Stall at 1000 RPM Mercury 150 1989

[mwoodard]

OK, I have rebuilt the fuel pump, carbs, fule filter, fule lines (all of them)changed wires and coils.

Boat ran fine first time out after everything was fixed, then on my second trip out the motor ran fine for about 10-15 minutes then just died. It will crank right up and idle just fine. Whenever I "hit it" to get on plane it simply won't go. I can idle around at upto 1000-1100 RPM but if I give it any more throttle it chokes and pukes. This only happens when it is in gear adn in the water. Lifting the throttle tab the engine revs right on up with no misses at all, all the way upto 5000 RPM which is where I am usually running it.

Out of the water (with it's ears on) it will rev right up with the throttle tab OR with it in gear.

Strange stuff...any help appreciated.

 

[Chris1956]

Re: Stall at 1000 RPM Mercury 150 1989

That is not strange at all. It means that your idle mixture is set too lean, or the carbs are gummed up. Since you just messed with the carbs, the idle mixture is likely out of adjustment.

First warm up the motor on the water. Now adjust the six idle mixture screws (at less than 1100RPM) until the motor runs as fast and as smooth as you can get it. Lower the idle speed if necessary to keep it under 1100RPM. Now try to accelerate. The motor will usually stall. If it accelerates properly, you ar edone, if not, open the top carb idle mixture screws 1/8 turn and try to accelerate again. Repeat with mid carb and bottom carb screws, testing acceleration quality each time. Stop adjusting when it works pretty good.

 

[mwoodard]

Re: Stall at 1000 RPM Mercury 150 1989

I will give that a try.

My mechanic is saying it is probably the stator or powerpack.
He is the one who rebuilt the carbs and he has a good reputaion around the lake.

Would you still think it is idle mixture if it was running fine and just simply stalled?

The boat ran great the day after he rebuilt the carbs, got on plane real fast and ran good for the 30 minutes I tested it. Next time out I rode about 10 minutes to my "Top Secret Fishing Hole" and it seemed to lunge a bit right before I brought her down off plane. When I went to go back to the ramp is when the issue started. Had to idle back 7 miles at 1000 RPM.

 

[Chris1956]

Re: Stall at 1000 RPM Mercury 150 1989

That motor does have a high speed and low speed stator. Perhaps the high speed stator winding failed. You should be able to ohm it out. The procedure will be found on the CDI.com or Dolphinmarineservices.com web sites. Look for the proper ADI troubleshooting procedure for your motor.

 

[mwoodard]

Re: Stall at 1000 RPM Mercury 150 1989

OK, got it on the lake today and ti ran like a beast for about 15 minutes then started acting up again. Went back to the ramp where I could work on it while the prop was in the water. It appears the bottom two carbs were not getting fuel after the problem starts. Could this explain why it runs fine with no load?

I think the bowls are emtying out when it starts sucking all that fuel under load. Does this make any sense?

Since it is the bottom two carbs I would assume it is not a fuel pump issue as that would show on the top two carbs first correct?

I am thinking that the spring may have gotten out of whack when it was reassembled which would allow the needle valve to stick.

Could I be on the right track with this diagnosis?