carb not getting fuel

[singinwoodwackr]

So, trying the other carb now...crossing fingers.
It is a different model than the other.

And...the mystery continues, sigh...

It is probably something stupid simple. Possibly the previous owner screwed something up that I'm just not seeing.

 

[Old2stroke]

So, trying the other carb now...crossing fingers.
It is a different model than the other.

And...the mystery continues, sigh...

It is probably something stupid simple. Possibly the previous owner screwed something up that I'm just not seeing.
View attachment 982682

If those studs are the same ones that mount the carb, there have to be nuts somewhere that clamp the carb to the intake block. Hope you aren't trying to start the saw with a loose carb?

 

[Brufab]

Thats crazy, sucks your still having troubles. it is something simple. Good luck! Keep us posted.

 

[singinwoodwackr]

If those studs are the same ones that mount the carb, there have to be nuts somewhere that clamp the carb to the intake block. Hope you aren't trying to start the saw with a loose carb?

Ha, no, wouldn't do that

 

[Smitty Smithsonite]

If the orientation of the gasket and diaphragm is wrong this could happen. Most of the time the gasket goes on first, but I vaguely recall some where this wasn't the case. If the diaphragm was installed first when it should be after (or on top of) the gasket, this wouldn't allow the needle to open far enough. In a vice-versa situation, it goes pig rich.

Another possibility is the needle is sticking, or the needle arm is bent too far upward away from the carb body.

 

[Okie]

Was the last carb you tried from a running saw or ?????

 

[DONLAWSON84]

Block the intake side of your carb and pull a couple times, it usually helps flush the lines out with the natural vacuum of the motor. Some carbs have an internal screen that supply the vacuum chamber to pull the fuel, I have found that and the float chamber clogged before.

 

[singinwoodwackr]

Was the last carb you tried from a running saw or ?????

No, both were non running, basically pts saws

 

[singinwoodwackr]

Block the intake side of your carb and pull a couple times, it usually helps flush the lines out with the natural vacuum of the motor. Some carbs have an internal screen that supply the vacuum chamber to pull the fuel, I have found that and the float chamber clogged before.

OK, tried that...taped off the intake and gave it 5 pulls...no joy.

 

[DONLAWSON84]

Next thing would be to talk dirty and slap it around a little, have you checked orientation and all the gaskets and covers? a small tear is a diaphragm would limit your vacuum to pull the fuel

 

[singinwoodwackr]

Next thing would be to talk dirty and slap it around a little, have you checked orientation and all the gaskets and covers? a small tear is a diaphragm would limit your vacuum to pull the fuel

Yea, first thing I double-checked...gasket and diaphragm placement.
I'm starting to wonder if these kits are bad...or...the wrong ones..
Everything matched what was there, diaphragm and gasket wise. But, it is possible the previous owner put wrong kits in them at some time, hence, throwing the saws out.
Next step may be to order OE kits based on the exact pt#s on the carbs since they are OE.

 

[Okie]

Does the saw ever do more than just pop if you give it a prime of gas in the carb throat?
(does it ever run for a few seconds with a prime?)

 

[Okie]

No, both were non running, basically pts sawsView attachment 982854View attachment 982855

Is this what you mean by pts saws?

PTS is a common, normal, and often adaptive response to experiencing a traumatic or stressful event. Common occurrences, like car accidents, can trigger PTS as well as more unusual events like military combat or kidnapping. Almost everyone who experiences a scary situation will show at least a few signs of post-traumatic stress. That’s because our brains are hard-wired to tell our bodies to tense our muscles, breathe faster, and pump more blood when we’re under intense stress. This is the “fight-or-flight” response that prepares your body to deal with a threat or challenge in the environment by pumping more blood and oxygen to your muscles, and it shuts down non-critical functions like digestion. This fight-or-flight response is a normal reflex during and sometimes even after a traumatic event, which is why PTS is considered a normal reaction and not a mental illness.

PTS Symptoms and Behaviors​

If you’re experiencing post-traumatic stress, your heart may race, hands shake, you may sweat or feel afraid and nervous. After the stressful event, you might avoid or be leery of engaging in that activity again, you may have a bad dream about the event you just experienced, or you may feel nervous in a situation that reminds you of the unpleasant event. Although they can be momentarily intense, symptoms of PTS usually subside a few days after the event and won’t cause any prolonged meaningful interference with your life. One positive outcome of experiencing PTS may be that you behave more carefully in a potentially dangerous situation in the future.

PTS Treatment​

Since post-traumatic stress is not a mental disorder, treatment is not required as the symptoms will likely improve or subside on their own within a month. However, you should talk to a healthcare provider if you feel troubled by your symptoms — if they’re interfering with your work, school, or relationships or if you’re engaging in reckless behavior such as drinking or using drugs to cope with symptoms.

