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View Full Version : ECHO Trimmer Fuel Problem


jud149
10-28-2009, 10:42 AM
It wants to die when giving in gas from idle. Sometimes it will die when idiling. If I adjust the carb by maybe just an eight of a turn on both the lo and hi screws, it will run fine for a while and then start doing the same thing again. I rebuilt the carb about a year ago and it was fine until recently. Any help would be appreciated.

jud149
10-28-2009, 12:10 PM
I spoke with ECHO tech and they said they recommend replacing the carb on such units after about 300 hrs. Mine has about twice that amount.

ed2hess
10-28-2009, 10:10 PM
What model trimmer.....I seldom see a need to replace a carb on Echo. How much use on this machine? Just be sure the ports are clean and fuel system is good meaning the filter and lines coming up. And do you have any leaks on the four gaskets? Spray carb cleaner on all those gasket while the unit is running to see if it makes a difference.

jud149
10-29-2009, 11:41 AM
What model trimmer.....I seldom see a need to replace a carb on Echo. How much use on this machine? Just be sure the ports are clean and fuel system is good meaning the filter and lines coming up. And do you have any leaks on the four gaskets? Spray carb cleaner on all those gasket while the unit is running to see if it makes a difference.

Thanks for your input. The model is SRM-1501. It gets used about once per week and is roughly 20 years old. I did have the carb apart again last week and blew out all ports. It ran better for about 1/2 hour and then I had to readjust the carb. All it needs is about 1/8 of a turn on the idle screw and it's okay again for a while and then the problem resurfaces. I'll try spraying the carb cleaner to see if it makes a diff. If it does run better, would you recommend rebuilding or new carb? Thanks again!

topsites
10-29-2009, 12:07 PM
Have you replaced the fuel filter inside the tank in recent years?

It's not hard to do but you do have to pull the tank, if I recall correctly.

I'm also assuming the air filter is clean, and the spark plug is good and gapped correctly.
By the way, if you pull the plug, replace it with a new one.

whoopassonthebluegrass
10-29-2009, 12:19 PM
Sounds like a fuel delivery problem. Just enough to keep it alive at idle, but not enough to really feed it.

madmower
10-29-2009, 12:22 PM
if you pull the carb take it to someone with a ultrasonic cleaning tank and let them clean the carb it sounds like you have some crap in the carb which gets sucked in one of the small pasages and causes the problem you discribe

bill

ed2hess
10-29-2009, 10:40 PM
I have good luck with rebuilding carb...did two echo today. And you don't need anything fancy to clean out port on carb it can be can of carb cleaner with pipe stems. I would be sure that both crank seals are in place and then I would replace all the gaskets...that is pretty old.

Brick One Lawns
10-29-2009, 10:45 PM
there are little rubber check valve type things inside the carbs. I was told that these valves go bad?, rot out?, or something due in part to using 87 octane gasonline. I was told to use 89 and I wouldn't ever have a problem again... just what I was told when I had to replace my carb on my echo hedge trimmer.

mowerknower
10-29-2009, 10:57 PM
sounds like an air leak. could have a seal or gasket leaking. Pretty tough to justify putting much money into a 20 yo echo

whoopassonthebluegrass
10-29-2009, 11:13 PM
there are little rubber check valve type things inside the carbs. I was told that these valves go bad?, rot out?, or something due in part to using 87 octane gasonline. I was told to use 89 and I wouldn't ever have a problem again... just what I was told when I had to replace my carb on my echo hedge trimmer.

I'm gonna call B.S. on that one. Gas is a mixture of octane and heptane (which is a reference to carbon chains).

87 Octane means 87% Octane, 13% Heptane.
89 Octane means 89% Octane, 11% Heptane.

The performance difference between the two is a matter of compression. As fuel is jetted into the cylinder and the cylinder comes up (compresses) the fuel, there's a point at which the compression would build so much heat/pressure that the fuel will combust (without the spark). This is how diesels work.

