I bought a ZD21 about a year ago and have a lot of troubles with it starting. It needed a new starter and Battery and I have replaced both of them. The mower seems to not want to start with the throttle at an idle, but it will Start with the throttle turned up to full throttle. Battery voltage at the starter while cranking is 8-9 Volts. I have verified that the fuel shutoff solenoid is not sticking. I have verified that the fuel pump is pumping with the key in the on position. I have checked the resistance on the glow plugs and they are at about 1 ohm. With the temperature at 72 deg F this evening, the mower wouldn't start without turning on the glow plugs for 15 seconds and even then it died with the throttle at an idle and had to be started with the throttle turned up. The mower has less than 1000 Hrs and was previously owned by a homeowner. Thanks in Advance.
ZD21 Starts Hard
- Thread starter Woodsguy
- Start date
Captain13
Active member
Equipment
M7040 4WD ROPS, ZD28, Woods (84” box blade, 72” harrow, 48” pallet forks)
When my ZD21 had that problem, it was the fuel shutoff valve. I could turn the key on and the shutoff would not “click” until the throttle was pushed to about half throttle. Then it would start. One day, it wouldn’t shut down. I replaced the fuel shutoff and since then it starts and stops like it’s supposed to.
Fuel shutoff solenoid may be failing, or there's possibility that the shutoff arm assembly may be sticking. Pull the solenoid off and see if the arm it actuates is free. If it is, replace the shutoff solenoid.
So my understanding on this is that the fuel shutoff solenoid actuates when the key is turned to the off position and the solenoid stays on for 10 seconds and then power to the solenoid is turned off and the fuel valve returns to the open position. I did a visual inspection on the solenoid and it seems to be doing what it is supposed to do. After about 10 seconds in the key off position, the solenoid returns to the former position and seems to move freely. I don't know for sure that the internal valve is working or not.
I wanted to post an update on this thread in case someone in the future is reading this. I was getting around 8 volts at the starter from hot to ground at the starter while cranking. I did a voltage drop test on the battery cables and the negative cable was dropping 2.6 volts while cranking. Wow! I plan on ordering and installing a new cable and seeing if that was the whole problem. Thanks everyone for the input!
Captain13
Active member
Equipment
M7040 4WD ROPS, ZD28, Woods (84” box blade, 72” harrow, 48” pallet forks)
If you haven’t ordered the cable, NAPA stores usually carries cables in stock. Take your old one in so you get the right length. The ones I ve bought there are well made cables and much cheaper than OEM.