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JohnF2015
JohnF2015, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1080
Experience:  Owner/Service Technician at S & J Small Engines
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Can't get my trimmer started. I've got pre-packaged gas that

Customer Question

Can't get my trimmer started. I've got pre-packaged gas that I've used in the trimmer since I've bought it. So, the ratio should be correct. I just replaced the spark plug. But, I pull and pull and pull and nothing.
Submitted: 1 year ago.
Category: Small Engine
Expert:  JohnF2015 replied 1 year ago.

Hi, my name is ***** ***** I will be assisting you.

When was the last time that the machine was run?

Do you know if you are getting spark to the plug?

Customer: replied 1 year ago.
It has been used within the last 30 days. It sounds like it gets and occasional spark.
Expert:  JohnF2015 replied 1 year ago.

Thinking back to the last time you ran the machine, were you having any issues?

Can you remove the air filter cover, spray a little carburetor cleaner or fuel into the throat of the carburetor and see if it will start then?

Customer: replied 1 year ago.
Once the trimmer warms up a little, it always runs better. Other than that, it worked as it always has. I don't have any carb cleaner. Should I use mixed fuel to clean or plain gas?
Expert:  JohnF2015 replied 1 year ago.

I would used mixed.

Customer: replied 1 year ago.
I've done some cleaning. It didn't appear to be very dirty. After listening closer, it is sparking as best I can tell.
Expert:  JohnF2015 replied 1 year ago.

With the air filter removed, did you put some fuel directly into the carburetor throat and try to start it? If not, try to do so and see what happens.

Customer: replied 1 year ago.
Ok, I've tried that. Still sounds the same. Nice purr, but not starting.
Expert:  JohnF2015 replied 1 year ago.

Okay, we need to check to see if you are getting spark to the plug. Do you have a spark tester?

Customer: replied 1 year ago.
Sorry, I don't have one of those.
Expert:  JohnF2015 replied 1 year ago.

That's okay. You can still check for spark it is just a little harder to do. You will need to remove the spark plug from the cylinder, attach it back to the plug wire, ground the base or threads to the cylinder and crank the engine, watch to see if you get a spark to the plug. If not then we just found the reason that the machine is not starting, if it is then we will move on to another possible problem.

Customer: replied 1 year ago.
ok, verified sparking.
Expert:  JohnF2015 replied 1 year ago.

Since you are getting spark then I would recommend doing a compression test to see what kind of compression you have. You need at least 90 psi in order to get the engine to start, if it is lower than that it will not run.

Do you have a compression gauge or maybe know someone that does?

Customer: replied 1 year ago.
Sorry, I don't have one of those either. I'll check with the neighbors. Is there any "homegrown" work arounds for one of those?
Expert:  JohnF2015 replied 1 year ago.

Not really, we need to be accurate on this reading in order to be able to proceed.

Customer: replied 1 year ago.
ok, I've verified the compression. What next?
Expert:  JohnF2015 replied 1 year ago.

What was the compression reading?

Customer: replied 1 year ago.
100
Expert:  JohnF2015 replied 1 year ago.

What kind or brand of spark plug do you have in the machine right now?

Customer: replied 1 year ago.
Champion. I replaced it with the same make/model that was working previously.
Customer: replied 1 year ago.
Are you still there?
Expert:  JohnF2015 replied 1 year ago.

Since you know that you have spark to the plug, the compression is 100 psi, and by spraying fuel into the throat of the carburetor, this thing should be running.

The only other thing that I can think of is if the cylinder walls are damaged which can give us a misleading compression reading but it would also cause the unit to not pull fuel into the cylinder like it should. Can you remove the spark plug, shine a light down into the cylinder and see if you can tell what the walls of the cylinder look like. It can be hard to see, sometimes you can take a small screwdriver and run around the walls to see if you can feel any damage or scratches in the wall.

Customer: replied 1 year ago.
cylinder walls looks look great.
Expert:  JohnF2015 replied 1 year ago.

One other question, after pulling the machine a few times and it not starting. Is the spark plug wet with fuel?

Customer: replied 1 year ago.
It just started!!!!!!!!!!!!!!!! It ran very roughly at first, and wouldn't engage the trimmer. But, after some persistence, it finally kicked into high gear and was running wide open! I don't think it has every ran at that high of RPMs!
Expert:  JohnF2015 replied 1 year ago.

It sounds like you may have had the engine flooded, which would make it very difficult to start. After sitting for a little while it would dry out and then you could start it.

Did it begin to run properly? RPM come down to normal.

Thank you is has been a pleasure to assist you.

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