1985 25HP Evinrude highspeed throttle issue only when in water. need advice

Here is the scoop.

MOD. No. CE25TECOS

i have a 1985 Evinrude 25HP Engine with a 35HP Carb and Intake installed from same year engine conversion and boat ran beautifully past two years no hickups. i went away for a bit and didnt use the boat for an entire summer last year. brought it out onto the water 2 weeks ago and ran nice. Motor started to act up due to a clogged vent on the tank. fixed issue and have had an issue ever since with the high speed when open throttle.

it boggs down once i take it over 25% throttle and sounds bad (deep gurggling), but no engine cutout. engine goes right back to nice idle when i let the throttle off and stays running. if i prime the engine with the primer beside the electiric start button with the throttle wide open, the boat takes off and skips across the water at like 30mph with smooth operation.

note: primer is taking the fuel from the bottom of the bowl on the carb, so i know the fuel pump is working and due to the fact it is brand new only 3 days ago and that the bowl is always full. Also, when the motor has a set of water muffs on it while on dry land at my house, the engine comes alive in neutral and in gear. revs and peaks out with wide open throttle no hesitation. water flow stream is constant and have no issues. issue starts in the water only while boat is floating.

I cleaned the carb out best i can, just everyone keeps saying to clean out the high speed jet. my question is, Where is the high speed jet located on the carb? and is there a highspeed needle as well? i have no diagrams what so ever on this engine or carb. i wanna take it to a mechanic, but wanna try everything possible myself first. so i can get the easy stuff outta of the way. any advice or links would be amazing. Thanks again.

list of new parts:

New fuel pump
new spark plugs
cleaned carb, but cant find info on high speed jet
new gas lines and all new hose clamps.
all greased cables and fully functional carb butterfly.
starts up with no issue and idles perfect. revs out in gear on dry land but boggs bad when in water.

Morgan

Re: 1985 25HP Evinrude highspeed throttle issue only when in water. need advice

Morgan, the high speed jet is located in the bottom of the carb bowl and there is no needle or adjustment needed for it.
See marineengine for a parts catalog for your motor.
FYI. Never high rev your engine in a bucket or on a hose, i.e. no load. Good luck.

Evinrude Parts & Johnson Outboard Parts at MarineEngine.com

Re: 1985 25HP Evinrude highspeed throttle issue only when in water. need advice

Thanks I will try tonight and clean it right out. I will msg back. Lets see what happens. I tried everything else.

Re: 1985 25HP Evinrude highspeed throttle issue only when in water. need advice

alright here is what i have done. new carb rebuild kit with brand new jets and lean rich fuel mixture screw and gasket, and high speed gasket and jet. complete cleaned out and put back on motor. starts up perfect and screams across the lake.

issue i am finding. i counted 27 1/2 turns when taking out the lean mixture screw top middle front. so when i re installed it i counted back 27 1/2 turns.

at high rpms it feels like it hits top rpm, but there is a hesitation pulse in the rpms that starts up about 15 secs of 3/4 and full open throttle. every 3 secs it feels and sounds like it drops 600 rpm say (guesstiment) and pulsates. half throttle smooths right out and sounds good. runs a bit ruff at but smoothes out if you give it a couple shots of gas.

i know that there is some adjustment required, but my question is where do i start and whats the best way to tune these carbs. at med RPM, high RPM ? is there a tuning procedure?

Thanks

Morgan

Re: 1985 25HP Evinrude highspeed throttle issue only when in water. need advice

At full throttle, the rich/lean control has no effect on the motor. It controls the slow speed (less the 1/3 throttle). I would re-visit your fuel tank issue.

Re: 1985 25HP Evinrude highspeed throttle issue only when in water. need advice

Disregard the 27-1/2 turns of the slow speed adjustable needle valve and do the following.

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

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Did you actually replace that high speed jet or simply clean it. If replaced, did the replacement have the same number imprinted upon the side of it. If simply cleaned, it is best to carefully clean the jet with a piece of single strand steel wire as solvent just doesn't do that cleaning job properly.

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Check and make sure that the scribe mark on the cam that slides against the throttle cam roller is dead center with the roller as the throttle butterflies just start to open.

