JD 445 back to driving me crazy!!! Short trip too. LOL

JD Seller

Well-known Member
I have a JD 445. It is driving me nuts. It started running erratically. Would not speed up with the throttle control. Seemed like it would flood out and die. Then it would start real hard. Cranking along time before it would start. So I have done the following:

1) Changed the inline fuel filter. Also replaced both spark plugs just to rule out one of them breaking down with heat.
2) Checked the fuel pressure and flow at the inlet side of the throttle body. Both where in spec.
3) Found out the fuel pressure regulator had a small hole in the diaphragm that allowed fuel to be pulled into the engine making it run rich. Replaced the regulator with a new one.

At this stage I thought I had it fixed. It started and ran fine the night I replaced the regulator. It had warmed up to operating temperature while I was working on it. The next day I went to start it cold and it started hard again. It did start after cranking for 30 second or so. It would only run at an idle. It would not take throttle. I let it run for 3-5 minutes and then you could slowly give it throttle. Once up at high idle speed it will run there. Seems to have power but is not snappy like normal.

During all of this there are no codes being flashed on the dash.

So I just mowed the yard a few times with it this way. Another fellow called wanting me to service his mower and level the deck. His mower is a JD 445 just a few years older than mine.

Yesterday I had both of them in the shop. His runs fine, mine still starts hard and will hesitate when given throttle.

So I did some switching of sensors. To try and locate my problem.

1) Switched the air temperature sensor and nothing changed.
2) Switched the Mass air flow sensor and nothing changed.
3) Went to switch the water temperature sensor and found a broken wire in the harness. It only had a few strands left holding. I repaired the wire. The mower seemed to run fine and would take throttle. Problems solved!!! NOOOOOOO as soon as the engine cooled down again it went back to not taking throttle. It does start better now. Still not quite right but better.

I had more time today.
1) Check the resistance at the water sensor and voltage supplied to it. Mine is the same as the one that runs right. Showed me the harness is not the issue at the water sensor. Making sure my harness repair was good.
2) Switched the injection control module. (I was sweating on this as it is $1100 new) Still no change.

So I have switched everything but the injector itself. I can see the pattern it is spraying and they "look" the same.

I am also wondering if it could be a ignition/spark issue not fuel???? I have change the plugs twice just for fun.

Any ideas????
 
My chore pickup will do the exact same thing if I am at the bottom of the gas barrel. Nothing else seems to know the difference, but that thing can tell. What is the fuel like? Sounds like it is struggling to get it to fire until the engine is heated up enough.
 

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