Mercury 240 EFIRPM Issue

[No Hurry]

Hey Guys,

I've ran into a problem with my boat that I have not been able to solve. I am hoping someone here has some insight. I have a 2001 Islandia with Mercury 240 EFI. When I push the throttle all the up, the engine rpms do not pass 4900 RPMs. After a couple of minutes cruzing at those RPMs the engine jumps to 7000 RPMs. At 4900 RPMs I can't get the boat to plane.

Any suggestions or advice is welcome!

Thanks for look.

 

[Dr Honda]

What have you checked? Other than low RPM... are there any other symptoms?

 

[No Hurry]

I checked the the throttle linkage and I did not see anything out of the ordinary. I greased both ends of the cable with white lithium grease.

Like I said, the RPMs at full throttle do not go past 4900 rpms at full throttle. After couple of minutes of cruzing around the lake the rpms jump to around 7000.

Could it be a problem with the ECU?

 

[Dr Honda]

It could be... but if it was electrical... and you were holding the throttle open, and the RPM's were very low... I would think there would be stuttering, (miss) or other running issues.

I would start with checking the compression. Then, I would check the fuel pressure, on the high pressure rail.

 

[No Hurry]

Since I do not have a copy of the shop manual, can you tell me where the high pressure rail is?

Thanks for the input.

 

[Dr Honda]

There is a schrader valve, on top of the vapor separator, to check the pressure.

To work on this engine yourself... you must get a copy of the factory service manual. It has a bunch of goofy, non-standard things. Also, you need it for all the specs. AND... it has some changes over the years.