Mercruiser 5.0 mpi only 4000 rpm

[alldodge]

If its 14.9 psi then its correct

 

[Searay240sd]

Thanks, does any one know what the total timing should be.

 

[alldodge]

Thanks, does any one know what the total timing should be.

Its not listed in the manual, and in previous motors they were between 22 to 26 degrees. The PCM controls the advance and your getting 26 so I would think your good

 

[Searay240sd]

Thanks also do you see anything wrong with the timing bouncing all over the place st idle? It goes from -2 to+6

 

[alldodge]

Thanks also do you see anything wrong with the timing bouncing all over the place st idle? It goes from -2 to+6

No its normal, mine does the same thing and always has.

 

[Searay240sd]

Thanks, any input on the low vacuum at idle.

 

[alldodge]

I'm not use to seeing that low a vacuum at idle for a good running motor

 

[danilbap85]

Hello Searay240sd . Just wanted to know if you ever get to fix this issue? I haven't being able to bring my rpm's above 4000 and boat runs 40mph. I've done lots of things in the engine but the problem remains. thanks!

 

[QBhoy]

Hi. What speed were you getting at 4000 rpm ?

 

[Superjetjim]

I have the same as well, 4.3MPI, 4,000 RPM and 40mph. Have dropped from 21p Ali to 19p stainless and made no difference.

 

[danilbap85]

Hi. What speed were you getting at 4000 rpm ?

Hey! I'm getting around 38mph

 

[QBhoy]

Hey! I'm getting around 38mph

Ok. So are there any indications that this 4000 rpm is a an electronically limited ceiling on the rpm ? Are there any beeps on the buzzer or signs of ignition being cut at that rpm ?
Or is it more like it’s running out of puff at that ? Any signs of it backfiring or being fuel starved perhaps ?

 

[danilbap85]

ve the same as well, 4.3MPI, 4,000 RPM and 40mph. Have dropped from 21p Ali to 19p stainless and made no difference.

Ok. So are there any indications that this 4000 rpm is a an electronically limited ceiling on the rpm ? Are there any beeps on the buzzer or signs of ignition being cut at that rpm ?
Or is it more like it’s running out of puff at that ? Any signs of it backfiring or being fuel starved perhaps ?

The most I get of on an good day is 4070rpm more less with no alarms or beeps. No starvation at all, new gas pump and the gas pressure before the injectors rail is 43psi. Cool fuel module is in perfect conditions with new filters. Original props 20 pitch in my Bravo 3, the mechanic check props and there's no visible sign of damage on them.