* 150 HP Black Max looses power at WOT

[ltkilo2]

HI,<br /> Im new to iboats and i have a problem. I have a 1990 Mercury BlackMax 150 HP. It idels fine and will run at 3000+ RPM at idel. but when you put it in gear, it will run about 1000-1500 and starts to bog down...the more you push it the more it slows down. It wont even get to planing speed. We just had the carbs completely cleand and check, weve check spark plugs and compression. I dont were to look next. Any help would be greatly appreciated. Thanks Agian!!<br /> Kyle

 

[KCLOST]

Re: * 150 HP Black Max looses power at WOT

First, don't rev the engine when not in gear above 2000 rpms... That could cause major problems that you don't want to deal with...<br /><br />Second, What is the actual idle rpm? This is with the engine running in neutral with NO throttle advance.<br /><br />Third, check the fuel bulb when advancing the throttle in gear... Does it go flat? Also check the fuel filter(S)..<br /><br />Forth, when you say the carbs were cleaned and checked, did you mean totally rebuilt following the manual instructions (taken apart, cleaned and set), or did you just spray some carb cleaner in them?<br /><br />Fifth, Pull the cowling off and move the throttle while IN and OUT of gear, does the linkage move properly? <br /><br />This sounds fuel related by the way....

 

[ltkilo2]

Re: * 150 HP Black Max looses power at WOT

Ok, <br /> Thanks for the info about to RPM's. Im not sure what the RPM's are on at idel speed. The carbs were completely torn down and rebulit. Any more info.

 

[CU2NITE]

Re: * 150 HP Black Max looses power at WOT

When you say you've checked the plugs, did you check spark when you did this? Also look at the coils and plug wires when you have the boat running on ears and look for any spark arking over to the block. This can cause problems. Good luck and let us know.<br />CU<br /><br />-------------------<br />RUNNING THE MOTOR WHILE LISTENING TO THE HORN WILL MAKE YOU MORN!!

 

[icesk8s]

Re: * 150 HP Black Max looses power at WOT

Originally posted by CU2NITE:<br /> When you say you've checked the plugs, did you check spark when you did this? Also look at the coils and plug wires when you have the boat running on ears and look for any spark arking over to the block. This can cause problems. Good luck and let us know.<br />CU<br /><br />-------------------<br />RUNNING THE MOTOR WHILE LISTENING TO THE HORN WILL MAKE YOU MORN!!

I'm wondering if it could be the fuel pump. My motor (100hp Merc) was doing the same thing and i was told by the guys on this site to get a new diaphragm kit for my fuel pump. Make sure that you don't have an airlock first (undo the gas cover or check if the fuel ball is collapsed)then move up the fuel line to the fuel filter and diaphragm pump kit. In total the repairs cost me $30. Definetely worth the shot.<br /><br />Scott

 

[wrenchtrnr72]

Re: * 150 HP Black Max looses power at WOT

i've got a 150 merc and had the same problem. what everybody said to check you need to check. i spent 800$ for a new stater and switch boxes, and carb rebuild. my problem was timing, i did not have to spend a dime to fix it, but at least i have some good spare parts?

 

[ltkilo2]

Re: * 150 HP Black Max looses power at WOT

I took It to a shop and they said the power packs were bad... What do yall think?

 

[CU2NITE]

Re: * 150 HP Black Max looses power at WOT

Did you ever check for spark? IF the power packs are the problem you would have had a spark problem. Yes it could be a pack problem.<br />CU<br /><br />-----------------<br />RUNNING THE MOTOR WHILE LISTENING TO THE HORN WILL MAKE YOU MORN!!