6.2 mercrusier lacking power and won’t run more than 4400 rpms

[Coy]

Hi I have been a member for a while but have never made a post so bare with me I’m new to this. So I purchased my 2007 310 sea ray sundancer with twin 6.2 mercrusier engines with zf v drives about one year ago.port engine was supposedly a reman engine replaced 6 months prior. I transported the boat from South Carolina to Louisiana and I had a inspection done mechanically etc..
They told me the port motor was lacking rpms and they said it was caused by a issue with the prop or build up. So I got it home put it in the water and found that
The port motor was running about 400 rpms less than starboard motor. So max rpm for port motor is around 4400 and the starboard motor easily gets to 4800 as it is setup for. So I had the props removed and they had some dents and growth. Had them balanced and cleaned reinstalled still the same issue. So I continued to drive the boat for a few weeks and the port engine that was replaced dropped a valve and then it threw a rod out the pan. It was a reman marine engines for less was the tag on it.
So I installed a quicksilver long block
New injectors, new plugs, new wires, cap and rotor. So got the boat back in the water after engine replacement still runs the same way won’t accelerate as fast as the starboard motor or exceed 4400 rpms so since then I have swapped the following parts from other engine to try to rule it out
Both fuel pressure regulators and vacuum line,map sensor,crank and cam sensor. Fuel pressure maintains 45 psi
Timing at wide open throttle reads 24 degrees btdc on both engines.Also I notice that the port engine has a stronger smell of gas like it’s running rich. I’m a diesel tech by trade so I understand how it all works but I’m stumped and come to find out after we called mercrusier with the engine serial number this has been a issue for some time with this port motor. I’m running out of things to try and getting frustrated with it and I have had a few mercrusier techs look at it dumb founded. Sorry for the long post it’s been a long year of trial and error I’m exhausted.

 

[scoflaw]

Fuel pressure should be at 42. 24 degree's is low.

2007 was a year with the CF3 issues. Have you checked for a dead cylinder? Have you had the injectors serviced ?

Pretty sure that motor is a 5k to 5200 rpm.

 

[dtfeld]

Reaching here, but have you checked the V drives to make sure they have the same ratio on both sides?

 

[Coy]

Fuel pressure should be at 42. 24 degree's is low.

2007 was a year with the CF3 issues. Have you checked for a dead cylinder? Have you had the injectors serviced ?

Pretty sure that motor is a 5k to 5200 rpm.

Well the starboard will exceed 4800 if I push it and both motors have same fuel pressure and timing reading on factory scan tool. It has 4 blade props that are spec to 4800 rpm per the manufacturer

 

[Coy]

Reaching here, but have you checked the V drives to make sure they have the same ratio on both sides?

Far as the tags go they say the same thing but unsure if the guts are the same. Is there a easy way to tell?

 

[Coy]

Fuel pressure should be at 42. 24 degree's is low.

2007 was a year with the CF3 issues. Have you checked for a dead cylinder? Have you had the injectors serviced ?

Pretty sure that motor is a 5k to 5200 rpm.

Injectors are brand new on both engines and the motor with the issue is brand new and is doing the same thing the old engine was doing. Runs and idles fine no smoke or vibration just doesnt have the get up that the old 300 hour starboard motor has and lags behind about 400 rpms

 

[Coy]

Injectors are brand new on both engines and the motor with the issue is brand new and is doing the same thing the old engine was doing. Runs and idles fine no smoke or vibration just doesnt have the get up that the old 300 hour starboard motor has and lags behind about 400 rpms

Also ever part that has been replaced is oem

 

[scoflaw]

MERCURY® MERCRUISER®
6.2L
Rethink the V-8.


A 6.2-liter V-8 engine with unparalleled torque and acceleration to get you on plane quickly and smoothly.

• HP / kW 350 / 261
• Maximum RPM (WOT) 5000 - 5400
• Engine type V8, 2-valve/cylinder pushrod
• Displacement (L) 6.2
• Fuel delivery system Computer controlled Multi-Port Electronic Fuel Injection (MPI)

The specifications displayed here may not be indicative of the entire engine family; click on the “See All Models and Specs” link to view the specs in detail.
Isn't this what you have? Says 5k to 5400
See All Models and Specs

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Rethink the V-8.
We certainly did. Everything, part by part, system by system, with a total design and engineering commitment to marine use. The result? A 6.2-liter V-8 engine with unparalleled torque and acceleration to get you on plane quickly and smoothly. A whole

 

[Coy]

MERCURY® MERCRUISER®
6.2L
Rethink the V-8.


