John Deere mower won't prime

18 years ago

I have a John Deere JS63 walk behind mower 6.5 hp. The primer bulb does not seem to be sending gas. The mower will not start, but will run for a few seconds if I put gas directly into the primer bowl. My air filter needs to be replaced, but I don't know if that has anything to do with it. I have no idea how to fix a lawn mower, but I am trying to avoid the enormous bill I will get for having the dealer fix it. Thanks for helping.

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Comments (8)

larryf
18 years ago
What are the numbers on the engine?

I believe this mower was equipped with a Briggs - but I am not sure if it was the flathead or overhead valve engine.

Most of the primer problems are related to a bad gasket between the air filter housing and the carburetor. The primer bulb is actually a small air pump that sends a shot of air to the carburetor float bowl. Air pressure in the float bowl forces a shot of fuel into the carburetor venturi area.

Since your engine starts on a prime - but does not continue running, I suspect there is an additional problem in the carburetor. Perhaps the main fuel jet is dirty or perhaps there is old fuel in the carburetor from last year.

Try giving the carburetor a little more prime to see if the engine will continue running. If the engine starts, replace the gasket between the carburetor and the air filter housing. Sometimes the plastic air filter housing warps and a gasket does not solve the air leak. Some techs use two gaskets. I usually replace the air filter housing.
baymee
18 years ago
Since your engine starts on a prime - but does not continue running, I suspect there is an additional problem in the carburetor. Perhaps the main fuel jet is dirty or perhaps there is old fuel in the carburetor from last year.

My response as well. Also, varnish in the carb, especially in the main jet of a Tecumseh carb, is the problem.
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jerry880
Original Author
18 years ago
Thank you very much. I just joined this site and it seems there a lot of people willing to help the less mechanically inclined like myself. Thanks again.
bill_kapaun
18 years ago
It appears that is a Briggs engine with the bowl type carb.
Remove the "Brass Nut" that holds the carb bowl on. THAT is your Main Jet. Clean out the hole(s) with a fine wire, like you would find on the tie for a loaf of bread.

You'll probably want to clamp off the fuel line first.
You may also want to "flush" the line for a couple seconds with the bowl off.
paulgill123
17 years ago
I have a John Deere JS63 6.5 engine walk behind lawn mower. It will not start at all and it has been parked in my garage for over 2 years. I was wondering if that has anything to do with it. If someone knows a solution to this problem it would be really helpful. Thanks.
sirwired
17 years ago
Yes, a mower that has been sitting idle for two years almost certainly has a plugged carb. Drain and properly dispose of all the fuel, clean the jet hole built into the "nut", and see if that helps.
lynn_ogard_gmail_com
15 years ago
I just bought a really nice John Deere push mower off Craig's list. The seller started it for me and when I got home I started it and mowed. Here comes the embarrassing part. I forgot what I did and since I can't get it to start. On the handle it has a throttle towards me a turtle and push away a rabbit. Must have a choke and you pull a lever and hold with thehandle when you pull the rope to start. I have pushed lever all the way to rabbit and pulled, then turtle and either way - nothing. I know the mower is good.
I am definitely doing something wrong. Couldn't be that tricky. Any help? Much appreciated
lynn_ogard_gmail_com
15 years ago
I just bought a really nice John Deere push mower off Craig's list. The seller started it for me and when I got home I started it and mowed. Here comes the embarrassing part. I forgot what I did and since I can't get it to start. On the handle it has a throttle towards me a turtle and push away a rabbit. Must have a choke and you pull a lever and hold with thehandle when you pull the rope to start. I have pushed lever all the way to rabbit and pulled, then turtle and either way - nothing. I know the mower is good.
I am definitely doing something wrong. Couldn't be that tricky. Any help? Much appreciated