UPDATE - 1982 150 BlackMax - Will Not Accelerate

[ironmachineus]

Engine idles fine, and boat moves fine at slow speed. However, if you accelerate beyond 1/4 throttle, it bogs and coughs and won't accelerate. It doesn't die, but it just sits there bogging down. Occasionally, it will accelerate correctly, but this only seems to happen right after launching the boat. I took it in to the marina, and the said both power packs were bad (they tested voltage or something), and replaced them to the tune of $500. They said compression was fine, and consistent at 110 in all cylinders. I launched again today, and the first run was fine, but after fishing for a while it's now doing the same thing again (bog and won't accelerate). Any help would greatly be appreciated. Thanks!

 

[LaGaviota]

Re: 1982 150 BlackMax - Will Not Accelerate

Re: 1982 150 BlackMax - Will Not Accelerate

I have an '86 Blackmax 150 that is doing the same exact thing. I have replaced the stator, switch box and coils. I have a new tank and 89 octane gas with new line to the engine. Next weekend I will be rebuilding the fuel pump. I think that the fuel pump is my problem. If this doesn't work, then i will rebuild the carbs next. Good luck to you.

 

[Badjet120]

Re: 1982 150 BlackMax - Will Not Accelerate

Re: 1982 150 BlackMax - Will Not Accelerate

if you wish to check you fuel pump, idle the engine and remove the main fuel line from the carb there should be a steady stream of fuel . if you have that the pump is good . you may want to check the main nozzle in the carb as if it is obstructed (with junk) will cause insufficient fuel flow above idle . see your service manual on how to do that .

 

[bulletgwd]

Re: 1982 150 BlackMax - Will Not Accelerate

Re: 1982 150 BlackMax - Will Not Accelerate

My motor ran the same, we chased fuel replacing the fue line, bulb, filter, coupler, cleaned the carbs and replaced every ignition part with no change. Finally bought a "spark gap tester" ($6.99 at Autozone), used a 1/2 inch gap and found two coils had weak spark (spark would jump 3/16 gap). Good luck!

 

[ironmachineus]

Re: 1982 150 BlackMax - Will Not Accelerate

Re: 1982 150 BlackMax - Will Not Accelerate

My plugs don't have gaps - they are surface gaps. If it was a coil, wouldn't it happen all the time? She accelerates fine 1 out of 6 times.

 

[bulletgwd]

Re: 1982 150 BlackMax - Will Not Accelerate

Re: 1982 150 BlackMax - Will Not Accelerate

that's exactly like mine did... it may not be the coils (that's how my mechanic felt) something to try...

 

[ironmachineus]

UPDATE - 1982 150 BlackMax - Will Not Accelerate

Here's the latest. Mechanic says must be the stator. Gets heat soaked and the high speed coils don't conduct properly. Says the bad powerpacks may have ruined the stator, so they needed replacement anyway. Any thoughts?

 

[hkeiner]

Re: UPDATE - 1982 150 BlackMax - Will Not Accelerate

The Mercury shop manual describes various ignition system tests (which require an ohmmeter/multimeter and a DVA meter) to determine if an ignition component has failed. These tests are pretty comprehensive and in my experience a good way to solve an ignition system problem before replacing expensive parts based upon a hunch or gradual elimination of possibilities. The only problem is finding the defective part if it works OK when cool and then fails when the motor/part is warmed up.


I thought I had an ignition system problem on my motor but before I replaced any electrical parts, I did all the ignition system tests and found nothing wrong. I also got a SmarTach meter, which can measure secondary voltage in the spark plug wires (amazing tool!) while the motor is running at idle, while accelerating, or WOT. This was a definitive test for me as I could see that the secondary voltage in the spark plug wires was OK even when the motor was bogging. I then changed my attention to the fuel system and solved my problem. Your results, of course, may vary.