Evinrude won't REV up!!!

[decoy033]

Once again I am asking for help For this 1973 135HP. OK here's the story.... When I have the boat in water an it is in gear at full throttle the boat goes only about 10 MPH @ 1900 RPM. The carbs open up all the way. And then if I put it in neutral and use the warm up lever the RPM goes up all the way where it should at 5000 - 5500 RPM. Also in reverse the RPM goes up. But foward top speed is about 10MPH. I have this motor on a small light 16FT boat. What is wrong? I have a SS prop on it I think it is 12&3/4 inch 19 or 21 pitch? Is this too much prop for this motor? Please let me know. Thank you for your time.

 

[Walker]

Re: Evinrude won't REV up!!!

Start with the basics. Compression test, spark test and carburators. If you have good compression and are getting good spark to all 4 cylinders at the right time, then you have a fuel deliver problem. It would be a good start then to tear the carbs down, soak them in carb cleaner for a couple of hours, blow them out with compressed air and visualize that they are sparkling clean paying particula attention to the jets, passageways and orifices. The main jets are in the barb bowls.

 

[decoy033]

Re: Evinrude won't REV up!!!

Yes, The carbs have been cleaned, I bought a rebuilt kit and did the whole works. I had the manualto guide me. So new : carb kits, fuel pump, plugs. Just don't know why it revs high in neutral but not in gear. Thank you for your input.

 

[decoy033]

Re: Evinrude won't REV up!!!

I forgot to mention I put new head gasgets on it, compression is between 140 - 150 PSI. Spark seems ok

 

[Walker]

Re: Evinrude won't REV up!!!

It revs high in neutral because there is no load on it other than its own internal friction.<br />Make sure your timer base is moving freely with the throttle linkage. <br />Like is said in my foirst post. If you have compression and you have spark at the right time that only leaves fuel delivery. And 98% of the fuel deliver problems are dirty carbs or floats set wrong.<br />But one other thought. Under a load you might be bleeding spark off through cracked coils or cranks in the insulation on the sparkplug wires.

 

[Scaaty]

Re: Evinrude won't REV up!!!

Take a damn good look at your float bowl venting. Just got done working on a Honda 50 thats just would not take throttle. Tiny little vent in the carb bowl was plugged