John Deere X750 engine stalling problems.

[JR Hartley]

Hi,

Does anyone have any helpful advice about engine stalling problems on the 3-cylinder diesel engine on a John Deere?

The engine starts and runs perfectly. After about 45 mins of running time, it’s prone to inexplicably dropping its revs and stalling, unless I stop it moving and switch off the cutting deck. Sometime, the revs pick back up, sometimes they don’t and it cuts out. It then re-starts immediately when I crank the engine.

The main dealer thought it was a clogged fuel filter. After a big service (all filters etc) the problem remains.

It seems to be that the engine is being starved of either fuel or air (or both) on an intermittent basis. I can’t work out why. It’s a pretty simple engine compared with a car engine but clearly not as simple as either I (or the main dealer) thought.

Any advice would be welcome!

Thanks.

[5bob]

If I was going to breakdown having been given those symptoms I'd first check the fuel lines from the tank to the filter, quite often bits of grass get in the lines especially if there's any sharp bends or banjo bolts, grass hangs up in them allowing enough fuel through but eventually causing starvation. You could try blowing back down the pipe from the filter back to the tank as long as you don't mind the taste of diesel, obviously any work would mean bleeding the system.

[JR Hartley]

Many thanks for that. I think I’ll have to investigate the whole fuel system, rather than just hoping that the new filter might solve the problem.

As you correctly say, bits of grass get absolutely everywhere!

[HRH2009]

I had a similar problem with a Kubota mower. There were two inline filters which were changed, but the source of the problem was dirt/filth in the fuel tank. I haven't removed the tank yet , but I have had less problems by keeping the fuel tank close to full most of the time.

At the end of the mowing season I shall have to remove the tank and swill out the dirt. Not a straightforward job but unavoidable.

[spikeyhead]

Is there a breather on the fuel tank?

[JR Hartley]

I’ve been trying to find out. There must be one somewhere, but the tank is hard to access and I haven’t yet found anything on-line to direct me.

A clogged breather causing a partial vacuum to build up in the tank after 45 minutes of use might account for the pattern of trouble I’m seeing.

When I use the machine this weekend I could always remove the fuel filler cap once the stalling starts - if it stops happening, then you’re probably correct and I just need to positively identify and unblock the breather pipe.

Thanks for the idea!