[ChrisBressler]

Does any one out there know what signal the ECM uses to control the on /off of the HP fuel pump. I have a problem in that the motor dies and may not restart for a period of time. The HP pump has been replaced and it still fails. If you monitor the negative side of the pump we have Zero volts when the pump is running and when it fails the voltage goes to 12v. What input to the ECM tells it to turn the pump on or off? This is a 2002 f115. The SECOR book that I have says nothing about this and the schematic is just a block diagram.
Any help would be appreciated.

Chris

[rodbolt]

if your testing from the engine block to the blue wire (ground) side of the pump your getting the expected readings.
measure between the hot side of the pump and the low side.
anytime the key is on the pump has 12V supplied,I think its red/yellow.
the blue wire is the ground path for the pump run and is controled by the ECU.
at key on the pump will run 3-5 seconds.
after that the ECU is looking for either a start signal on the brown wire or an engine running signal from a pulser coil.
if it gets neither or the engine running signal isnt there the ECU removes the pump ground path and the pump quits.
carefully watch the fuel rail pressure just before it dies.
if its a pump shutdown you will see the rail pressure falling rapidly just before shutdown.
if it does not then keep looking.
but the pump can be manully triggered,back probe the pump connector on the ground side and take it to engine ground with a jumper lead.
now the pump will run reguardless of ECU signals as long as the main relay is on.
the 115 is one of the few we occasionally see ECU failures with.
but also check the ISC valve use of the dignostic test lamp may help.
the laptop really wont give much information on that ECU.
but think of the circuit and what your measuring.
with one lead on the pump ground side and the other on the engine block and the pump is running your measuring the electrical "pressure" difference between the pump connector and ground.
as the ecu has the other end grounded you wont see any pressure difference hence a 0 voltage reading.
if for any reason the engine stalls the ECU now removes the ground path and as the 12V supply on the other pin is still there your now reading the difference, through the pump motor windings, to ground wich should be battery voltage at that point.
but the next step is to observe the fuel rail pressure at the point of shutdown and when it wont restart.

[hobohro]

I want to, belatedly, thank for your reply last year. The boat has been in storage for the winter and the problem forgotten during those months. I intend to troubleshoot this again within the next few weeks. I will monitor the 'start signal and the pulser' to see if either go away when the ground is lifted by the ECU. And I found the Yamaha Shop Manuals finally and bought them. They will be a great help in shooting this bug! I HATE paddles!

btw...the engine is really a 2003 f115tlrb not 2002

[hobohro]

but also check the ISC valve use of the dignostic test lamp may help.

What is the ISC valve ?

hobohro

Never mind ISC=Idle Speed Control Valve

[rodbolt]

yep
ISC= IAC to the rest of the world.

[hobohro]

I replaced the ECU yesterday and now the boat runs great. About a month ago
I bought the YDIS software and it will be a great help in maintaining the boat in the future. The YDIS did help with this BUG, in that when the engine was failing I could not turn on the HPFP in the standalone mode, but all other tests would run. When the ECU was working correctly the YDIS would turn on the HPFP at will.

Thanks for all the help!

Kirk