1996 Evinrude 112 spl - not getting wide open throttle after warmed up

[Marc Peternell]

Hi Everyone,
1996 Evinrude 112 spl. The the engine is not warmed up yet, it performs perfectly. Once warmed up, it doesn't have the proper power, takes a while to get on a plane, I have to give it full throttle and it still lacks power. Since it performs fine prior to being warmed up, I'm thinking that it has something to do with the choke. I've recently switched from being an i/o mercruiser guy to an outboard and I know nothing about how the carb and choke system works, but it feels like somethign just isn't opening up.

I've done a compression test and it has great compression 120 in all cylinders. New fuel pump, spark plugs/wires.

What should I look for? Any thoughts on how I could diagnose this issue would be really appreciated.

 

[ondarvr]

Check for spark when it acts up, coils can work well when cold and then fail once they warm up.

 

[Marc Peternell]

I will do that..Thank you. I guess I just figured that if it has good spark when cool, then spark isn't the problem. I didn't know that coils can fail once warmed up.

 

[emdsapmgr]

As ondarvr mentioned: Heat is the enemy of all weak ignition components. (stator, timer base and power pack) They tend to work when cold, then not- once the engine warms up to "normal' operating temps. The 4 coils are probably not the problem. They fail rarely, and then not all 4 at once.

 

[ondarvr]

All 4 wouldn't be failing at once, it still runs, just with less power when he tries to go fast, that's why I suggested to check for spark on each cylinder when it acts up.. At one time or another I've had to change a coil or two on just about every crossflow I've owned, now I change all of them at the same time after one goes bad. It could be any ignition component though.

 

[ondarvr]

One other thing, you have a manual primer (choke) on this motor, it's not automatic, so when you stop pushing the key in it stops working. If it leaked fuel past the valve it would run terrible almost immediatly after it started, and would have less affect at higher RPMs.

 

[Marc Peternell]

Well, first I will test the spark and see if it is a coil, or I may just buy 1 coil and when the engine does it, switch the new coil in and out with the other coils to see if it makes a difference. Would it have weak spark or no spark?

 

[Marc Peternell]

Update: It is not electrical. 1. The boat runs perfectly when going slow and doesn't sputter at all when even giving it full throttle. 2. When I'm trying to get on a plane (where the problem exists), if I bump the key in to have the primer add some fuel, the engine revs and pops the boat up.

So, I'm not getting enough fuel. I'm thinking that either:

1. My high speed jet(s) are clogged?
2. Fuel pump? Although I did rebuild my fuel pump. Question: If it is a fuel pump issue, wouldn't it be starving for gas at the primer also?

Any responses are greatly appreciated. I've seen videos where people run a high concentration of B12 Chemtol through the engine, but they only do that at idle, so I don't think that would clean out my high speed jets. Any thoughts?

 

[emdsapmgr]

You can do a quick fuel test. Take a buddy boating with you. Advance the throttle for WOT performance. Have your buddy constantly prime the fuel hose bulb. This will force extra fuel into the carbs. If the engine runs WOT just fine, as long as you constantly prime the fuel hose bulb, you have a fuel restriction, which could include a weak fuel pump. This is similar to your hitting the choke and the boat runs better (more fuel).

 

[Marc Peternell]

Thank you everyone for your responses. I pulled the carbs off and took them apart and found that parts of the bowl gasket had come apart (I don't even know if the proper gaskets were used) and the pieces of the gasket were causing the restriction. I cleaned out the high speed jets while I was in there as well. Boat is running great. The problem was with the carb.

 

[rothfm]

Thanks for updating! Helpful to others.