Hi last season I bought a 2001 Sea Ray
and from the very beginning I have been having an issue. I run the boat
for about an hour between 25-32 mph upwards to 3100 rpm
and it runs beautifully. The engine
sounds great and the temperature is good right at 170. After about an hour when I’m cruising all of a sudden the boat slows down to about 20 mph and then about 18 mph. When this happens I have tried to use the throttle and even almost to full throttle the boat is only running at 2500 rpm
and going a max of 18 mph. This happens the whole ride back to the dock
and even though its running only 18 mph it sounds good and engine
temp is good.
I dropped this off at a Mercruiser authorized mechanic
2 weeks ago. At first they suspected that it’s the fuel tank
vent. They asked me to open the fuel
cap and if I hear a swoosh and it clears the issue then thats the issue. I tried that, I did not hear a swoosh of air but it seem to clear the issue temporarily. They told me it was the fuel tank
vent and replaced it.
I picked up the boat and ran, it sounded great again and this time it only took about a half hour and it slowed down again. I brought it back to the marina, they were thinking that its the fuel filter
. They replaced that but it did not clear it.
Next they hooked up a computer to it and it did a recording. They studied the computer results and believed that the issue was with the map sensor. They said they had a specialist from Mercruiser look at it and they thought the same thing. The map sensor cost $250 to replace and I gave my consent and they replaced it. They took it again for a spin but said unfortunately it did not resolve the issue.
Today they told me that they changed spark plugs, distributor cap, and rotor to eliminate the possibility and tested it again, but the problem still exists. So far we have fuel
tank vent, fuel filter
, map sensor, spark plugs, distributor cap and rotor replaced but it’s still occurring.
This is starting to become a costly repair and wondering if anyone has any thoughts or ideas as to what could be causing this and would there be a more effective way of troubleshooting this such as replacing the parts
that could be related to this. I had an engine compression
analysis done last year and it was all good. I also had the boat wintered and engine commissioned. They said the engine compression
test came back great and the mechanic
who looked at my boat in the spring said he found virtually no issues.
The fact that it only occurs after a 1/2 hour to an hour sounds to me like something is heating
up and it sounded too me like a sensor issue but the map sensor was replaced and it’s still occurring.
Any opinions or suggestions are appreciated.