'dot' on the membrane that pushed on the valve lever is deeper on the aftermarket new membrane than the original. However swapping out to the original again yields no change, same issue. It does appear to be closing. I have tried carefully bending this lever to make it 'more closed' but again, no difference whatsoever when trying to start it.

Or, other possibility, I'm getting spark when testing the plug outside of the cylinder, touching against it, but not sparking properly when back inside the cylinder; or timing is wrong and it's sparking, but not when it should, so flooding - however timing is fixed by the flywheel, which I haven't removed. I saw on more than one post that a 51/55 coil with filed mounting holes fits - and works - in a 44; so in theory, why would this be the issue? And doesn't seem to answer the symptoms of it only firing briefly when mixture screws are in to the stops before flooding again.

I'm a bit stumped so if anybody has any ideas, thoughts, things for me to investigate I'm all ears. The coil wasn't exactly a great expense, but it more than anything it seems a shame to consider the saw scrap if it can be made running again - it seems so close.

Thanks in advance!

 

[Pioneer]

You already corrected the main problem of the improper diaphragm dot depth, that one tripped me up too, I learned you can take nothing for granted in a carb kit to be the same as original. Swapping in a known good carb would be the best choice, but not everyone has that option. Pressure test it? Make sure the diaphragm and gasket are stacked in the right order?
I usually eliminate the simplest or most obvious solutions first, then work my way into the more complicated ones.
Hopefully someone will chime in with other solutions to the same type of problem without you having to waste hours chasing it down.

 

[barie]

Try to file the "aluminium dot" to a level where the lever closes all the way

 

[Old2stroke]

You have to pressure test the carb to be sure the inlet valve is seating and being held closed, if it passes, then test for a badly leaking welch plug that is allowing fuel to bypass the metering screws. Another rare possibility might be a leak between the fuel tank and the crankcase cavity if it is a pro design engine (not a clamshell), a pressure/vacuum test of the engine should verify this.

 

[Huskvarna hotellgäst]

Another rare possibility might be a leak between the fuel tank and the crankcase cavity if it is a pro design engine (not a clamshell), a pressure/vacuum test of the engine should verify this.

Extremely rare on a 44, the c/case and fuel tank not being integrated

 

[Huskitoter]

You can double check the low mixture screw to eliminate that. It's easy to come out on the losing end of that 50/50 if you take them out when cleaning the carb. Check here to see the tips .... https://www.partstree.com/models/44-husqvarna-chainsaw-1985-05/carburetor-parts-2/

 

[vhmtach38]

Make sure the needle metering lever is at the correct height.

 

[EchoRomeoCharlie]

Pressure test the carb on the fuel line barb, odds are the metering needle isn't closing and holding pressure so there's no metering of fuel and it floods very quickly.

Had this a few times. The last few times was actually a weak spring. The lever was set correctly, however, the spring wasn't re-seating the needle OR it couldn't hold it down with enough pressure to shut of the flow of fuel. On old carbs, the springs can be worn. So far I've been able to stretch them out a bit, and they seem to run good.

 

[auskip07]

im dealing with this on my 51/55 build. I put it up because i just cant get the carb right and initially i just replaced the gaskets and diaphram but after tinkering with it tonight i broke down and bought a replacement carb.