Would like to rebuild a 3HCPSE25 trimmer motor-do

You can get a rebuild kit from PartsBuggy.com. Just go to their cross-referencing page and enter the model # from your carburetor (it should be stamped into the body of the carburetor), NOT the trimmer model #, and you'll be given all the available kits for it.

Look on the body of your carburetor. There should be a set or two of numbers molded into it. Take these #s (they're the model # of your carburetor) and enter them into the Cross-Reference Page on PartsBuggy.com's website. If there is a kit available for the carburetor, you'll find it there.

A new fuel filter with new fuel lines and a rebuild kit for the carburetor should do it. You may even be able to get away with just the gasket and diaphragm kit for the carburetor. It is cheaper than the complete rebuild kit if you choose. Run synthetic oil and these things will last a good long while.

You probably know that it may need a rebuild kit with the new gaskets and diaphragms in it. It is quite possible a kit exists for it even though it is antique. Is it a Walbro or a Zama? I will send you to a tutorial by Zama on tuning a 2 stroke carb which includes your mixture screw settings. If you need help finding a rebuild kit or just a gasket w/diaphragms kit, please post back. I will be glad to assist.

http://www.zamacarb.com/tipspage.html

The carburetor needs a G and D kit (gasket and diaphragm kit) or the L speed mixture screw (the one closest to the engine) needs to be opened about 1/8-1/4 of a turn. In lieu of that, the carburetor may need to be removed and cleaned. That is always mandatory before installing any rebuild kit.

The carburetor needs to be removed and inspected. The malfunctions possibly indicate the need for a repair kit. I've been unable to locate your exact model, but if it has the 2-Stroke engine (gas/oil mix), then you will at the very least..need a gasket and diaghragm kit installed per inspection. There is the possibility that the carburetor needs a complete rebuild and would require the complete rebuild kit. Remove the gas lines (after draining gas). Remove the carb and inspect the screws and tightness of the screws in the 2 end covers. Are the screws tight? If not tighten them up and reinstall, trying to restart the machine. Post back if needed.

Trimmers are know to have problems when left with old gas in tank. They use a little diaphragm to pump fuel, with two little flappers in a gasket that act like check valves. This rubber gets wrinkled up and the check valves won't close. Buy a carb rebuild kit either online or through your local power equipment dealer and rebuild it. There are only about 5 parts in the kit.

most modern carbies have fixed jets.some you can pry off the caps and adjust,but usually if you need to adjust carbie,youve got other problems.stale fuel,not enough compression,vaccuum leak,spark plug faulty[oiled up]carb gaskets letting in air,needle valve adjustment causing diapragm to not open it enough.used the wrong gaskets in the kit[sometimes they have different model gaskets in one kit

It is a Briggs and stratton engine.

carb needle probably stuck you may needto take of carb and gentle clean it with carb spray but be carefull the gaskets are very thin if you tear them you must buy a $15 carb rebuild kit