2005 90 hp johnson overheat alarm

[bart-boat]

my 2005 90 hp overheat alarm came on and now sometimes I get spark to start it and sometimes it sparks about 2 and stops. first thing in the day I can get it to start right up and run for 15-20 minutes and refire , but then it wont start. I have my timing light hooked to it and it (most of the time) gets spark for 2-3 seconds then spark goes away. when I turn on key even first thing the water temp light stays on. when I ran it for 15-20 minutes this morning ,I checked temp at head with heat gun. after warm it stays 140f-155f. is there something that would cut out the spark, such as overheat alarm? sensors ?

 

[oldboat1]

Bad regulator might be a factor. Need full/constant water circulation -- not sure running on muffs would be sufficient. Is charging or tach operation affected?

Did you change out the impeller? Up around 150-155F is pretty warm. If memory serves, the SLOW mode kicks in up around 155 or so(?)

 

[jakedaawg]

Model?

 

[bart-boat]

model j90plsdm, that temp is right by spark plug on the head 155f at worst for a moment , stays around 140f consistent . near thermostat is around 120f. would that cause it to lose spark altogether? thanks for response. bart

 

[bart-boat]

don't believe charging or tach is affected

 

[oldboat1]

should explain "overheat alarm came on". If you overheated, likely cause is water pump failure (needs to be addressed).

A bad regulator could give wonky ignition issues, but should check (measure) spark with an adjustable open-air tester -- see whether in fact you have a spark issue.