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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 28383
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I have a Deere 445 and it runs fine when cool but once it

Customer Question

I have a John Deere 445 and it runs fine when cool but once it gets hot it starts popping back through the throttle body I also noticed the red and green light stays on steady on the fuse panel
JA: I'll do all I can to help. Tell me a bit more about what's going on so we can help you best.
Customer: when mowing it does fine till it gets up to normal temp and starts missing and then will die you can start it rite back up but continues to miss and pop back through the throttle body I have another machine just like it and the indicator lights on the fuse panel only has a steady green light no red light on it and it runs great
JA: Is there anything else the Small Engine Technician should be aware of?
Customer: I have replaced the fuel pump did not help I have changed the coils did not help sometimes it won't act up and I can mow the whole yard no problem but the problem is getting worse
JA: I'm sending you to a secure page on JustAnswer so you can place the $5 fully refundable deposit now. While you're filling out that form, I'll tell the Small Engine Technician about your situation and connect you two.
Submitted: 1 year ago.
Category: Small Engine
Expert:  Curtis B. replied 1 year ago.

Try adjusting the valves! This engine needs valves adjusted occasionally. If valves are too tight, they start to leak as they warm up. Looks like lash should be ,010 inch on intake and exhaust on the FD620 engine. It may not be a sensor or fuel problem! And when engine starts to misfire, the yellow light comes on from exhaust sensor seeing a rich mixture. Worth looking at!

Expert:  Curtis B. replied 1 year ago.

Did you find the problem?

Customer: replied 1 year ago.
I thought the same thing so I did adjust the valves and they were a little tight but it did not take care of the problem its difficult to trouble shoot because when it acts up if you shut it off and start it backup it will run fine for a while before it acts up again sometimes it runs fine for 2 weeks no problem
Expert:  Curtis B. replied 1 year ago.

Intermittent problems, always hard to diagnose, but with it blowing back through throttle body, would seem to be spark occurring with valve not fully closed. May be valve sticking. But with it stopping when it is shutoff and restarted that does not fit. That leaves the spark occurring at wrong time. Do you have a spark tester, so you could test the spark on each cylinder when it is acting up? If spark gets erratic on one cylinder, you could have a bad trigger coil. This engine has two triggers, two coils and an igniter.

Customer: replied 1 year ago.
I will check that next
Expert:  Curtis B. replied 1 year ago.