1989 blackmax 150,no power when cold

[vipertec]

I have an 1989 blackmax 150 hp on a 18ft bassboat.a couple years ago it started to have no accel when cold.In gear could not get accel more than 800 rpms.Tryed cleaning carbs,n/g,primer bulb when accelerating,n/g,new plugs,n/g.After 30 min of poor running rpms will slowly bump up,eventually clearing up.then will fine all day.next day same thing.took it to marina,they checked and said ,bad stator,so i replaced with factory part.still n/g.compression all even.I heard that theso called"blackboxes"could be faulty and could be tested with aspark intensity tester,is that true.Also how hard is the water pump,t stats to replace,because I noticed when tried to diagnose last time that the temp was very high.

 

[hkeiner]

Re: 1989 blackmax 150,no power when cold

Seems like testing the ignition with a spark tester and/or a DVA meter while the motor is running poorly would be the thing to do next. Report back on the results and you will likely get some good advice on what to do next.

 

[j_martin]

Re: 1989 blackmax 150,no power when cold

Just for grins and giggles, disconnect the advance or idle module(s). (Whatever is connected to the bias terminals except the jumper between the switchboxes) and try it.

Link-n-sync is critical on that engine. As I remember the pitfalls, one is the throttle pickup timing, and the other is the trigger harness limiting the max timing. (lead dress, wires have to be free to move.)

Another simple thing to check. The pee stream should be uncomfortably hot to touch (140 degrees). If it's cold, the t-stats are sticking or missing. Normally this engine is up to operating temp within 30 seconds of a cold start. It's pretty cold blooded, and will balk, and could cold-stick a piston if run cold.

hope it helps
John