Loss power/RPM under engine load

[IOU1]

My engine is a 1990 150hp Mariner and my boat has twin 150’s My port side engine is runs ok when not in gear my RPM can hit 4700. But once I put it in gear RPM only hit about 2700. Now this is what I have done to the engine replace stator, rebuilt Carbs, checked out power packs, and replaced trigger. Could the high speed on the stator be bad? Please help.

 

[sledhead041]

Re: Loss power/RPM under engine load

First of all I want to say that you are crazy to even think of bringing it about 1500 rpm without load….have you ever seen a runaway engine? It’s not fun at all it will run by itself without spark and you can’t do anything about it. But on a liter not did this problem just happen all of a sudden or has it progressed over time?

 

[IOU1]

Re: Loss power/RPM under engine load

This first happen when my engine didn't want to start so changed all these parts stator, trigger. Now engine will start with out a problem. But can not seem to reach the RPM's that are need?

 

[IOU1]

Re: Loss power/RPM under engine load

buy the way this happen all of a sudden engines ran fine prior to this?

 

[sledhead041]

Re: Loss power/RPM under engine load

Have you done a sync and link to the timing and throttle?

 

[IOU1]

Re: Loss power/RPM under engine load

Is this part of the requirement this is needed after installing a trigger and stator?

 

[IOU1]

Re: Loss power/RPM under engine load

OK I have done a compression test and this is my results.<br />CLY<br />1 @ 115<br />2 @ 119<br />3 @ 110<br />4 @ 115<br />5 @ 110<br />6 @ 115<br /><br />I did notice that spark plugs on 1,3,5 looked more black and fowled up than the others?

 

[IOU1]

Re: Loss power/RPM under engine load

I also check the spark on 2,4,6 I have about 1/2 inch spark jump to ground and 1,3,5 only have about 1/4 inch. Now what do you think I need to do?

 

[IOU1]

Re: Loss power/RPM under engine load

can any one help me??????????? Please

 

[IOU1]

Re: Loss power/RPM under engine load

Can any one out there help?

 

[KCLOST]

Re: Loss power/RPM under engine load

Ok, if you replaced the triggers, you are in need of a sync and link...<br />Based on what the manual says anyway...Start there. <br /><br />If you are getting spark to all the cylinders that's good. However if it not timed right, you won't get power. Running an engine at idle and in gear makes one hell of a difference.. And don't rev it up at idle anymore like MN mentioned.<br /><br />After the sync and link, let us know...

 

[IOU1]

Re: Loss power/RPM under engine load

Ok I have swaped the blue to blue/white wires and still get the same results. The spark on 2,4,6 I have about 1/2 inch spark jump to ground and 1,3,5 only have about 1/ inch to none. What can I test next please help.