1987 merc 90 HP full throttle issue

[ctrevis7]

I ran my boat early this morning on my way to go hunt and it started cutting back a little. On the way back to the ramp I could only get about 5mph at full throttle! Any suggestions?? Maybe a spark plug issue? Thanks in advance!

 

[quicktach]

Re: 1987 merc 90 HP full throttle issue

Could be lots of causes. Check for fuel starvation .... gas tank venting OK? Any filters - engine or water filters plugging up ? Has anyone been working on motor ? More detail needed. Happened before ? Could be electrical too ....what is S/N of engine?

 

[CharlieB]

Re: 1987 merc 90 HP full throttle issue

Weak spark?

Start with basic troubleshooting

Inspect spark plugs
Compression test
Spark test
DVA test ignition stator
Test fuel pump/flow cranking
Fuel filters
Clean carb

 

[Chris1956]

Re: 1987 merc 90 HP full throttle issue

I recommend you perform the top three items on Charlie's list and post back.