No Full Throttle in gear

I have a 1979 25 HP tiller. My prob is this; the engine starts and idles fine (we've adjusted all linkages), I can even get it to full throttle by moving the gear linkage disconnected, but as soon as I try to run the engine completely hooked up and in gear, It will only run like 1/3 power. I'm running a 12 foot aluminum boat so this motor should be overkill but it seems to be reversed. The engine is not ventilating/cavitating, it's just not accelerating. I've checked and all linkages appear to be fully functioning, any ideas?

Re: No Full Throttle in gear

Do a compression and spark check on both cylinders. A motor can idle just fine on one cylinder.

MAS

Re: No Full Throttle in gear

You are on the right track, the engine isn't getting enough gas but I would suspect a dirty carb rather than the linkage.

You have 3 sets of jets in your carbs,idle, mid and high speed, if any of them are plugged your motor will run like it is a partial throttle.

Start with a compression check as that gives you the general health of the motor if that checks out, @90+, both cylinders within 10% then clean you carbs.

The high speed jets are in the bottom of the float bowl, pull the drain on the bowl and they are inside there.

Also if you don't have a manual get one,OMC, not Clymers, Seloc or any CD,there is a very specific way to adjust the linkage as it is also hooked to the timing ,pretty easy to get things out of whack.

Re: No Full Throttle in gear

i believe 5150abf, is speaking of a larger motor, according to the diagrams, you have 2 jets, high and low. high is a fixed jet in the bottom of the bowl, low is the adjustable jet, on the upper front. Read the TOP SECRET thead at the top of the forum. carb cleaning, and carb adjustments. do spark and compression as mentioned above.

diagrams: http://shop2.evinrude.com/ext/index.aspx?s1=bf6ad09c53cead335fcfd8a6471c0f7f