1990 40hp Evinrude....Help please

Ok, here is the deal. I took the boat out for the first time 3 weeks ago. Ran kinda rough at first due to sitting all winter. Couldn't get it over 2700 rpm. Shut it down, ran it with out shifting into gear, there was a few surges and bogs then it finally took off. Have had it out 2x since then and can't get it over 2700 rpm. Put sea foam in gas and ran it in the driveway with muffs ran great. Put it in the water and the problem was still there, but only under load. Am getting pretty frustrated, it ran great 30 mph and now 3 weeks later won't even register on speedo. Starts good but idles rough. Thinking about siphoning the old gas out and putting fresh gas in with another can of sea foam. What do you guys think?

Re: 1990 40hp Evinrude....Help please

Did you check your plugs?

Re: 1990 40hp Evinrude....Help please

Checked my plugs and they were both dry and all the wires had good connection.

Re: 1990 40hp Evinrude....Help please

Running well on the muffs only indicates it runs.
Were the plugs the same color?
Try a little choke if it responds then its a fuel problem.

Re: 1990 40hp Evinrude....Help please

steelespike said:

Running well on the muffs only indicates it runs.
Were the plugs the same color?
Try a little choke if it responds then its a fuel problem.

Click to expand...

Plugs both looked the same and appeared to be burning good. I did give it some choke (pushed in the key) while it was running and it just acted like she was going to kill on me so I let off the choke.

Re: 1990 40hp Evinrude....Help please

The guy that had the boat before me said he took off the oil injection and to mix the gas 50:1. Could this be causing the problem if he didn't unhook all the safety (oil injection failure) systems? There is a warning horn listed saying motor won't get past half power if it is overheated. My horn doesn't work so if I am getting this warning I wouldn.t know.

Well, I took the fuel filter off yesterday and it was pretty plugged. I actually tipped it upside down and tapped it ans a good sized pile of crap came out. I purchased a new fuel filter for $7. Not sure if that is the problem but it may be the reason it was starved for fuel. Will get it on the water this week and put it under load to see if it helped. Crossing my fingers!!