1978 evinrude 85 hp question please help

[antonio88]

hi everyone i hope someone can help me here, so i took my boat yesterday to the lake it was running fine like always but then i just stop in the middle of the lake to get into the water w my family and afther like 20 min we decited to go back to eat well is where the problem started i mean the boat just wouldnt go faster than 20 miles on WOT it runed but wasnt performing like allways this is the first time the motor is doing this. so this morning i checked compression and still have the same as the last year, i have spark and im getting fuel, i fired it up w the water hose and is idling perfect like nothing is wrong with it, any advise to check

 

[emdsapmgr]

Check for spark on all 4 plugs. Possible it is not firing on all 4 once it's warmed up.

 

[antonio88]

I have spark on all 4 when is cold so how should I check when is Warm I should let run for a while with the water hose and then check it again?

 

[Bosunsmate]

I have spark on all 4 when is cold so how should I check when is Warm I should let run for a while with the water hose and then check it again?

yes, they often get hotter at idle than at wot

 

[emdsapmgr]

That's correct. That engine will heat up to it's warmest temps when running at idle. Cyl head temps will run between 143 and 155 at idle, so warm it up fully prior to the spark test.

 

[antonio88]

Thanks guys I'll check that, yes my motor runs around 135 and 145 at idle, I'll let y'all know if I have more issues with it!!!!!!!!