Kubota M4950 won't start

Robert Largent · New User Joined: 13 Mar 2009 Posts: 1 Report to Moderator

My Kubota M4950 won't start we have replace the fuel injectors and glow plugs. Tractor trys but won't go we think is might be the injectors pump. Does any one have any ideas. Thanks

Jerry/MT · Posted: Fri Mar 13, 2009 10:58 am Post subject: Re: Kubota M4950 won't start

Diesels are really pretty simple. They need fuel to the cylinders, compression in the cylinders and a good starter and battery too spin the engine over. In cold weather they need a starting aid and the best one, in my opinion (if you have an electrical onnection) is a block heater.
Having said that,make sure that you have fuel through the filter(s)to the injector pump. Filters get dirty, wax up in really cold weather,and collect water. Fuel lines loosen from vibration and let air in suspect and don"t allow the injector pump to prime. The screen on the fuel tank valve gets clogged with crap and corruption, algae, etc.
So when is the last time you changed the fuel filter(s)? Open the tank valve and open the bleeder on the filter farthest from the tank. Are you getting a lot of flow? If not something is restrictinting it, either the filter(s) or the tank valve screen. Now open the line closest to the tank an see if it has plenty of fuel flowing. If it doesn"t the tank outlet is clogged. Drain the tank and clean it. If it does, the filters are clogged. replace them. If you have plenty of flow at the filter nearest the pump,then look for loose fittings or cracked lines, something letting air into the system. When you think you have everything tight and leak free, bleed the injectors by loosening the fitting on the injecttor and cranking til you have all fuel and no air coming out of the injector lines.( Make sure you start this process with a fully charged battery.) I do this one injector at a time, other folks do all at once. It doesn"t matter, just do it. Your tractor should start. If it doen"t, you either don"t have all the air out, your starting aid is not working, your pump may be bad, or your engine compression is too low (worn out rings or bad valves).
Also make sure that your air filters are not clogged "cuz you have to have air and fuel.

Tx Jim · Posted: Sat Mar 14, 2009 3:14 am Post subject: Re: Kubota M4950 won't start

Robert,
I have a M4900 and it wouldn't start a while back. I thought I had run it out of fuel as fuel gauge doesn't work. I put fuel in it but couldn't get fuel to inj. pump. I found out there's a "tiny screen" in fuel cut-off valve that has a clear bowl on bottom with a filter & screen was plugged.