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150 Evinrude Intruder

What do you mean by stalls? Does it shut down or develop a misfire? Or, do you mean it simply reaches 5,000RPM and will not increase no matter how much throttle you give it?

If it just goes no higher than 5,000RPM there a few explanations:
1) Check your plugs. If they are old or fouled you could be getting poor spark under load and not getting the power you need.

2) You're over propped. On many applications a 14 1/2 x 24 Raker is the ideal prop for these engines. However, on heavier boats or inefficient hulls you may need to prop down to reach full 5,500 RPM.

3) Do you get a bogging sound if you try to increase throttle past 3/4? If so, this could be a fuel delivery problem. My '96 was doing that after reaching about 4,500RPM. I ended up going through the complete fuel system, new OMS pump, carb rebuild, new float chambers, and that fixed the problem. I knew that I had float needles that were leaking, seepage at the bowls, and excess smoke which meant I the pump wasn't delivering enough fuel to dilute the oil.

These motors are over 20 years old now, so some maintenance on the fuel system is your likely culprit.
 
I have a video but i dont know how to post it.
Stalling out would be the most accurate way to describe it, loses power abrubtly, and then comes back and repeats. I can let out of it and start over and it runs fine up to about 48-4900 rpms.
With that being said, new plugs, new wires, changed power pack, rebuilt carbs, new fuel lines, rebuilt fuel pump, new fuel filter, new OEM primer bulb, new batteries, new thermostat, new temperature sensor...... i know some of these changes arent involved w my issue, but all of this change over time and the exact same issue is still present!
 
Change lower unit oil. Has it run at higher RPM's in the past? If it's always been this way, I think you're over-propped like the other guy said.
 
Out of about 20-25 trips, it has run 5500-5700 rpms 6-7 times, about 17-20 mph faster.
Some of those were long rides, for me, 10-12 miles w zero hiccups
 
Yeah, those "sometimes" problems are the hardest to figure out. So,about 25 percent of the time it runs fine? That doesn't make much sense at all.
 
Run with a timing light.----One cylinder at a time.----Observe the flashing light.-----Might help you determine the issue of loosing spark on one cylinder.----Report what you find.
 
Oldsaltydog said:
Yeah, those "sometimes" problems are the hardest to figure out. So,about 25 percent of the time it runs fine? That doesn't make much sense at all.
Click to expand...
I knew this boat was going to be a project.... but after all that i have done to the motor that is the basic overhaul, i thought it would be good! But sadly enough, it isnt!
 
You do not need a helper to run with a timing light.----This is simple.----You lay the timing light on a seat.----Observe behavior of light when motor falters !----Report what you find.
 
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