I bought a 2006 Komatsu FG25T-16. It has been sitting for several months. It has an LP K21 engine. After the forklift sets for a few minutes with the fuel on, it starts right up, runs great for 10 seconds thens starts to run rough like it is lacking fuel or over fueling. If you start it right back up it will start rough and run rough. Let it set for a few minutes, starts right up again smooth then goes rough. The check engine light is on all the time while this is going on. It seems to me like the fuel builds pressure while it is setting then as it uses it,'it can't keep up with demand. If you work the throttle a bit you can finally get it to run semi smooth at higher RPMs but it still isn't right. What could be causing this? Thanks for any and all help. I am 200 miles from a dealer
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The Stateside K-21/25 Komatsus do not have distributor ignition systems. Over here they are all "Coil On Plug".
How many hours on this truck?
The fact that the Malfunction Indicator Lamp is on means there is more to it than simply not getting fuel out of the regulator.
Worn spark plugs in these engines can cause some weird codes to pop up.
There is an accelerator pedal "tap dance" procedure you can do to initiate a "blink codes" way of finding out if any Diagnostic Trouble Codes are stored in the ECM.
You can search through the Komatsu archives in this forum and find instructions on how to do the pedal dance.
But beware, if the accelerator pedal position sensor is defective, you will be unable to get the blink codes process to happen.
The darn pedal dance itself is a bit tricky to do for the first couple of times you try it. But if you keep trying and trying and still can't get it to set up the blink codes display with the MIL, the APP Sensor is probably defective too.
You may end up having to call a dealer with a diagnostic reader to find out what's the problem.
I would be tempted to check the distributor cap. Maybe it needs cleaning out or replacing. Make sure theres no white furry stuff on the contacts, or condensation Inside. Also check the spark plugs. Let me know how u get on
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