530 troubleshooting help requested

Prior to mid last year, it would start right up and run very well. It would run best with the choke pulled out about � of the way. It ran well under load but I did notice a lot of carbon build up on the spark plugs.

Last year it started to run real rough and start much harder. I would have to have to crank for some time to get it to fire and eventually it would start. I also would have to change the plugs to get it started on several occasions. It has gotten worse and started to backfire and cough on a regular basis. I can not load it up for any length of time without a lot of backfiring and coughing.

Initially I adjusted the load screw and really saw no improvement in the backfiring. Just last weekend I tried to adjust the idle screws, thinking it was running rich. I had a difficult time setting the idle with one plug shorted. I followed the process that I had found on this site from back in 2005. It seemed like it would be fine and I would short the other plug the engine would not run smoothly or it would die. I cleaned the points and replaced the cap and rotor last year and saw no real improvement. I have changed the oil in the air cleaner as well.

I am beginning to wonder what I am missing. Could it be trouble with the float ? With the coil? Should I soak the carburetor in cleaner? I am looking for some advice on other areas to investigate. I am new to hobby and need some help. Thank you for your input.

One other related question, can someone recommend the best JD sickle mower for the 530? Are there models I should avoid?

Take the automatic fuel shut off assy. off and clean it out they have small passages that seem to collect junk and put in new diaphrams while in there.

And if it were mine after all the above I'd go ahead clean the carb. out and freshen it up and check it over. If you can do the work yourself it won't cost much and will save alot of headaches years down the road.