Also... the throttle cam roller should be about 3/8" in diameter. Some of those rollers have a clear sleeve covering a much smaller diameter black roller. The clear sleeve has a flaw that causes it to break away, resulting in the roller being much smaller than it should be (approx 3/16" or so)... this causes a glitch in the sync & link setup. If this is the case, replace the roller.

Re: 1985 25HP Evinrude highspeed throttle issue only when in water. need advice

i just re used the SS needle but i actually replaced the high speed jet and gourmet. it was an OEM 25HP carb rebuild for that year from Evinrude/Johnson. fits 25/30/35/40HP engine carbs. cleaned out everything really well. IM getting some good vibes from the engine but i always have when its not in water. haha. i looked at when the carb butterfly seems to just open that the white slider under the flywheel isnt center of the roller but about 40% the way to center. but no matter how open i make the throttle the roller doesnt go to the middle, wish i could up link pics.

i will try it on the lake tonight and see what happens and report back.

thanks again

Re: 1985 25HP Evinrude highspeed throttle issue only when in water. need advice

Here is a fyi as well. The black rod that pushes up and down on the side of the motor that connects to the forward neutral reverse selector. When in neutral doesn't allow the the white unit to spin past half. Wish I knew what there names where. So please excuse me for poor terminology. When in rev or forward the black peice moves down but still blocks the main "timing advance" peice from turning all the way still. Or is this normal? Or should it be able to glide over too of that selector peice? This would allow that unit to spin forward another 1 1/2". The black rod when in rev or forward is only stopping it by 1/16" of an inch.

Re: 1985 25HP Evinrude highspeed throttle issue only when in water. need advice

The plate under the flywheel that turns to advance the spark when throttle is applied is called the "timer base" (on older motors = armature plate). The black rod is simply a shift lockout rod that prevents one from applying too much throttle while in reverse or neutral... it also normally prevents shifting out of gear when at higher rpms (models vary).

In "Forward" gear, whether the engine is running or not, the "timer base" under the flywheel should swivel/turn as throttle is applied and it should bottom out upon the rubber base of the full spark advance screw at full throttle. Does it go up against that stop?

That spark advance screw is located in the Port Manual Starter Support bracket and is locked in place with a 7/16" nut and washer.

Re: 1985 25HP Evinrude highspeed throttle issue only when in water. need advice

That black and rod stops the timing advance ring no different then rev or neutral. It moves down but not outta the way. Seems thats where my issue maybe. I have to allow that black rod drop about 1/8" more to allow it to move overtop of it. It doesnt turn more than 40% than what it should. That black rod when you go from neutral to forward acts like its in neutral when in forward. I have to adjust it so when in forward it bypasses over top of it.

Re: 1985 25HP Evinrude highspeed throttle issue only when in water. need advice

waybetterhd said:

i just re used the SS needle but i actually replaced the high speed jet and gourmet.

Click to expand...

I just noticed that small statement about a high speed jet and grommet.

There is no grommet associated with the high speed jet. Are we speaking about the same jet? Describe the jet you're speaking of and where it is located.

Re: 1985 25HP Evinrude highspeed throttle issue only when in water. need advice

The jet located in the bowl of the carb. It has a plastic washer that comes with it. So the mechanism that hold advancing timing ring when in gear wouldn't go to the black stopper as you asked. It wont advance past the plastic black locking rod connected to the neutral rev forward selector. There is no adjustment, so we just shaved it that 1/8" on the plastic and now it moves freely and bottoms out on the rubber stopper. My buddys 35hp1983 evinrude has that black peice completely removed, but he has the steering wheel assembly. So shaving it didnt seem like a huge deal. Better than screwing around with linkages. And it still stops it in neutral from advancing.

THANKS

Re: 1985 25HP Evinrude highspeed throttle issue only when in water. need advice

waybetterhd said:

The jet located in the bowl of the carb. It has a plastic washer that comes with it.

Click to expand...

That sounds like you're speaking of the "vertical" high speed nozzle and its gasket that presses against the float chamber, NOT the high speed jet that is threaded into the center of the float chamber in a "horizontal" position way in back of the drain plug screw.

The high speed jet is removed and installed with a special screwdriver tool that is inserted in and thru the drain plug screw's access hole. If this jet is clogged, the engine will die out when the throttle is advanced. See #50

This float chamber is not identical to yours but the jet location is the same.