Hello!
I just picked up a "new to me" Lazer Z 60" with Kohler EFI engine. This is my first time into the EFI world for mowers so bare with me.
It was only running on one cylinder. Found a coil pack arcing at the boot to the block. I put some heat shrink on the boot and it stopped the arcing. New coils are on the way.
It seemed to run fine at an idle so I took it out for a test run in the yard. Found that it has a significant bog/rich condition under load. You can slowly creep the throttle up and achieve full throttle without the blades on but as soon as it senses a certain load percentage (this is a hunch) it skips a beat and bogs hard and blows some black smoke. You can throttle down and bring the rpm back up slowly and get back to previous rpm but any obscure load and it does the same thing. If you creep the throttle up with the blades on, you can get roughly half throttle before it dives hard.
Fuel pressure was out of spec low by 2 psi so ordered new pump. Running pressure seems low with new pump when looping in pressure gauge to pump outlet but not sure what this spec should be as I cant find any reference in the service manual. I took off the throttle body and intake and ran through the ultrasonic cleaner since the previous owner was also running it without any intake filter.... checked compression, both cylinders at 150 psi. Replaced spark plugs. Hooked the injectors up to a 12v pulse machine and also ran them through the ultra sonic cleaner while pulsing to clear them out of any deposits. reassembled everything with new fuel filter, checked all fuel lines were clear and lift pump was working properly. Had to rebuild the starter so the grounds and power supply were checked, cleaned and reinstalled. Once the intake was put back together with air filters, I did an ECU reset and TPS relearn to the best of my ability and still the bog persists...
I have yet to check the O2 sensor for proper functionality but the check engine light is not on. I have verified the CEL does work properly. Although I am curious, when I unplug the O2 sensor, it does not seem to affect the condition of the engine while running. Nothing changes and no CEL so I am assuming it does not continuously check the sensor signal, rather, the heater circuit within the sensor? Makes me question if the O2 sensor is bad but not bad enough to trip a CEL or code.
Any help would be appreciated.
I just picked up a "new to me" Lazer Z 60" with Kohler EFI engine. This is my first time into the EFI world for mowers so bare with me.
It was only running on one cylinder. Found a coil pack arcing at the boot to the block. I put some heat shrink on the boot and it stopped the arcing. New coils are on the way.
It seemed to run fine at an idle so I took it out for a test run in the yard. Found that it has a significant bog/rich condition under load. You can slowly creep the throttle up and achieve full throttle without the blades on but as soon as it senses a certain load percentage (this is a hunch) it skips a beat and bogs hard and blows some black smoke. You can throttle down and bring the rpm back up slowly and get back to previous rpm but any obscure load and it does the same thing. If you creep the throttle up with the blades on, you can get roughly half throttle before it dives hard.
Fuel pressure was out of spec low by 2 psi so ordered new pump. Running pressure seems low with new pump when looping in pressure gauge to pump outlet but not sure what this spec should be as I cant find any reference in the service manual. I took off the throttle body and intake and ran through the ultrasonic cleaner since the previous owner was also running it without any intake filter.... checked compression, both cylinders at 150 psi. Replaced spark plugs. Hooked the injectors up to a 12v pulse machine and also ran them through the ultra sonic cleaner while pulsing to clear them out of any deposits. reassembled everything with new fuel filter, checked all fuel lines were clear and lift pump was working properly. Had to rebuild the starter so the grounds and power supply were checked, cleaned and reinstalled. Once the intake was put back together with air filters, I did an ECU reset and TPS relearn to the best of my ability and still the bog persists...
I have yet to check the O2 sensor for proper functionality but the check engine light is not on. I have verified the CEL does work properly. Although I am curious, when I unplug the O2 sensor, it does not seem to affect the condition of the engine while running. Nothing changes and no CEL so I am assuming it does not continuously check the sensor signal, rather, the heater circuit within the sensor? Makes me question if the O2 sensor is bad but not bad enough to trip a CEL or code.
Any help would be appreciated.
