hchi
Member
I have been working on a friends 200 Merc EFI (Serial Number OF068759). My friend said he can get the boat to start by giving it throttle upon start and prior to getting on plane, he said he had to rev the motor to 3500 rpms in neutral 8-10 times. After that he could get the boat to rev up and get up on plane. The boat is not idling correctly and having a hard time starting. He brought it over and i was thinking the switch boxes or stator and trigger could be bad. It has fresh fuel, did a compression check all six wire about 110 +/- 4, fuel pressure at 35 psi, spark is good in all six cylinders. As i was checking everything out, I disconnected the the 2 brown/black wires on the port side temp sensor and found the TPS sensor was way out of spec. Closed it was at .640 and I adjusted the TPS at .250 when closed. I also checked the manifold temperature sensor. I saw it the impedance move up in down in the shade and hot sun, but have no clue where it should be at. After the TPS was adjusted it fired up and ran smooth with no misfires. He took it strait out to the water and it ran fine. The next morning, same issue, it would not stay started and die about 2-4 seconds after cranking. I'm going to do another check and if the TPS is not holding at .250 when closed, I'm thinking it is bad. The issues is that it is a $600 part now. Another thing i was thinking could it be the ECU? Any thoughts.