A 6.2-liter V-8 engine with unparalleled torque and acceleration to get you on plane quickly and smoothly.

• HP / kW 350 / 261
• Maximum RPM (WOT) 5000 - 5400
• Engine type V8, 2-valve/cylinder pushrod
• Displacement (L) 6.2
• Fuel delivery system Computer controlled Multi-Port Electronic Fuel Injection (MPI)

The specifications displayed here may not be indicative of the entire engine family; click on the “See All Models and Specs” link to view the specs in detail.
Isn't this what you have? Says 5k to 5400
See All Models and Specs

Find a dealer
Compare
play video
play video

Rethink the V-8.
We certainly did. Everything, part by part, system by system, with a total design and engineering commitment to marine use. The result? A 6.2-liter V-8 engine with unparalleled torque and acceleration to get you on plane quickly and smoothly. A whole

Mine is the older generation 6.2 liter I think it’s rated for 325 horsepower. It’s basically a 350 bored to a 377 with pcm 555 computer system.

 

[Coy]

Mine is the older generation 6.2 liter I think it’s rated for 325 horsepower. It’s basically a 350 bored to a 377 with pcm 555 computer system.

MERCURY® MERCRUISER®
6.2L
Rethink the V-8.


A 6.2-liter V-8 engine with unparalleled torque and acceleration to get you on plane quickly and smoothly.

• HP / kW 350 / 261
• Maximum RPM (WOT) 5000 - 5400
• Engine type V8, 2-valve/cylinder pushrod
• Displacement (L) 6.2
• Fuel delivery system Computer controlled Multi-Port Electronic Fuel Injection (MPI)

The specifications displayed here may not be indicative of the entire engine family; click on the “See All Models and Specs” link to view the specs in detail.
Isn't this what you have? Says 5k to 5400
See All Models and Specs

Find a dealer
Compare
play video
play video

Rethink the V-8.
We certainly did. Everything, part by part, system by system, with a total design and engineering commitment to marine use. The result? A 6.2-liter V-8 engine with unparalleled torque and acceleration to get you on plane quickly and smoothly. A whole

Prop shop called mercrusier with my serial numbers and was told to spec them for 4800-5000 and when I hook my scan tool up it shows the same rating.

 

[dtfeld]

Far as the tags go they say the same thing but unsure if the guts are the same. Is there a easy way to tell?

If the tags are the same, very unlikely they are different ratios. One other question. Where are you reading the RPM's from? Are you using a good strobe tach?

 

[Coy]

If the tags are the same, very unlikely they are different ratios. One other question. Where are you reading the RPM's from? Are you using a good strobe tach?

We are going off computer and dash. But not only is it lacking rpms it will not ramp up as fast as the other engine. The entire rpm range if you floor both engines the port will follow behind the starboard 300+ rpms and seems much worse when you top 3000 rpms the starboard really starts blowing past the port. You can tell it’s weaker because if I lower rpms on starboard and try to bring up port it won’t come up higher until I bring the starboard back up. As if it’s relying on its power to continue to be able to accelerate.

 

[dtfeld]

Hmmm... I would get a good quality tachometer and verify exactly what RPM you have on the flywheels. Sea Ray tachs are worthless. The computer is another matter. Do both engines have the same ECM and program flashed?

 

[Coy]

Yes both engines run a pcm 555 system I have swapped them and it does the same thing but I’m guessing they are flashed port and starboard because when I swap them the gauges one the dash reads backwards. Like starboard is port and vise versus.

 

[scoflaw]

Where did you buy your injectors? Unless you paid at least a 100 apiece they're probably China knock-offs. Had a similar issue last year and was missing 400 rpm's.

 

[Craig]

Checked the cool fuel 3 thing? They are filters in it also. Are they stock props? Should be slight difference in pitch from counter rotation.

 

[Coy]

Where did you buy your injectors? Unless you paid at least a 100 apiece they're probably China knock-offs. Had a similar issue last year and was missing 400 rpm's.

Oem injectors brand new on both motors

 

[Coy]

Checked the cool fuel 3 thing? They are filters in it also. Are they stock props? Should be slight difference in pitch from counter rotation.

Yes both cool fuel modules have new housings and filters and screens have been replaced. Including regulators. Props have been removed and balanced and check by a very reputable company about a hour south from me that does tons of ships etc..

 

[Craig]

Throttle body?

 

[Coy]

Throttle body?

When I replaced the engine I cleaned the intake out and removed throttle body and cleaned all ports out for iac. Didn’t see any issues. Is there something that I should be looking for that is a known problem? It’s very simple design just a lever and flap