362 hard starting

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Big_Al

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Have a 362, it's several years old and been well used. It's been hard to start when warm the last couple times out. Yesterday after running it for 20 minutes I opened the gas cap & noticed air bubbles coming up thru the gas? Any ideas on what can cause this? Could it cause the hard starting?
Thanks
 
Have a 362, it's several years old and been well used. It's been hard to start when warm the last couple times out. Yesterday after running it for 20 minutes I opened the gas cap & noticed air bubbles coming up thru the gas? Any ideas on what can cause this? Could it cause the hard starting?
Thanks
Your tank vent is not working.
The fuel is under vacuum and is boiling.
This also explains hard starting when warm.
 
Have a 362, it's several years old and been well used. It's been hard to start when warm the last couple times out. Yesterday after running it for 20 minutes I opened the gas cap & noticed air bubbles coming up thru the gas? Any ideas on what can cause this? Could it cause the hard starting?
Thanks

What you are seeing and experiencing with gas bubbling is actually the fuel boiling and vapor lock in the carburetor. Do a search on "Fuel geyser" to learn more. It is a known issue in hot weather exacerbated by using "winter" formulated gas in warmer temperatures. This is NOT a vent problem. New design tank vents are designed to let air in but NOT to let fuel vapor and pressure out. EPA doesn't like letting unburned hydrocarbons loose in the atmosphere.

About all you can do is use current season gas, don't let the saw sit in the sun, and let the saw idle for a minute before shutting it off to dump excess heat.
 
What you are seeing and experiencing with gas bubbling is actually the fuel boiling and vapor lock in the carburetor. Do a search on "Fuel geyser" to learn more. It is a known issue in hot weather exacerbated by using "winter" formulated gas in warmer temperatures. This is NOT a vent problem. New design tank vents are designed to let air in but NOT to let fuel vapor and pressure out. EPA doesn't like letting unburned hydrocarbons loose in the atmosphere.

About all you can do is use current season gas, don't let the saw sit in the sun, and let the saw idle for a minute before shutting it off to dump excess heat.

Ok, I can try letting it idle before shutting it off. I try to keep it & myself in the shade when possible & it's fresh gas in the saw.
Thanks
 
Ok, I can try letting it idle before shutting it off. I try to keep it & myself in the shade when possible & it's fresh gas in the saw.
Thanks
One other thought... I don't know if this is a carburated or M-tronic saw but if it is running a bit lean it will also run hotter. Richening it up a bit should help the saw run cooler as will a muffler mod and re-tuning.
 
What you are seeing and experiencing with gas bubbling is actually the fuel boiling and vapor lock in the carburetor. Do a search on "Fuel geyser" to learn more. It is a known issue in hot weather exacerbated by using "winter" formulated gas in warmer temperatures. This is NOT a vent problem. New design tank vents are designed to let air in but NOT to let fuel vapor and pressure out. EPA doesn't like letting unburned hydrocarbons loose in the atmosphere.

About all you can do is use current season gas, don't let the saw sit in the sun, and let the saw idle for a minute before shutting it off to dump excess heat.
Perhaps and perhaps not...
Fuel will readily boil in a vacuum.
The complaint stated bubbles not any geyser effect.
OP - the next time you’re having trouble warm starting open the fuel cap and then put it back on and try starting.
If the problem abates I’d be inclined to replace the tank vent.

I’m not particularly rigid about my diagnosis because I don’t have the saw in my hands. Good luck.
 
One other thought... I don't know if this is a carburated or M-tronic saw but if it is running a bit lean it will also run hotter. Richening it up a bit should help the saw run cooler as will a muffler mod and re-tuning.
It's a carb saw, bought it the first year the 362 came out.
 
Perhaps and perhaps not...
Fuel will readily boil in a vacuum.
The complaint stated bubbles not any geyser effect.
OP - the next time you’re having trouble warm starting open the fuel cap and then put it back on and try starting.
If the problem abates I’d be inclined to replace the tank vent.

I’m not particularly rigid about my diagnosis because I don’t have the saw in my hands. Good luck.

There was a fair amount of bubbles in the gas. After it didn't want to start I opened the cap to be certain it had enough fuel & noticed the bubbles. It did look kinda like it was boiling but after I filled tank (was half empty) it was still bubbling. Gas in tank was warm but not hot.
It still didn't want to start after filling up tank .
 
There was a fair amount of bubbles in the gas. After it didn't want to start I opened the cap to be certain it had enough fuel & noticed the bubbles. It did look kinda like it was boiling but after I filled tank (was half empty) it was still bubbling. Gas in tank was warm but not hot.
It still didn't want to start after filling up tank .

That’s really good information....

Let’s assume that vapor lock is the issue. If so, it would take some priming pulls to get fuel into the carb. The fuel in the tank would make its way through the filter, up the line to the carb, through the diaphragm and back out through the return line and back into the tank.
So it would take a few pulls to get the carb properly primed, etc.

Now let’s say the issue was negative tank pressure from a bad vent.
The same things would happen after you refilled the tank, fuel would travel to and from the carb in order to prime it.

So how would you know which scenario it actually was?

Well if it were a tank vent causing a vacuum issue inside the tank, you could hear air getting sucked in as you opened the cap. You might even feel resistance as you pull it.

If it were fuel boiling off to vapor I’d expect positive pressure when you opened the cap. The sucking or blowing do sound a bit different from each other.

Next time you open the tank before a warm start see if you can notice anything pressure or vacuum wise with the cap.
 
That’s really good information....

Let’s assume that vapor lock is the issue. If so, it would take some priming pulls to get fuel into the carb. The fuel in the tank would make its way through the filter, up the line to the carb, through the diaphragm and back out through the return line and back into the tank.
So it would take a few pulls to get the carb properly primed, etc.

Now let’s say the issue was negative tank pressure from a bad vent.
The same things would happen after you refilled the tank, fuel would travel to and from the carb in order to prime it.

So how would you know which scenario it actually was?

Well if it were a tank vent causing a vacuum issue inside the tank, you could hear air getting sucked in as you opened the cap. You might even feel resistance as you pull it.

If it were fuel boiling off to vapor I’d expect positive pressure when you opened the cap. The sucking or blowing do sound a bit different from each other.

Next time you open the tank before a warm start see if you can notice anything pressure or vacuum wise with the cap.
I'll check it next trip up to the property, thanks!
 
Went up today and cut a couple cords. The temperature was 15 degrees cooler than last trip and the saw started fine every time. There is a little noise when I open the gas cap, seems like a little pressure built up.
 
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