Yamaha mariner efi F70 A

[greenlandtraveller]

Hello all Yamaha enthusiasts sorry for the long text, I really hope someone can help me, as I am far north with limited opportunities, and need advise to get me going again, my engines is Yamaha f70 A
Thanks for letting me join your forum
I have some problems with my outboard engines
I fuelled my drop tanks with fresh fuel, and after refueling my inboard tanks, it seems the problem started occurring,, obviously its tempting to assume that the fuel is the problem, but since I'm in an area, where just getting new fuel is not an option so I want to eliminate all posinilities and drain my drop tanks for water and get my engines running
Here are my observations,
my engines will run fine for the first 10 - 15 min at max rpm,, it will then stall and lower the rpm to around 2000 - 2500
Then most times die, or simply go to idlev, though I am in WOT position. though sometimes I can maintain the lower rpm, but I will never be able to push it back up to max rpm
Oncce I shut off ignition,, and turn on again The whole thing repeat itself. , but with about 5 minutes of max rpm, no trouble
If I do not go to max rpm, there are no problems..... It seems
My tasks here require me to go max rpm, so not doing it is not an option


My thoughts

problems with fuel?



Maybe Vacuum, or pressure hose leaks, close to injectors??


sensor measures bad exhaust values, and lowers fuel inlet? Once ignition is off, it resets itself, and history repeats??

Water IS drained out of fuel, my water separator indicators, shows all good

Sparkplugs, cables and filters are clean and good



Unfortunately these boats are equipped with the lowest level instruments and warning systems, and my screens, shows no alarms,
Please help

[panasonic]

Do you have portable 5 gallon tanks?? If so... run off them and see if the problem is there still.

[fairdeal]

The ECM will 'deliberately' limit rpms for only two reasons -
over temperature, or low oil pressure -

in which case, engine will not run above 2600 rpm
(and it will 'reset' with key off)

BUT - in either case,
despite not having a gauge or warning indicators,
you would still get the audible warning alarm.

You can check that the audible alarm is working:
pull the safety lanyard, then try to start the engine -
while the starter is cranking the engine the alarm should be sounding.

If the horn works,
then your running issue is not an 'alarm condition'