ECHO CS 590 Hesitation

[Kenskip1]

So, here's what not happening. My 590 saw is just over a year old. When I got it I was using 87 octane with Amsoil at 40/1 The saw ran perfect with no hesitation what so ever. So after reading the owners manual it says 90 octane or better. So with the 91 and the same oil and ration the saw has developed a slight hesitation from idle. I have richened the mixture on the low side with the same results. My air filer is clean as is the gas filter. I am wondering if the 91 octane that has a higher flash point could be the cause. The 87 has a lower flash point and is easier to ignite. Am I barking up the wrong tree here? Otherwise the saw is perfect. Oils good and has plenty of grunt pulling a 20 B/C through oak. I just dislike the hesitation. BTW it has 175 pounds of compression. The muffler has been modified from the day I purchased it. Thanks, Ken

 

[Woodslasher]

I was told hesitation means lean, but since you said you richened it to no avail I'm not sure. Maybe clean/replace the plug and see if that helps. If it does, your flash-point theory may be correct.

 

[Wood Doctor]

I say go back to the fuel that the saw like you used last year. Two rules apply: (1) If it ain't broke, don't fix it and (2) Why question or try to improve success? Every owner of an Echo CS-590 that I know loves the saw.

 

[ammoaddict]

I can't see the octane making any difference. The flash point of gasoline is like 40 below zero. Octane is basically a resistance to pressure. I would try adjusting the low side again to see if it gets better. You can always try some more 87 and see what happens. It would be very interesting if it made a difference. Best of luck with it.

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[andyshine77]

The carbs on some of the newer Echo's are that way no matter how you tune them, they're too small IMHO. Try returning both the H&L and see what happens. And obviously make sure the lines are all good. If it's just a slight hesitation is just with it, or looking to the 600 carb.

 

[Kenskip1]

I say go back to the fuel that the saw liked to use last year. Two rules apply: (1) If it ain't broke, don't fix it and (2) Why question or try to improve success? Every owner of an Echo CS-590 that I know loves the saw.

Well, the owners manual specifies that they recommend 90 octane or better. I was using what I had on hand for my other saws. It was 87 octane.

 

[Kenskip1]

The carbs on some of the newer Echo's are that way no matter how you tune them, they're too small IMHO. Try returning both the H&L and see what happens. And obviously make sure the lines are all good. If it's just a slight hesitation is just with it, or looking to the 600 carb.

And if you go to the 'Tinmans" web site he did a carburetor swap from the 620 also a unlimited coil swap. Sorry but it is not the high side that has the problem. As stated it is an annoying hesitation just as you squeeze the throttle. For the amount of performance gained I have better things to do with my monies. Thank you for your information.

 

[andyshine77]

Correct easy upgrades.

The H and L work together to provide fuel at all speeds, most don't understand this. If you cannot compensate with tuning the L and everything else is good to go, the carb isn't providing enough fuel for smooth transition from idle to full throttle.

I have dealt with this on the 590 and other Echo's, they are very lean and have small carbs to meet emissions, as they do not have strato technology or Auto tune technology, this has affected some of the running characteristics. [emoji111]

 

[Kenskip1]

Correct easy upgrades.

The H and L work together to provide fuel at all speeds, most don't understand this. If you cannot compensate with tuning the L and everything else is good to go, the carb isn't providing enough fuel for smooth transition from idle to full throttle.

I have dealt with this on the 590 and other Echo's, they are very lean and have small carbs to meet emissions, as they do not have strato technology or Auto tune technology, this has affected some of the running characteristics. [emoji111]

The only problem that the saw had great throttle response when I was using 87 octane. Now using 91 I have this hesitation. The spark plug is light tan and I have great spark. I'm stumped.

 

[Wood Doctor]

Try another gallon of fuel mixed the same way with the gas you used last year. See if it makes a difference. That would give you a standard for comparison.

Hard to believe, but I once ran into a carb that refused to work with one saw's engine but worked perfectly with another that was the same model. The second one accepted both carbs. Things like this drive you bonkers.

 

[andyshine77]

The only problem that the saw had great throttle response when I was using 87 octane. Now using 91 I have this hesitation. The spark plug is light tan and I have great spark. I'm stumped.

Octane shouldn't do that, but go back to the 87 and see how she runs, nothing wrong with 87-89 octane in a saw. Low octane has more energy, so I guess it's possible if the carb is right on the edge of providing enough fuel.

 

[Ford3000]

The only problem that the saw had great throttle response when I was using 87 octane. Now using 91 I have this hesitation. The spark plug is light tan and I have great spark. I'm stumped.

I bet you would have the same issue if you started using that Aspen premix, it happened me, saw lost its kick, but still cuts well, I only use the Aspen as a backup fuel because it keeps a long time in the unopened can, but when I tested I found throttle response was slightly off. Go back to the old fuel and save yourself a headache for nothing, otherwise put on a bigger carb.

 

[ammoaddict]

The only problem that the saw had great throttle response when I was using 87 octane. Now using 91 I have this hesitation. The spark plug is light tan and I have great spark. I'm stumped.

There is no logical way that switching from 87 to 91 can cause running issues. But now I'm very curious. Please try the 87 again and let us know if it helps. If it does, I'm going to throw everything I thought I knew about gasoline out the window.

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[ammoaddict]

Octane shouldn't do that, but go back to the 87 and see how she runs, nothing wrong with 87-89 octane in a saw. Low octane has more energy, so I guess it's possible if the carb is right on the edge of providing enough fuel.

The following is copied and pasted from car and driver magazine:

In fact, octane has nothing to do with energy content or quality – it's a measurement of the gasoline's ability to resist engine knock. Higher octane denotes greater knock control.

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[Kenskip1]

I Will do this tomorrow. The 91 octane has a different smell to it. I simply wonder if it could be just bad gas? Anyway I will go back to square one tomorrow, Ken

 

[davidwyby]

High octane doesn’t get used as much so maybe it sat.


I tried higher octane and went back to low.

 

[huskihl]

The 91 could have more ethanol in it, which would make it run lean

 

[smokey7]

I bet diaphrams firmed up a little bit. Adjusting the carb as a whole from bottom up will solve this

 

[CR888]

Fresh volatile gas, tune saw so it don't stumble off idle.

 

[Kenskip1]

The 91 could have more ethanol in it, which would make it run lean

Huskihi, I put the 91 in it because this gas is supposedly ethanol free.