Cranks but won't start.

msaeger

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May 15, 2011
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Hi,

I have a John Deere GX75 I can not get running this year and I need to mow :)

Here's what has occurred so far:

I put in gas, set the throttle lever to choke, turned the key, I then shifted to 3rd gear and drove out of the garage. Then I stopped was going to engage the blade and it died. Now when I try and start it the starter turns the engine with no problem but it will not start.

Here what I checked so far:

I pulled the fuel line off the carb and verified I get gas out.
I opened the bleeder screw on the float bowl and I get gas out of there.
I took the air cleaner cover and filter off so I can see in the carb I can see the throttle plate move and close when I set the choke.
I tried spraying starting fluid into the carb and turning it over I got no firing just the engine turning.

I am suspicious of a safety switch because I have had trouble with the seat switch and with that one the engine would turn but not start so I have been trying to bypass some of the switches but am still not getting it to start. The starter will always turn over but it won't fire.

I found a scan of the schematic on google can someone smarter than me tell me what I can do to just bypass all the switches so I can see if on of them is indeed the issue.

View attachment GX75 schematic.pdf

Also tell me if I am just on the wrong track and there is something else I should check.
 

msaeger

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I got a ignition tester and am seeing a spark with the tester when I crank the engine. So how is this thing not starting? I also took off the float bowl and the float moves. Even with a fuel delivery problem I would think it would fire if I spray starting fluid in there.
 

mechanic mark

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Safety switches are there for a reason, Safety for yourself & equipment. I do not recommend bypassing switches. I would start by testing seat switch with a multimeter tool & replacing switch if it's bad as well as other safety switches. You can google testing seat switch & watch utube video.
 

msaeger

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Safety switches are there for a reason, Safety for yourself & equipment. I do not recommend bypassing switches. I would start by testing seat switch with a multimeter tool & replacing switch if it's bad as well as other safety switches. You can google testing seat switch & watch utube video.

If there was a problem with one of them not working would I expect to see spark and the starter motor crank the engine? I was expecting to not see a spark with the tester otherwise how are they preventing the engine from starting?
 

msaeger

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I got it to start! Embarrassed to say what the problem was but it ended up being a fouled spark plug. I decided to pull the plug and test it by cranking the engine and watching for a spark. There was a very faint spark and the plug was coated with something so I sprayed it off with starting fluid after that I got a good spark. Then I put the plug back in and the mower started and I was able to move my much too long grass.

I was too focused on the switches and stressed over the long grass so I missed a simple thing but at least it's working.

Next year I need to start it as soon as the snow is gone before I really need to mow.
 
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