Mercruiser 5.0 mpi only 4000 rpm

[Searay240sd]

I have 2007 sea ray 240sd with a 5.0 mpi with a bravo 3 with 22p props. Engine serial number 0w661357. I recently boat the knowing it had issues. I can not get the boat above 4000. When I 1st got the boat it would go above 3500. I have changed the plugs with NGK ITR4A15, new cap rotor, wires, fuel filter, sent injectors out to cleaned. Compression in one cylinder was around 130 with 40 percent leakage in exhaust. I had 3 seats crack on the exhaust. Replaced both heads now boat had 170 psi on all cylinders. Fuel pressure is steady at 43 psi. I ran a separate fuel tank and had no improvement. I ONLY HAVE 13 INCHES of vacuum. I have no vacuum leaks. I have a tech mate its showing 100 percent power. At idle spark advance is all over the place from -2*-8*. Bost had 25* at 4000. If I turn the crank the rotor immediately moves so I don't think there is slop in timing chain. I had 13 inches of vacuum before head job. Exhaust seems to be clear, both flappers are in y pipe. Bottom is cleaned. TPS is showing 100% open 4.3 volts. Alternator is putting out 14 volts. The boat has no power after 5/8 throttle, if you give it more gas the engine does not respond. Any inputs would be appreciated. Thanks.

 

[Searay240sd]

Oil pressure is 50 psi, boat ran at 160*. There is also no faults. Thank you

 

[alldodge]

Check you timing. Bring No 1 to TDC and see if the distributor is as shown below

 

[Scott Danforth]

Drop prop pitch

 

[Searay240sd]

I checked the distributor about 5 times, it's set correctly. The prop on the boat is the one that came with the boat from the dealer, according to the spec sheet the bost tested at 5000. I have all the original paper work

 

[RaceCarRich]

I have 2005 version of that boat. I’m just learning it now but figured I’d mention something you probably know already. There are 2 filters in the cool fuel module. Did you change both?

EDIT: just reread that fuel pressure remains steady. Assuming that means while running up the rpm’s. If so, ignore the filter idea.

 

[alldodge]

What is your MAP readings as the rpms increase and once its at 5/8 throttle does the MAP change anymore?

 

[Searay240sd]

Yes I changed both filters and pressure remains steady at all rpms. I will read maps sensor tomorrow and get back to you. Thanks for everyone's input

 

[89retta]

I checked the distributor about 5 times, it's set correctly. The prop on the boat is the one that came with the boat from the dealer, according to the spec sheet the bost tested at 5000. I have all the original paper work

So you have an 11 year old boat with original props. I doubt that they are in new shape. Replace them with a lower pitch of new props. That will make a big difference

 

[Searay240sd]

Boat has 135 hours on it. Props look in good shape, there is zero vibration.

 

[Rick Stephens]

Any chance it is somewhat heavier than when new?

 

[Searay240sd]

I thought about that but the boat d ok sent show any evidence of being wet. It just seems like the engine stops working at a certain rpm like it can't suck in any more air. I scope the exhaust and it was clear.

 

[Searay240sd]

With of 13 inches of vacuum that's telling me something is wrong.

 

[DouglasW]

Why? At what RPM and throttle angle is that? Vacuum can be anywhere from 28 to 5 depending on the engine speed, throttle and altitude.

 

[Searay240sd]

13 is at idle, and at sea level. That is low for a stock gm motor.

 

[DouglasW]

...

 

[Searay240sd]

What is your MAP readings as the rpms increase and once its at 5/8 throttle does the MAP change anymore?

There was a lot of boat traffic and I was by myself but at WOT it was reading 14.9. I also saw that my spark advance was 26*. Does any one know what time timing should be. Thanks.

 

[alldodge]

Most cases the MAP reads in kpa, but if 14,9 is Hg then that collates to about 50 and which says the motor is only getting 50% of the fuel available. Your TPS is at 100% but fuel is at 50%. Would like to see a full range of how the MAP changes

 

[Searay240sd]

Most cases the MAP reads in kpa, but if 14,9 is Hg then that collates to about 50 and which says the motor is only getting 50% of the fuel available. Your TPS is at 100% but fuel is at 50%. Would like to see a full range of how the MAP changes

Thanks, I will get the results this weekend. Are u saying that the map sensor should be reading 29 hg at WOT? What about total timing is 26* total right?

 

[Searay240sd]

I believe the tech mate is reading it in psi. So 14.9 is 100%. At idle I have 13 inches of vacuum and it reads 8.9