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Troy-Bilt 4-Cycle Trimmer Won't Cold Start But Runs Amazing

Posted by hexabyte (My Page) on
Thu, Apr 22, 10 at 3:13

Hello all, I just joined the forum as I've been using this site extensively over the past few days trying to figure out the problem with my string trimmer and am totally at my wit's end with it.

Model: Troy-Bilt TB425CS Gas String Trimmer
Age: About 3 years old.


I recently pulled the trimmer back out of storage from the previous year to notice my fuels lines had disintegrated so I ordered OEM fuel lines including the fuel filter and installed them. Ever since, no matter what I do, I cannot get this thing to start without a lot of work and time. When I use the primer/purge bubble, I seem to catch a lot of air-bubbles in the fuel-lines. I have to spray cleaner into the carburetor to get it to even try, and every once in a while I will get lucky and it will continue to run just fine like it's brand new. When I get it to start up this way, It restarts first pull every time.

Solutions Tried:

1)Adjusted the idler so when it is started, it runs 100% smooth as can be.

2)Switched fuel lines between fuel entry/return.

3)Replaced the bubble for purging

4)Inspected exhaust & air-fins for blockages.

5)Temporarily took fuel filter off just to test starting.

6)Checked ignition switch connections.

7)Took carburetor apart to check for build-up, blockage.

8)Replaced spark-plug.

9)Tried purging, not purging, choking, half-choking, no-choke. (All combinations imaginable)

10)Put new gas in and checked oil.

11)Made sure there were no leaks in fuel lines.

12)Removed fuel lines from tank, purged air/gas out and reinstalled into tank.

Other Notes:

I just don't understand what could be going on. I should also note that the ignition switch used to work flawlessly, now has to be messed with (off, on, off, on) to get the unit to power off. When I use the cleaner to get this thing to initially start, it runs amazing which leads me to believe there isn't an engine or carb issue at least after it warms up well as it restarts like brand new. I also don't think it's an ignition issue/spark issue because carb cleaner will at least get it to try and start every time.

Any help or ideas would be greatly appreciated.

Follow-Up Postings:

RE: Troy-Bilt 4-Cycle Trimmer Won't Cold Start But Runs Amazing

You left gas in the carb for long time, even you vitually inspect the internal of the carb, it might not be good enough. Get SeaFoam and run a tankful and see what happen since you can somehow start it.

If you are going to leave gas in the trimmer for storage, use Stabil from now on. The way I store stuff is to empty the tank, run it dry, close the choke, prime the bulb, hold full throttle and start it and let it run to stop, and keep pulling while holding full throttle. This should pull all the gas out of the carb. THis work only on handheld trimmer etc.

RE: Troy-Bilt 4-Cycle Trimmer Won't Cold Start But Runs Amazing

Thanks for the response and tips. I took the carb completely apart, adjusted some things, cleaned it very well and made sure the throttle lever was working as intended (which required a minor adjustment) and the engine powered up without choke/much purging or pulling. Not sure if the cleaner residue helped make this happen, but every pull was a one-pull start afterwards. I will try and start it later tonight and update with my findings.

RE: Troy-Bilt 4-Cycle Trimmer Won't Cold Start But Runs Amazing


The engine still turns over just fine, so the carb obviously needed a thourough cleaning and the throttle lever needed some adjusting.

RE: Troy-Bilt 4-Cycle Trimmer Won't Cold Start But Runs Amazing

I am having the same problem with the very same string trimmer and I have tried pretty much everything you listed, can you elaborate more on the adjustments you made to solve the issue?

RE: Troy-Bilt 4-Cycle Trimmer Won't Cold Start But Runs Amazing

Just get some concentrated fuel cleaner and add some a few ounces to your fresh fuel . You may also have to adjust your jets and or clean them also . Try the fuel additive 1st .

RE: Troy-Bilt 4-Cycle Trimmer Won't Cold Start But Runs Amazing

hexabyte, Have you "Always" checked for fire when the engine w/n cold start? Have tried to cold start with all the kill switch components removed (to eliminate any faulty grounding)? loger

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