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2000, HPDI, 200HP, 535 Hours. Just completed a rebuild due to low compression on cylinder #5 due to a head gasket failure. Had block bored and honed. Used complete genuine Yamaha gasket kit, etc. Compression is 120 on all cylinders now. ALL fuel filters are new. High pressure pump was sent out last year for service.
Symptoms: rough idle, slow throttle response, misfire/backfire, puff of blue smoke emits from exhaust in sync with misfire. I did not have these symptoms prior to the rebuild. Engine is being run in a test tank in gear using the harness, oil tank, ignition switch, gauges etc. from my boat.
Confirmed running spark on all 6 cylinders. When I pulled the injector connectors on cylinders 1,2 & 3, there is no change in the poor running condition. When I pulled 4,5 & 6, the engine stalled. When I pulled the spark plug boots I had the same results on the same cylinders. No codes on Yamaha Diagnostic software until I disconnected the injectors. Also, the injectors passed the stationary test using the YDS. I pulled the injectors anyway and sent a dose of Seafoam thru them in both directions even though they were sent out for service a year ago. Reinstalled, same results.
Update 12/24 :Forgot to add this - Had white smoke shortly after first startup. Found the upper LPFP was leaking (only had approx. 20 hours on it prior to rebuild). Replaced it with a new one.
Update 12/28: Confirmed: spark plug boots, coils, pulser coil, o2 sensor, injectors, tps (set to 61) all ohm to spec. Swapped injector 2 with 5. Same result running result. Now injector 2 is working in cylinder 5 and injector 5 is not working in cylinder 2. Still no change in running condition when I unplug injectors 1,2 or 3. No corrosion on any connection or grounds. Injector Driver???
Update 12/29: Removed injector driver, opened up just to take a look. Looks like new inside. No idea how to check it. Holy s*** they are expensive. Trying to borrow one to see if it's the issue. Any input would be GREATLY appreciated.
Symptoms: rough idle, slow throttle response, misfire/backfire, puff of blue smoke emits from exhaust in sync with misfire. I did not have these symptoms prior to the rebuild. Engine is being run in a test tank in gear using the harness, oil tank, ignition switch, gauges etc. from my boat.
Confirmed running spark on all 6 cylinders. When I pulled the injector connectors on cylinders 1,2 & 3, there is no change in the poor running condition. When I pulled 4,5 & 6, the engine stalled. When I pulled the spark plug boots I had the same results on the same cylinders. No codes on Yamaha Diagnostic software until I disconnected the injectors. Also, the injectors passed the stationary test using the YDS. I pulled the injectors anyway and sent a dose of Seafoam thru them in both directions even though they were sent out for service a year ago. Reinstalled, same results.
Update 12/24 :Forgot to add this - Had white smoke shortly after first startup. Found the upper LPFP was leaking (only had approx. 20 hours on it prior to rebuild). Replaced it with a new one.
Update 12/28: Confirmed: spark plug boots, coils, pulser coil, o2 sensor, injectors, tps (set to 61) all ohm to spec. Swapped injector 2 with 5. Same result running result. Now injector 2 is working in cylinder 5 and injector 5 is not working in cylinder 2. Still no change in running condition when I unplug injectors 1,2 or 3. No corrosion on any connection or grounds. Injector Driver???
Update 12/29: Removed injector driver, opened up just to take a look. Looks like new inside. No idea how to check it. Holy s*** they are expensive. Trying to borrow one to see if it's the issue. Any input would be GREATLY appreciated.
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