GX390 Idles, Won't rev

[Cdrew11]

Like the title says I've got a GX390 that runs, but now I'm having trouble getting it to rev. It starts and idles fine but it only revs when put on the choke. Using the throttle causes it to die...take my hand off the throttle, it idles just fine. I took out the spark plug and it's black. I was told that the engine is running too rich.

Any advice?

 

[71dodge]

try your air/ flow mixture screw on the carb

 

[Strigoi]

make sure it doesn't have a clogged jet either.

 

[Cdrew11]

just as a side note, It idles at low RPM with a low choke. Opening the choke causes the engine to rev.

71Dodge, where might that screw be?

 

[Cdrew11]

How might I be able to check for a clogged jet?

 

[Cdrew11]

Anybody?

 

[71dodge]

just as a side note, It idles at low RPM with a low choke. Opening the choke causes the engine to rev.

71Dodge, where might that screw be?

im not sure i was thinking of my briggs with the screw on the side :doah:

 

[grip9010]

Take the bowl off and blow the main jet out with carb cleaner or air gun. my gx 390 did the same thing i jetted the carb and runs great now.Do u know how to jet the carb

 

[Cdrew11]

Take the bowl off and blow the main jet out with carb cleaner or air gun. my gx 390 did the same thing i jetted the carb and runs great now.Do u know how to jet the carb

Ehh that would be a no.

 

[Cdrew11]

Problem solved guys, It turns out that the stock throttle system made the throttle fully open. I changed the spring and moved the cable and everything worked right as rain.

Once I got the thing running though I ended up totaling my comet 40 series belt so...Dang.

Thanks for all the help regardless.

 

[Cyanide]

its running way too lean thats why the spark plug is black also

 

[Strigoi]

its running way too lean thats why the spark plug is black also

a lean condition makes the plug white. if it's rich it will be black.