Need Help on Small Engine

[Scout Sport Fish]

All of a sudden my mo-ped has gone to ****. The engine is a Robin (EH035) and its running horrible. It wont start (recoil) unless you hold the throttle wide open. Even then, while holding it wide open its pushing idle RPM's. I cleaned the carb 4+ time and it still runs like crap. But when you hit the primer bulb it runs like a champ for all ove 1 second. Seems to be a fuel restriction problem like its to rich or somthing. Any suggestions?

PS, the carb has NO adjustment screws other than idle.

 

[Bob_VT]

Re: Need Help on Small Engine

Step 1 change the spark plug.

There might be a fuel diaphram that is shot or a carb gasket gone sounds like an air leak too.

 

[darrklim2]

Re: Need Help on Small Engine

Pushing primer bulb then works good for 1 second, sounds like fuel pump, unless it is gravity fed, then I would guess restriction in the fuel line or as said previously - bad diaphragm.

 

[KRS]

Re: Need Help on Small Engine

Does that Robin engine have the white or clear plastic round cylinder (1" tall) at the bottom of the carb housing? If it does, unscrew it, turn the fuel valve on (down) and let the fuel flow. Clean the white cyliner and reinstall it after you cleared out the line.

If it doesn't have it, find the fuel line from the tank to the carb and disconnect it, make sure you have good fuel flow.

I have a 4HP Robin engine and it runs great. Then one day I couldn't get it to keep running for NOTHING! I checked everything, even checked the spark plug (it was sparking!). I finally replaced the plug and the thing started on the first pull.... I was so frustrated at that point I could only laugh at myself.

Try and plug and see what happens!

KRS

 

[12Footer]

Re: Need Help on Small Engine

And then, if that doesn't werk....

Disconnect the exhaust pipe. If it runs great, replace or "modify" the exhaust pipe. Two-cycle engines have a nasty habit of gooping-up the exaust ports with carbon and unburnt oil. It looks for all the world like tar, and will cause the symptoms you describe -- but then again, Fuel pump, filter, or compression will also.

 

[rob711]

Re: Need Help on Small Engine

try 12 footers advice..i had a puch when i was 16 w/the same problem...although it had no primer bulb...wit no exhaust it would run good...neighbors did'nt like it though....i drilled some holes in the bottom of it that did the trick...or as stated above its a fuel restriction..good luck