 

[singinwoodwackr]

Does the saw ever do more than just pop if you give it a prime of gas in the carb throat?
(does it ever run for a few seconds with a prime?)

Just pops when some gas directly in the cold via sparkplug hole.
Haven't tried in the carb...will do so...
OK, tried that and it runs for a couple seconds, that's it.

 

[singinwoodwackr]

Is this what you mean by pts saws?

PTS is a common, normal, and often adaptive response to experiencing a traumatic or stressful event. Common occurrences, like car accidents, can trigger PTS as well as more unusual events like military combat or kidnapping. Almost everyone who experiences a scary situation will show at least a few signs of post-traumatic stress. That’s because our brains are hard-wired to tell our bodies to tense our muscles, breathe faster, and pump more blood when we’re under intense stress. This is the “fight-or-flight” response that prepares your body to deal with a threat or challenge in the environment by pumping more blood and oxygen to your muscles, and it shuts down non-critical functions like digestion. This fight-or-flight response is a normal reflex during and sometimes even after a traumatic event, which is why PTS is considered a normal reaction and not a mental illness.

PTS Symptoms and Behaviors​

If you’re experiencing post-traumatic stress, your heart may race, hands shake, you may sweat or feel afraid and nervous. After the stressful event, you might avoid or be leery of engaging in that activity again, you may have a bad dream about the event you just experienced, or you may feel nervous in a situation that reminds you of the unpleasant event. Although they can be momentarily intense, symptoms of PTS usually subside a few days after the event and won’t cause any prolonged meaningful interference with your life. One positive outcome of experiencing PTS may be that you behave more carefully in a potentially dangerous situation in the future.

PTS Treatment​

Since post-traumatic stress is not a mental disorder, treatment is not required as the symptoms will likely improve or subside on their own within a month. However, you should talk to a healthcare provider if you feel troubled by your symptoms — if they’re interfering with your work, school, or relationships or if you’re engaging in reckless behavior such as drinking or using drugs to cope with symptoms.

Uh, no, lol

 

[Oletrapper]

My 2 cents worth. lol,,,I have read the entire thread. It appears to me that the only thing that has not been checked/replaced is the intake block that the carb bolts to. May have a bad gasket/seal or a crack preventing proper impulse. The impulse passage could also be blocked/clogged.
I would go a little deeper and remove it and check for cracks, bad or faulty gasket. Make sure the impulse passage is open.
Pressure and vacuum checks are fine but all will leak down eventually. Anyway, hope you isolate the problem. Don't give up. Let us know what you find. OT

 

[Vintage Engine Repairs]

It’s time to go back over things you have checked to re confirm it, I’m confident you’ve overlooked something..

Think logically:

1). Test the fuel filter is clean
2). Test the fuel line holds pressure and isn’t collapsing or kinked
3). Disassemble the carb and using carb spray go through every hole in the direction the fuel does.
4). Use oem carb kit and ensure it’s assembled like the manual tells you (not how you found it) order of diaphragm and gaskets is essential. Ensure the flapper valves are sitting perfectly flat too!!!
5). Check the impulse drilling in the carb is clear
6). Add oil to the impulse hole or hose if present and see if it squirts out when turning the engine over
7). Test the impulse hose (if present) for leaks or for kinking
8).check the needle is not stuck,
9). Check the connection to the saw is good
10). Check the carb holds pressure and that it’s not warped anywhere.
11). Check the drillings and jet is clear and flows carb spray.

You will find your issue once you’ve done all this.

 

[alexcagle]

Although quickly diagnosed with a vacuum pressure test, when a crank bearing race comes apart, they usually rip the the adjacent crank seal. When that happens, the intake stroke will suck through the seal instead of the carburetor. Hence, no fuel.

 

[Old2stroke]

A quick test to determine if it's a carb problem or something else is to pressurize the input to the carb and make sure it holds pressure, then with the choke closed and the throttle open bring a running shot vac up to the engine end of the carb and see that the pressure drops right away. If it doesn't, there is something wrong with the items that open the inlet valve (diaphragm, control lever, etc.). CAUTION: make sure there is no fuel in the carb, the brushes in the shop vac motor will not be happy with fuel fumes .

 

[Okie]

I've noticed that QUITE OFTEN for just a few dollars more I can buy a Carb vs getting an OEM kit.

As suggested above check the impulse hole coming out of the engine and the impulse hose.

I'm suspecting that the issue IS NOT the carb. (after seeing all of the above)

Have you pressure/Vac tested the block?