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Have been messing with this unit all summer. Bought it from a guy that knew he was having issues but wanted a bigger unit. I bought his head ache. I installed the unit on a pontoon following a wiring schematic for 1996-01 DT144 and DT140 units. #1 and #2 cylinders have issues. I can pull the plug wires on 1 and 2 with very little change in engine rpm. 3 and 4 both significantly change with 4 causing so much the unit dies. It appears that the unit is only running on 3 and 4. 4 being the strongest cylinder. Compression after 8 revolutions are 1 105, 2 100, 3 100 and 4 100. 15 second spin on each is 1 105, 2 100, 3 103 and 4 105. Very little change in compression with longer test times. Low pressure fuel pump was removed and found it is fine. Valves were in perfect condition. It pumps significant fuel when spinning the unit over. I have 38lbs of fuel pressure when running and falls off at a very slow rate. It holds very well. I have no alarms or codes that flash on the monitor gauge. The coils, plugs, injectors, atmosphere and air temp and gear count sensors along with the ecu have been changed. It appears that the 1 and 2 injectors receive the same voltage as cylinder 4. Not sure where to go next. Any direction would be appriciated
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VIN # is 11503-971628 -
I would pull the plugs, and verify you are getting good/equal fire at each plug first. If not equal fire, investigate why. If plugs all have strong/equal spark, then I'd probably swap #4 & #1 injector, and #3 with #2 injector, and see if there's any difference. If the motor runs the same, strongest on cyls 3 & 4, then I might inspect the reed valves?
It is important that all the parts you replaced (coils, plugs, injectors, atmosphere and air temp and gear count sensors) tested good by the service manual.
If you have no spark on 2 cyls, is the motor in safe-mode? Wiring problem, or might be heat sensor, oil flow switch, neutral switch? Before you switched these parts, was the motor running the same way, did motor run differently?
Just a few thoughts.
Good luck, post back on what you find out.
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