The reason for varying octanes is because heptane ignites readily, while octane doesn't. By blending the two, you create a tolerance to compression. Thus, "normal" motors with typical compression rates (8:1 for example) call for 87 octane - because there's no need for higher compression tolerances in that motor. On the other hand, though, high performance motors often have higher compression ratios - which calls for more compression-tolerant fuel...

This, by the way, is the science behind why running higher octane fuel in a motor than the manufacturer calls for, is nothing but a complete waste of money.

Anyhow, getting back to the part where I give your "friend" with the sage advice the "stink eye" - the motor is designed to handle octane and heptane just fine. Those parts aren't failing as a result of 2% more heptane. That's just silly.

Now if you're running ethanol fuel, that's another issue. :waving:

ed2hess
10-30-2009, 10:13 PM
there are little rubber check valve type things inside the carbs. I was told that these valves go bad?, rot out?, or something due in part to using 87 octane gasonline. I was told to use 89 and I wouldn't ever have a problem again... just what I was told when I had to replace my carb on my echo hedge trimmer.

There check valves are made of rubber and since this unit is very old they were probably bad. I replace them about the 4 year point because the carb is the first major thing to fail on trimmers. So I put in a $11 rebuild kit and they are good to go. Just finished one tonight and it had sticking needle valve. I could not see a reason for sticking but slide a used one from another build and the unit took off.

mowerknower
10-30-2009, 10:56 PM
How the f do you replace the check valves?

madmower
10-31-2009, 03:38 AM
check valves are non replacable i think you are refering to the diaphram and fuel pump kit the check valves are deep in the carb body


bill:ukflag:

unkownfl
10-31-2009, 12:56 PM
I'm gonna call B.S. on that one. Gas is a mixture of octane and heptane (which is a reference to carbon chains).

87 Octane means 87% Octane, 13% Heptane.
89 Octane means 89% Octane, 11% Heptane.

The performance difference between the two is a matter of compression. As fuel is jetted into the cylinder and the cylinder comes up (compresses) the fuel, there's a point at which the compression would build so much heat/pressure that the fuel will combust (without the spark). This is how diesels work.

The reason for varying octanes is because heptane ignites readily, while octane doesn't. By blending the two, you create a tolerance to compression. Thus, "normal" motors with typical compression rates (8:1 for example) call for 87 octane - because there's no need for higher compression tolerances in that motor. On the other hand, though, high performance motors often have higher compression ratios - which calls for more compression-tolerant fuel...

This, by the way, is the science behind why running higher octane fuel in a motor than the manufacturer calls for, is nothing but a complete waste of money.

Anyhow, getting back to the part where I give your "friend" with the sage advice the "stink eye" - the motor is designed to handle octane and heptane just fine. Those parts aren't failing as a result of 2% more heptane. That's just silly.

Now if you're running ethanol fuel, that's another issue. :waving:


You can have compression ratios less the 8to1 and still have detonation. Timing and combustion chamber designs come into play as well. If the manufacture use the manufactures suggested octane level and nothing less. I have a 9.5to1 engine which runs fine on 87 as well.

whoopassonthebluegrass
10-31-2009, 03:04 PM
You can have compression ratios less the 8to1 and still have detonation. Timing and combustion chamber designs come into play as well. If the manufacture use the manufactures suggested octane level and nothing less. I have a 9.5to1 engine which runs fine on 87 as well.

Yes, good point. There are several factors involved (my compression ratios were just an example, not a limit), but what you pointed out: the engineers knew the minimum rating to avoid "pinging" (i.e. premature detonation)- is all that's important to understand.

Brick One Lawns
11-05-2009, 12:32 PM
maybe it was the ethanol part he was trying to tell me caused the valves to go bad. I dunno. I know the valves can't be changed and i had to buy a new carb.

ed2hess
11-05-2009, 07:51 PM
sounds like an air leak. could have a seal or gasket leaking. Pretty tough to justify putting much money into a 20 yo echo

Two crank seals and four gasket ......$12. Sometimes it is just to prove tha you can get em going.