JD 445 gas Kawasaki engine fouls the plug on the left cylinder

[beenthere]

Appears, to me, there is just one injection nozzle. It being to inject fuel into the carb, unlike the diesel injector systems.

 

[Richard001]

If you don't have the service manual, there is one here:
http://www.mytractorforum.com/images/reference/JOHNDEERE425445455.pdf

It's large.

Richard

 

[BrianQ]

I stopped by the JD service center and picked up a copy of the mechanic's notes. Comp Test results 230 PSI for both cylinders. He next removed the left side valve cover to check the push rods and they were fine. He replaced the valve cover O ring.Valve clearance was good at .010. Plugs on both sides were soaked with gas and sooted up. So it appears that the fouling is gas not oil.He replaced the injector nozzle with no improvement in running. He then pulled the manual and ran a 30 point test. Test# 16 indicated the grounds to the module were not grounding like they should. He traced the wires and found a splice that might be the problem. Still had a high reading, so he spliced in 3 separate ground wires to fix the problem and found that it ran better. They then checked the fuel pressure(spec 25-27) actual pressure was 30 PSI. They replaced the fuel filter (which I had already done). They had a new fuel injector module and they tried swapping and it did not make any difference. So they moved to replacing the air pressure sensor as it helps control the fuel. They changed out the fuel pressure regulator and the fuel return line and monitored for any noticeable fuel pump problems. They changed out the coolant temperature sensor as well. At this point the engine was running only marginally better. He turned on the key and disconnected the air temp sensor as the manual had indicated that it could be a source of the problem. Once he reconnected the air temp sensor, he started it back up and it ran great! He replaced that secondary harness to the air temp sensor and it was running pretty darn good when I picked it up. It ran strong with no problems until now. It is back to fouling and running rough.

 

[BrianQ]

Appears to be gas fouled.

 

[KYErik]

Wow- that was a real thorough workup by the mechanic. Thanks for posting all of the details.

Does that engine use any type of vacuum operated fuel pressure regulator (like many automobile engines) that increases fuel pressure when vacuum is low? If so, I would investigate that as a possible problem (sticking and making the mixture too rich even when vacuum is low). You said they changed the regulator, but did they put the old one back on?

I would also wonder about the coolant temp sensor and the air temp sensor. You said that they "changed them out"- but did they put your sensors back in after the test? If the coolant temp sensor was relaying info that the engine was very cold- then the computer would richen the mix. Some engine also richen the mix when the engine is running a little too hot. Do you have a temp gauge on the machine? Does it run any smoother when it is cold, lukewarm or full temp?

 

[BrianQ]

They replaced the coolant temp sensor and I just replaced the air temp sensor. It runs better in warm temps. There is a coolant temp gauge and it seems to work fine.
I am not certain about the operation of the fuel pressure system (vacuum or otherwise). To me it seems that a lot of fuel is going into the carb. They replaced the fuel regulator.

 

[buickanddeere]

I am leaning towards an engine with low coolant temp or an engine controller receiving a signal that the coolant temp is low or the airflow is higher than it actually is?

 

[KYErik]

Like buickanddeere I am also leaning toward an issue with coolant temp. You said the coolant temp gauge works ok. How far does the needle come up on the temp gauge?

I may have missed it, but did you replace the air cleaner or check for a mouse or insect nest/other restriction in the air cleaner housing?

 

[BrianQ]

I've replaced the air filter and inspected the housing and intake area; no obvious problems. I'll have to run the motor to see what the temp gauge shows once it warms up.

 

[KYErik]

Did it start running badly all of a sudden in the past few months? Or has it been a gradual process?

If the thermostat is stuck open, or the engine is one the verge of overheating, that could also be the issue.

Does the engine start quickly and run good when cold? It almost sounds as if the engine control unit is keeping the mix rich (as if the engine is cold) even when the engine gets hot and should be running on a leaner mix. Did they unplug your ECU and plug in a replacement? If the coolant temp sensor is working OK, and the wiring is OK and the fuel pressure regulator and injectors are OK, then I would think that swapping in a known good ECU would be the next thing to test.