I have an older (1986) 4250 model that (90% of the time) won’t start after running for a period of time. For example, I can go up in the cab and run the mulcher (15 ‘batwing) for an hour or so and if I turn the tractor off or shift the cutter to high center and turn the engine off, it won’t start immediately. The starter motor cranks the engine but does not start. I have to let the tractor idle for about 45 minutes and then it will start right away. At all other times, ie with a cold engine, it starts perfectly. This has happened to me about 6 or 7 times and it’s frustrating. I have changed all the fuel filters (3) and the problem still exists. It is now winter so this is the best time to fix the problem, but I am not sure if I have a fuel pump problem, injector pump problem or some kind of air blocked fuel line problem that dissipates during that 45 minute period. Any ideas before I damage the fuel system?
Does the engine start as fast as it should when hot? Do you get any smoke from the exhaust when it won’t start? I don’t think you have an air problem. The air would not dissipate on its own. If the engine is starting fast enough, I suspect the pump is getting too weak to push fuel through the injectors when hot. I would not recommend the cold water collation method. That could lead to more damage to the pump. Tight tolerances in the pump could cause parts to seize if the exterior of the pump cools and contracts while the internal plungers are still “hot” and expanded.