John Deer 304 and 390 series mower trouble

I'm new. Please Help! We have 2 JD mowers that have the same problem. 304 and 390. They start fine, run/mow for a while then just shut down and take a few minutes before they start again. We've replaced batteries, gas, filters, coils, fuel pumps, and cussed a lot. Even had JD service done on them. Still the same problem. I think it's some relay switch but don't know which one to look for. Our JD tractor had the same problem, and we fixed it with 2 relay switches (recommended by a mechanic, don't remember what they are called). I would take them to the JD mechanic, but they are REAL busy and we wouldn't be able to mow the yard for months.

candycar said:

They start fine, run/mow for a while then just shut down and take a few minutes before they start again.

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Typically, this is a clogged fuel tank outlet. Trash in the tank.

Could be internally deteriorated fuel lines from tank to carb. Clogged fuel filter. Inline shutoff valve possibly not letting fuel by.

Someone using an open top spout fuel can. Passing trash from the can to the mower tank. Tank on to carb. Water, bugs, dirt dobbers, grass and so on.

Pull the fuel line AT the carb inlet. Drain into a glass jar. Should be a solid flow from tank. Look for water.

candycar said:

and cussed a lot.

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Starting to like this guy...... LOL

Wonder if a relay is making poor contact but when bounced around the yard either makes good contact or a poor one???? Not sure of this relay you speak of.

Most of the time, safety switches are either on or off.

Thanks Slomo, I'll look into pulling the fuel lines & cleaning the block & fins. Maybe drain the fuel tank too. Yay! more busted knuckles -..- can't wait.

candycar said:

Thanks Slomo, I'll look into pulling the fuel lines & cleaning the block & fins. Maybe drain the fuel tank too. Yay! more busted knuckles -..- can't wait.

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Also be sure to blow through fuel to fuel tank with cap off to remove any debris caught in the line or connections.

Tiger Small Engine said:

Also be sure to blow through fuel to fuel tank with cap off to remove any debris caught in the line or connections.

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Was hoping he would replace them but sure, test what you have.

The last thing people want to deal with is the fuel tank in these. I see garbage from dirty fuel cans more often than I like. It doesn't take much to block a fuel line outlet in the tank. You can blow them clear with air, but the trash will keep repeating the problem.

Of course, the tank on these is in the worst possible area that engineers could dream up. The entire upper platform has to come off the get the tank out of one of these.

There is no easy way to clean the tank, if that is what has happened to these mowers,