engine not going over 3500 rpm

DVILLANDRE

Member
Apr 26, 2015
40
long island
Boat Info
1999 38" sundancer
Engines
454 gas
Both 7.4L mercruiser motors wont go above 3500 rpm. They were running fine 2 weeks ago, took the boat out today and they were very sluggish. Any ideas?
 
IMG_5596.JPG
Fouling on bottom of hull?
 
That's what I thought initially but we rode for quite some time it got a bit better but it seemed the engines weren't getting gas. At first we could only go 11 kts then it went up to 15 kts but they were definitely struggling.
 
It don’t take much growth on bottom and running gear to slow the boat down and 2 weeks in the summer can definitely do that.
Especially with the hot weather we’ve been having!! Short haul, power wash and take it for a run, see the difference!!
 
Check spark plugs. Had the same issue on my starboard engine and it turned out that the spark plug in cylinder 8 was fouled. Changed them all and we are now running great.
 
That's what I thought initially but we rode for quite some time it got a bit better but it seemed the engines weren't getting gas. At first we could only go 11 kts then it went up to 15 kts but they were definitely struggling.
What did you find? Bottom growth? I'm having the same problem now with mine except mine sat for 6 weeks.
 

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