GX630 starting issues

Normally I choke the machine and start at half throttle per instructions. This usually works but lately it’ll run for about ten seconds then instantly shut off, no sputtering. Doesn’t matter if the ball valve on my pressure hose is open or closed.

It starts right back up again, then shuts off a second time. Third time is a charm usually and it runs fine after.

Couple of things, should I choke it longer than a few seconds, and I noticed there is zero gas in the fuel filter until it’s been running a bit.

Full throttle on start up. Full choke. Even if it’s warm. Filter should have a little fuel in it but it will probably never be full

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Pull off the air filter, start the motor, and when it starts to die spray a short burst of starter fluid in the intake. If it revs back to life, you’ve got a fuel delivery issue. To me it sounds like trash in a jet or a sticking float valve

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Start with replacing the fuel filter… If it continues id clean the needles on the carb


Thing is, it just suddenly quits like the ignition cuts off.

I’ll try the full throttle thing William suggested and go from there, change the filter as well.

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Oh like it stops immediately?! I was thinking you meant it dropped off over a couple seconds. A hard stop is something else, honestly I haven’t experienced that one yet. If William’s advice doesn’t fix it, maybe disconnect everything from the output and see how it runs totally unloaded.

If your idle jet is clogged, the main jet will suck the bowl dry and kill the engine after a few seconds. The vacuum will refill the bowl and let you restart, over and over.

I’m always a huge fan of pulling the carb and cleaning the heck out of it, it’s fixed my problems 90% of the time

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Yup, stops instantly like someone shut it off. Wait a few seconds and it starts up fine and dies again.

Its fuel related… Just open up the carb and clean it… done

If everything carb related mentioned above seems in order, look into the wiring and fuel solenoid it must have 12V at all times in order for the gas to not be shut off. It has a piston that is spring loaded attached to an electromagnet. If the electromagnet is not working correctly or is intermittently, then the gas to the carb will be shut off or turned on intermittently, they can also gum up with crappy fuel. Might also pay to check the box that holds the key, choke, and throttle has a ground wire that grounds to the engine, check for corrosion, you run an enclosed trailer right?. I’m also assuming your oil level is correct.


Ensure oil level is correct, and take into consideration that the engine/trailer is level. You might just be ever so slightly low on oil.

My GX690 did this exact same thing, it was just the low oil sensor shutting it off. You will see the red light on by the ignition switch. If the oil level was anywhere below completely full, it would happen any time my trailer was even slightly off level.

I will definitely check that! I remember reading somewhere to fill it to half, maybe that’s why.

Fuel tank venting problem ? maybe tray start with tank cover removed. I know some people had problem with tank venting return line.

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Think this may be the culprit.

Thanks for all the suggestions!


Big dummy lol

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omg :man_facepalming:t3:


How have you let it go that low? A bone dry dipstick doesn’t happen over Night you would see it on the floor before your engine wouldn’t start, am i a fool for thinking you’ve never checked oil level?

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I don’t know where it’s going. It has about 20 hours since the oil change and it was a little above half.

Make sure it’s all the way up to - and not over - the second hole from the top of the dipstick.

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For other “big dummies”, before starting your machine you should do these things:

  1. Make sure it has fuel in it. (Insert Carl “It ain’t got no gas in it” voice here.)

  2. Check your oil level. It should be at the uppermost hole in the dipstick.

  3. Check your air filter. It takes all of 30 seconds and is the most overlooked maintenance item on any small engine.

  4. Check your pump oil level. Most have sight glasses. Some have dipsticks. If you have a dipstick just make sure it is at the top line.

  5. Make sure there is open flow from buffer to pump, pump to unloader, unloader to reel, reel to end of hose. Don’t start your machine with a gun attached or ball valve in closed position.

  6. Kick the tires and light the fires, big boy.