Mercruiser 454' stalling problem

[ALLTERRAIN RED]

I have a 1999 32' Wellcraft with twin 454 Mercruisers. Engines are reguarly serviced and run well. Starting last year and continuing this year, my port engine after running for a while at 3000 + RPM's and with me reducing the RPM's to 1000 or less, my port engine starts to stutter and surge to the point where my engine stalls out. Folks have suggested that "vapor lock" may be the problem and to run the blower or open the hatch. The solution does correct itself when the engine cools for 7-8 minutes. The engine does not read hot or lose oil pressure. Everything seems well with the guages except for the surging that occurs. This does not happen any other time for the most part. The engine runs well above 1000 but when running and heating up for a while this condition happens when I start low idle cruise. I did change the impeller on the SB engine this spring and most likely will do the port engine this coming week. Does this seem to be a fuel pump problem? All belts are new and the engine is serviced regularly by my mechanic, but he is not a marine mechanic and is stumped by this problem. The engines are both raw watered cooled.
One theory I was thinking is that the impeller on the port engine, after running at 3000+ RPM's is not getting enought water to cool the engine and the sensor's set off and the alarm sounds and the engine stalls. Will the new impeller solve the problem or am I lookinig for another solution?
Thanks!

 

[CharlieB]

Re: Mercruiser 454' stalling problem

1st problem, you're in the Outboard Forum, repost in the Mercruiser Forum

2nd problem, You didn't mention the alarm going off until near the end of your post.

Two temp sensors on each motor, one for temp gauge and another for the EFI and alarm. Either MAY be in error. Regardless, change the impeller FIRST, just to be sure. Swap sensors with other motor one at a time, see if problem switches motors.

 

[ALLTERRAIN RED]

Re: Mercruiser 454' stalling problem

Thanks CB, my bad on the forum. Will try your suggestions and see if it works. First time on this site,thanks

1st problem, you're in the Outboard Forum, repost in the Mercruiser Forum

2nd problem, You didn't mention the alarm going off until near the end of your post.

Two temp sensors on each motor, one for temp gauge and another for the EFI and alarm. Either MAY be in error. Regardless, change the impeller FIRST, just to be sure. Swap sensors with other motor one at a time, see if problem switches motors.