Mariner 75HP Opitmax alarm

[Bigrhys]

Hi ,

Ivan here from Ireland,
My 2008 Mariner 75HP Optimax has starting to alarm @ 3800RPM, when I easy back the alarm clear ans it runs fine until 3800
Voltage shows 14.1 to 14.2 Volts
Temp sits around 95F and dropped to 85 when revved, so cooling fine.
I stripped the vaporizer and cleaned all fine


Any Help would be great

Ivan

[boats.net]

A continuous alarm could be overheat, overrev, low oil, oil pump failure, or sensor signal out of range.
Need to have it checked with computer diagnostic to see what fault code is activating alarm.

[Bigrhys]

Hi All

A continuous alarm could be overheat, overrev, low oil, oil pump failure, or sensor signal out of range.
Need to have it checked with computer diagnostic to see what fault code is activating alarm.

Here is my reasoningOverheat , I think it is not a temp issue because it running between 85 and 95 F
What temp should it run @ ?
Over rev, it is alarming @ approx 3800 this should be well inside rev limit
Low oil, the tank is full, if the tank was low or a faulty sensor the alarm should come on once the engine is started and not effected by the 3800 RPM

Oil pump failure ; not sure how to check
sensor signal, ; again not sure how to check, do any body know of some likley offenders , or can I plug out certain sensor to try and trouble shoot,

I do not have any mariner diagnostic ,but I am a competent engineer,

Thanks again for all your help

Ivan Ireland

[boats.net]

Unfortunately without a computure diagnostic you will have to start testing all the sensors. You will require a service manual, the following link should assist you.

889785R01 - SERVICE MANUAL, 90/115, 3-Cylinder DFI $77.30

[Bigrhys]

Cheers,

I removed the termostat cover and found some weed keep the pressure relief valve open, not sure but I think that is it fuction, just rebuilding the engine and going to try,

Cheers

Ivan

[Bigrhys]

Help Help in Ireland

Hi
Can anybody tell me if there is a neutral switch on the engine, the reason is because when i use the hand fast idle the alarm also come on a 3800+
My thinking is that the engine thinks it is in neutral and therefore is governing my revs as a safety factor, if the switch is sticking and I am in gear it may also think I am in neutral and govern my revs

Any Thoughts ?

[Bigrhys]

Problem sorted,

Neutral switch, stuck in therefore engine behaving like it was neutral.

Happy man