Logo
FULL SITE MENU

1998 90hp Stalling under load

quick update

met the mechanic at the lake today and thankfully it failed while he was on the boat. Last time he took it out he could not reproduce the problem.

no definitive diagnosis though. he checked the timing and adjusted slightly and adjusted the ides screws on the carbs. After that we could not get it to fail again, but I am not sure if that is coincidence or because of what he did. The problem is very intermittent.

He did seemed very concerned at how far the motor sat down in the water. Seems the exhaust ports are almost all the way under the water. Thought maybe it was causing the issue like when a cars exhaust was under water. I will say there is alot more weight in the back since I added a 2nd battery for trolling motor and bought a large cranking battery. And it does seem to occur more often when there are 2 people in the boat rather than me alone.

Could there be something to that?

He thought we should raise the motor 1 hole if the adjustments he made today don't change anything the next time i go out.
 
Outboard motors just wont run right with the exhaust relief under water, So that can definately be an issue...
Have the check valves on your recirc system been checked?? These can also cause issues down low...
 
Where does the prop end up when lowered compared to the bottom of boat? Is this motor ment for this boat? Look at the plate should be on passanger side. It will tell you hp and load limits. I would be concerned with not getting good water flow through the engine. But it may have been set up wrong.
 
http://www.onlineoutboards.com Has a diagram for the mounting of the motor.Put a ruler or 2x2 on the bottom of the boat and see where it lines up with the cavitation plate.An inch either way shouldn't matter for the height.Post some pic.
If it only happens under load.Then I doubt it's the exhaust ports.You move fast enough to have them out of the water.
You try running with the lid off?Possible there is an exhaust leak under the cowl.
Going back:Float levels? In the carbs,the needle/seat might have a rubber o-ring that's swelling from ethanol.
Did it do it before the ethanol was introduced?
Not overheating? You test the sensor?Ground out the orange(key on) lead and it should make the buzzer go off.
 
Wow, lots of info....answering in no particular order.

so I tested the temp alarm and it works fine. I get a strong stream out the pee hole and that water is warm when it comes out so I assume it is doing its job.

The check valves have not been checked. Are they part of the powerhead?

The issue only happens when I first put it in gear, so I am not getting up to speed to get the exhaust out of the water. When idling, the exhaust is "bubbling" in the water. Worse when there are 2 people in the boat.

I have only had the boat since 2010, and it was doing it since I had it.

It is the original motor, and has 1065lb rating for gear, motor and people. So Motor is ~3000lbs, I am 200lb, total gear ~150lbs, 3 batteries ~150lbs, trolling motor - 50lbs. So right there I am at ~850lbs. Add one more person and their gear, I am easily over the 1065lbs.

We ran yesterday with the lid off and all the exhaust is coming from the bottom

Float levels? In the carbs,the needle/seat might have a rubber o-ring that's swelling from ethanol. All this has been checked and rebuilt, but he did say he wanted to pull them again and verify the jets are the right size and are not messed up.

He is going to do the motor move for free as he wants to get me right. He asked me to take the boat out and try it again with the adjustments he made yesterday and then we will try the motor lift.

I think we are getting closer and I truly appreciate all of your inputs....
 
Took the boat out last night to test the changes the mechanic made Wednesday and it failed again.

Those relief ports are under water for sure.

Going to take it back and have them pull the carbs again and recheck the floats and jets. Then maybe move the motor up.

Will let you know.
 
Okay, so they raised the motor and rechecked the carbs (no adjustments required).

Took it out yesterday and it did not fail. I only ran it for a couple of hours, but I am cautiously optimistic. I have a 2 day tournament next weekend, so I will know for sure then.


One weird thing did happen though. Carb bowl on 2nd carb came loose and opened up. This happened one time in the past, what could cause that? Loose screw and vibration?
 
Need to see pics of the transom.Pics of the lower unit where it's against the transom.Pics of the prop and exhaust.
You do the high speed stator tests?outboardignition.com
Wish I was in the neighborhood.Where do U live/J
 
What about all the tiny hoses that run around the motor (not the fuel lines). They look pretty crappy. Could there be a hole in one?
 
Is there any possibility that something in the lower unit or the connection between the lower and the top are fouled up? There is a pretty loud "click" when I put the unit in gear.

Just throwing it out there.
 
Quick update...Went through replacing all the vacuum hoses and found that 2 of the 3 T-Check Valves were bad. It is my understanding that if they are allowing 2 way flow of fuel, it can flood the engine. Will replace and see where we are.
 
Back
Top