My zd 331 is running very rough at idle and has a lack of power when getting into a little thicker grass. A little history, the machine has apprx 3000 hrs. Last year it overheated and the head was cracked, the head has been replaced and the tractor finished last years season. This spring I really noticed the rough idle and lack of power. When not under load and giving it some throttle the engine smoothens out considerably but still seems a little off. Is there some simple old school ways to determine if I have a compression problem. I don't really want to go out and buy a diesel compression tester or a leakdown kit. The engine does not appear to be using or burning oil out the exhaust. My Kubota tech said it sounded like a fuel delivery problem. So far I have changed the inner and outer air filters, changed both fuel filters, I pulled of the fuel tank selector valve off and noticed the o rings were damaged, I will be installing a new one tommorow. I used compressed air to blow the fuel lines starting from the fuel selector valve towards the fuel tanks, the diesel in the tanks bubbled noticeably, I also blew the line from the fuel filters toward the selector valve. Is this good enough or should the lines be cleared out more thoroughly by using some kind of wire to "snake" out the lines. The fuel pump sounds when I turn the key, I have a new one in stock which I may put on if nothing else seems to help. With engine running I slightly opened the nut on each injector and see some fuel, when I tighten each one I can here the engine come back up, so there does seem to be fuel getting to each cylinder but maybe not enough. Sorry about being so long winded by I am at a loss, any advice would be greatly appreciated. Thank you!
ZD331 rough idle, lack of power
- Thread starter grownmow
- Start date
I like to look at the simple (free) things first. Since you were looking to fuel-lines; there should be a return line from one of the injectors to the tank, if that one gets boogered up it can cause problems, clean/replace that. You had the head done last year, it may be time to readjust valve lash.
Just an obervation on the way you blew out the fuel line back to the tank.
If there was any foreign matter in the line you would now have blown it back to the tank where it can flow back and block the line again.Its much better to drain the tank and make sure it clean from there all the way back to the pump.
Dave
If there was any foreign matter in the line you would now have blown it back to the tank where it can flow back and block the line again.Its much better to drain the tank and make sure it clean from there all the way back to the pump.
Dave
Thanks for the helpful advice "birddogger" and "B7100". I have not had a chance to get back to that machine as it has become a little hectic and I had to wait for the parts to come in. What is the backlash clearance on this ZD331, 31hp 3 cylinder engine, I don't think I will find this valve adjustment procedure in my operator's manual. Is there any special steps when doing this, example: the engine should be warmed up before adjustments made. I will be getting back to this machine monday or tuesday. I will continue to keep this post updated with my progress.
Finally got back to the zd331. Put on the new fuel pump, no improvement. I'm going to take the injectors off and bring them in to be tested, just to rule that out. If their ok i will be doing a compression test. As I said earlier the engine severely overheated to the point it cracked the head and wasted the radiator. Because it got that hot the rings may not be doing their job as well as they should. I'll continue to give updates of my progress.
Going back to the running hot issue. Why did it run hot? Was the radiator clooged with grass/dust, or did the thermostat stick? Usually if you run something hot enough to crack a head you'll have issues with pistons scoring and low compression . You may want to rent a compression tester...
Your right on the money WayneJessie, did a compression test and one of the cylinders is down 100psi compared to the other 2. Motor is coming out tommorrow, hopefully the cylinder will not be damaged. I will let you know what I find. Thanks.
I have the same model Mower. Mine has also been running rough lately. A couple weeks back I started some maintenence and have changed outter air filter and oil and filter. It was running OK for a bit although today it started to splutter and then just shut down? Does anyone know if this could this be from a fuel blockage? I have removed both fuel filters and will replace as a first step. It was running quite hot at the time (not in the red ) Any other advice??