ECHO CS 590

[Kenskip1]

Well here is the deal. I have had my 590 just around a year. I did a muffler mod and richened it up. However it has a slight hesitation from idle. I have richened the low side, but the slight hesitation is still apparent. I looked around the web and found that this saw has a accelerator pump. Is there a way to verify that the accelerator pump is working? Thanks Ken

 

[CR888]

Why not lean it out some to get the correct throttle response. Never understood the very 'common advice' that it's a must to richen jetting after a muffler mod. I usually end up having to lean it out some.

 

[Kenskip1]

Why not lean it out some to get the correct throttle response. Never understood the very 'common advice' that it's a must to richen jetting after a muffler mod. I usually end up having to lean it out some.

If I lean it out it gets worse.

 

[mountainlake]

I've had the carb apart, never saw a accelerator pump but maybe I misses it. Did you opening up the low a little more? I've had the boot between the carb and engine fail. Check by spraying some WD 40 or similar at the carb boot with it running being careful not to get it in the carb inlet. If it slows down the boot is leaking. Steve

 

[Kenskip1]

I've had the carb apart, never saw a accelerator pump but maybe I misses it. Did you opening up the low a little more? I've had the boot between the carb and engine fail. Check by spraying some WD 40 or similar at the carb boot with it running being careful not to get it in the carb inlet. If it slows down the boot is leaking. Steve

Thanks Steve but I have read someplace that this saw has a accelerator pump. I simply would like to get rid of this hesitation. And I did what you mentioned with carb cleaner. No change of engine speed. I went to ECHO web site and no accelerator pump was listed. Other wise it runs great. Has 175 pounds of compression. Just that hesitation bothers me. Ken

 

[GeorgiaVol]

Cleaned the air filter or replaced the fuel filter?

 

[Kenskip1]

Cleaned the air filter or replaced the fuel filter?

George, The saw has about 20 hours on it. If it was the gas filter it would be starving for gas at WOT. The air filter is clean. What I plan to do is whip up a fresh batch of mix. I will see if fresh mix makes an improvement. Older mix is harder to ignite so hopefully this will improve the hesitation situation. The saw has been sitting inside the hot garage all summer, so hopefully the fresh brew may help. (sort of like drinking warm flat beer) I am open to more suggestions.
I will add that before I started using the 91 octane I did not have this problem. I was using regular 87 octane and had instant throttle response. I am trying to piece the puzzle here. Seeing as 91 octane makes it harder for detonation, this means that the mix is harder to ignite, possibly causing my hesitation issue. Yes I am fishing here however hopefully someone will chime in. So hopefully tomorrow I will get a gallon of 87 gas mix it with Amsoil at 40/1 and see if the saw likes this any better than the 91. I will add that the 87 octane has a lower flash point that makes it easier for the saw to ignite. Comments are welcome,,, Ken

 

[Kenskip1]

yes it will

 

[CR888]

If your using old stale fuel well putting fresh volatile gas in the tank is where I'd start 1st.

 

[Kenskip1]

Well the problem has been solved. I dumped out the 91 octane and refilled the saw with fresh 87 octane mixed at 40/1 with Amsoil Saber.I allowed the engine to run at idle for a few minutes. Anyway now when I hit the throttle the saw jumps like it used to. I will attribute this to the 91 octane being old. I spoke with a friend and he told me that the 91 sits in the tank at the station for extended periods of time. It makes sense to me. Note, this was the cheapest fix on a saw that I had in years. Ken

 

[mountainlake]

I always use 91 with no ethanol up here in MN, the 91 gets more use in the winter from snowmobiles. Down in Missouri I'd bet it can sit a long time . Steve

 

[K-techcowboy]

Well the problem has been solved. I dumped out the 91 octane and refilled the saw with fresh 87 octane mixed at 40/1 with Amsoil Saber.I allowed the engine to run at idle for a few minutes. Anyway now when I hit the throttle the saw jumps like it used to. I will attribute this to the 91 octane being old. I spoke with a friend and he told me that the 91 sits in the tank at the station for extended periods of time. It makes sense to me. Note, this was the cheapest fix on a saw that I had in years. Ken

It is true that 91 doesn't get circulated as much as 87 but if the gas station does what there supposed to and having the tanks cleaned on a yearly basis it shouldn't be an issue. Now I have ran into some batches of bad 91 as well but it was do to water in the gas after days of hard rain. When water and gas separated the water sits at the bottom so in any small engine up to a motorcycle size even the smallest amount of water will effect its performance until the watery mixture is gone. I always go to a busy truckstop casino gas station cause they go through alot of fuel its well priced non eth. Always ran great in my motorcycles.