Makita 6401

[timq585]

I have a Makita 6401 that is driving me a little crazy. I just got it back from the dealer after taking it in because it wouldn't start after it got hot. It would start and run right after you shut it off, but if you let it sit for 3-5 minutes it will not start. The only way I have had it start after letting it sit for 5 minutes after it was previously running was to remove the air filter and drop a few drips of gas into the carb. My dealer replaced the carb on my saw, and I was hoping that solved the problem, but didn't... Any suggestions as to what may be causing this? Also when I come off full throttle after the cut, if I want to put the saw down and let it idle for a minute while I reposition a log for a cut, sometimes it will die. I put a new plug in, and I run Dolmar oil. Thanks in advance.

 

[Paragon Builder]

Having a similar issue with my dolmar 6400. It starts but my arm is pretty tired after it does. I bought a fuel line and impulse line but haven't done them yet.
Sounds like if fuel in the carb helps it start it's def a fuel issue.
Does choking it help?
Maybe a tank vent?
Has it always been this way?
I'm remembering someone told me of one that had problems and the impulse port wasn't drilled out completely in the cylinder. Fixed it and ran beautiful.

 

[CR888]

Sounds like a vapour-lock problem. Purging primer bulb to get air out and fuel in fixes it but the 6400 don't have primer bulb from memory (should know as l have one). Another way l have found works but is NOT a recommended starting procedure is to hold the throttle wide open whilst pulling starter at same time. I bet if you let your saw cool down it starts normally? It happens to one of my pole saws and is pita.

 

[Chris-PA]

I have major issues with vapor lock on most of my saws, as I use E10 fuel. E10 boils more easily than real gasoline. It is especially bad early in the year if they still have winter blend fuel in the system, as that adds butane to make the fuel vaporize easier in cold weather. A purge bulb does not help either, as when you release the bulb and it tries to pull more fuel by dropping the pressure the fuel just boils. Try starting it on full choke even though it is hot. If it fires it's a vapor lock problem. Sometimes it takes me a long time to nurse it back to running even using full choke - I've had a hot saw sit there running on full choke for quite a while!

 

[Paragon Builder]

Sounds like a vapour-lock problem. Purging primer bulb to get air out and fuel in fixes it but the 6400 don't have primer bulb from memory (should know as l have one). Another way l have found works but is NOT a recommended starting procedure is to hold the throttle wide open whilst pulling starter at same time. I bet if you let your saw cool down it starts normally? It happens to one of my pole saws and is pita.

So is this caused by overheated fuel? Anyway to fix this? Heat shield or something?

 

[Paragon Builder]

I have major issues with vapor lock on most of my saws, as I use E10 fuel. E10 boils more easily than real gasoline. It is especially bad early in the year if they still have winter blend fuel in the system, as that adds butane to make the fuel vaporize easier in cold weather. A purge bulb does not help either, as when you release the bulb and it tries to pull more fuel by dropping the pressure the fuel just boils. Try starting it on full choke even though it is hot. If it fires it's a vapor lock problem. Sometimes it takes me a long time to nurse it back to running even using full choke - I've had a hot saw sit there running on full choke for quite a while!

Great info thanks!
So ethanol free fuel would fix this?

 

[Chris-PA]

So is this caused by overheated fuel? Anyway to fix this? Heat shield or something?

I take two saws, try to run them out of fuel before stopping if possible, and set the saws and the fuel in the shade. It's a PITA.

I've been thinking about some way to make a fuel cooler, but when the saw is off it will just heat soak.

 

[Chris-PA]

Great info thanks!
So ethanol free fuel would fix this?

Summer blend non-E would certainly help. But I'm not driving further than the nearest gas station for my fuel, so I'm stuck with it.

 

[Paragon Builder]

I take two saws, try to run them out of fuel before stopping if possible, and set the saws and the fuel in the shade. It's a PITA.

I've been thinking about some way to make a fuel cooler, but when the saw is off it will just heat soak.

Sweet! Now I have an excuse for multiples of my saws!!![emoji12]

 

[Paragon Builder]

Summer blend non-E would certainly help. But I'm not driving further than the nearest gas station for my fuel, so I'm stuck with it.

I don't know anywhere around to get any. Besides canned fuel that is.

 

[Cope1024]

I take two saws, try to run them out of fuel before stopping if possible, and set the saws and the fuel in the shade. It's a PITA.

I've been thinking about some way to make a fuel cooler, but when the saw is off it will just heat soak.

My old Poulan Super25 was real bad about heat soak if you ran it dry.

 

[Chris-PA]

My old Poulan Super25 was real bad about heat soak if you ran it dry.

Clearly some saws are worse than others. Probably depends on how long the lines are, how hot the lines and carb get, etc. Some of mine are just impossible to start again when this happens, and some can be nursed back. You'd think the ones with the tank in the handle would be better, but it doesn't always seem so. Most of my saws have carbs that are mounted to the cylinder with rigid blocks - I wonder how saws with rubber boots fare, and if they are more immune?

 

[Cope1024]

Clearly some saws are worse than others. Probably depends on how long the lines are, how hot the lines and carb get, etc. Some of mine are just impossible to start again when this happens, and some can be nursed back. You'd think the ones with the tank in the handle would be better, but it doesn't always seem so. Most of my saws have carbs that are mounted to the cylinder with rigid blocks - I wonder how saws with rubber boots fare, and if they are more immune?

I always thought it was because the tank was metal. ???

 

[Chris-PA]

I always thought it was because the tank was metal. ???

Apparently not - my plastic chassis clamshell saws with the tank in the chassis do it, as well as some mag cased saws with separate plastic tanks in the handle. I don't have any saws with metal tanks. My guess it that the carb and or lines are where the fuel is boiling.

 

[pennsywoodburnr]

Chris, I found a Gulf gas station near me that sells non ethanol gas. Plus I use StarTron. Those two things helped immensely. Before that I had to fart around with my saws to coax them back to life after letting them sit for a couple minutes. Man, that got old fast.

 

[Paragon Builder]

Most of my saws have carbs that are mounted to the cylinder with rigid blocks - I wonder how saws with rubber boots fare, and if they are more immune?

These makita/dolmars have a rubber boot....

 

[Paragon Builder]

And I've never had that issue on any of my other saws. Of course I don't even know if that's my issue yet, or if it's the op's issue.

 

[angelo c]

Chris, I found a Gulf gas station near me that sells non ethanol gas. Plus I use StarTron. Those two things helped immensely. Before that I had to fart around with my saws to coax them back to life after letting them sit for a couple minutes. Man, that got old fast.

Chris,
there was a station near the airport ( i think on either 'airport' or 'MacArthur' road) that sold ethanol free. It was there last year

 

[buzz sawyer]

I was having this problem in hot weather with my MS361 (yes, you read that correctly). It helped to let it idle for a couple minutes after cutting to cool down a little.

 

[timq585]

Thanks guys for the replies, I just recently went to ethanol free gas, its sold near me available in 91 octane. I have tried full choke but still wouldn't fire. If I let it cool down it fires right up. How do you know if the vent works in the tank?