Rx7thHeaven
New member
Hello,
I have done some searching and found a post of a similar issue but the OP has never confirmed if his issue was fixed so I decided to start a new thread.
We picked up a 2005 Chap Signature 350 with twin 8.1's and Ocean X drives in September of last year (engines are approx 550hrs). The boat did not have any issues with the engines at that time and would top out right at 50mph with both engines turning from what I remember right around 5k RPM. Most of the time on the boat is spent cruising around in the 1500 rpm range and occasional runs up on plane at 3k rpm which results in a 30-33mph cruise. Cruising at these 2 speeds lightly loaded, I never noticed a problem until this season when we had around 10 people on board and the boat was struggling to get up on plane. What I have ultimately noticed is that both engines run as expected and run equal RPM with equal throttle application until the 3k rpm mark. Once 3k rpm is reached (roughly half throttle on both engines) the port engine will not accelerate any higher. You add in the remaining throttle all the way to full and the port engine does nothing more, while the stbd engine accelerates on up to close to 5k and the prop sync begins deflecting and asking for more port throttle. I am also having an issue with the starter on that same engine, at this point I am unsure if the 2 issues are related, but here is what has happened thus far...
I noticed the power difference and around the same time it started exhibiting symptoms of the starter going out. Sometimes engine would start normally, sometimes intermittent solenoid clicking, and sometimes starter would engage, turn the crank 4 or 5 degrees and then stop turning. You could click the starter a few times and watch the crank and it would turn another couple degrees and then it was like it would release the compression and the engine would start normally. In a time crunch I installed a universal starter from West Marine which worked fine for several days and then started doing the same thing. I thought that maybe since it was a universal for a range of engines, that maybe the 8.1's were just on the limit of its power so I had a starter shop rebuild the factory starter which lasted about 2 days and also began having the same issues. Typically with a hot engine, it starts much better and the issue is most prevalent with cold engines. I am contemplating that I may have a leaky injector that may be hydro locking the engine after it sits for a while causing the engine to be hard to turn over and eating the starters. All electrical connections were checked and are ok.
On the lack of power side, the first thing I checked was fuel pressure which kind of has me stumped also. I checked low side pressure and it was in spec, I then tested the high pressure on the fuel rails on the intake manifold and had zero psi... I thought this was inaccurate and decided to pull the schrader valve and test again thinking the gauge may not be depressing it enough to get a reading... This did not change anything, still zero. I then checked the stbd engine and it was also reading zero at the same port which has me scratching my head.
The strange part about it is the smoothness of the engine prior to and while running at 3k rpm... Its not starving for fuel, it is running perfectly smooth, no stumbles or roughness, its almost like it just hits a computer rev limit (limp mode type thing) and wont accelerate an farther. I have not connected to the engines with a scan tool but I am not getting any alarms indicating a fault code.
One final thing that I just remembered that does seem like a fuel delivery issue: Back in December we participated in a Christmas parade and had the generator running for the X-mas lights while cruising, I noticed that anything over about 1500rpm on the main engines would cause the generator to begin stumbling and coughing like it was not getting enough fuel. Seemed a little weird since to my knowledge, the Gen has a dedicated fuel line directly into the Stbd tank and does not depend on any main engine fuel system... But I could be wrong on that?
Anyone out there with any insight on this would be appreciated... It definitely has me scratching my head. The one thing I forgot to check is what the engine would rev to if in neutral. The next time I am at the boat I will also check that. Sorry for the long post, just trying to provide as many details as I can remember.
Thanks,
Jonathan
I have done some searching and found a post of a similar issue but the OP has never confirmed if his issue was fixed so I decided to start a new thread.
We picked up a 2005 Chap Signature 350 with twin 8.1's and Ocean X drives in September of last year (engines are approx 550hrs). The boat did not have any issues with the engines at that time and would top out right at 50mph with both engines turning from what I remember right around 5k RPM. Most of the time on the boat is spent cruising around in the 1500 rpm range and occasional runs up on plane at 3k rpm which results in a 30-33mph cruise. Cruising at these 2 speeds lightly loaded, I never noticed a problem until this season when we had around 10 people on board and the boat was struggling to get up on plane. What I have ultimately noticed is that both engines run as expected and run equal RPM with equal throttle application until the 3k rpm mark. Once 3k rpm is reached (roughly half throttle on both engines) the port engine will not accelerate any higher. You add in the remaining throttle all the way to full and the port engine does nothing more, while the stbd engine accelerates on up to close to 5k and the prop sync begins deflecting and asking for more port throttle. I am also having an issue with the starter on that same engine, at this point I am unsure if the 2 issues are related, but here is what has happened thus far...
I noticed the power difference and around the same time it started exhibiting symptoms of the starter going out. Sometimes engine would start normally, sometimes intermittent solenoid clicking, and sometimes starter would engage, turn the crank 4 or 5 degrees and then stop turning. You could click the starter a few times and watch the crank and it would turn another couple degrees and then it was like it would release the compression and the engine would start normally. In a time crunch I installed a universal starter from West Marine which worked fine for several days and then started doing the same thing. I thought that maybe since it was a universal for a range of engines, that maybe the 8.1's were just on the limit of its power so I had a starter shop rebuild the factory starter which lasted about 2 days and also began having the same issues. Typically with a hot engine, it starts much better and the issue is most prevalent with cold engines. I am contemplating that I may have a leaky injector that may be hydro locking the engine after it sits for a while causing the engine to be hard to turn over and eating the starters. All electrical connections were checked and are ok.
On the lack of power side, the first thing I checked was fuel pressure which kind of has me stumped also. I checked low side pressure and it was in spec, I then tested the high pressure on the fuel rails on the intake manifold and had zero psi... I thought this was inaccurate and decided to pull the schrader valve and test again thinking the gauge may not be depressing it enough to get a reading... This did not change anything, still zero. I then checked the stbd engine and it was also reading zero at the same port which has me scratching my head.
The strange part about it is the smoothness of the engine prior to and while running at 3k rpm... Its not starving for fuel, it is running perfectly smooth, no stumbles or roughness, its almost like it just hits a computer rev limit (limp mode type thing) and wont accelerate an farther. I have not connected to the engines with a scan tool but I am not getting any alarms indicating a fault code.
One final thing that I just remembered that does seem like a fuel delivery issue: Back in December we participated in a Christmas parade and had the generator running for the X-mas lights while cruising, I noticed that anything over about 1500rpm on the main engines would cause the generator to begin stumbling and coughing like it was not getting enough fuel. Seemed a little weird since to my knowledge, the Gen has a dedicated fuel line directly into the Stbd tank and does not depend on any main engine fuel system... But I could be wrong on that?
Anyone out there with any insight on this would be appreciated... It definitely has me scratching my head. The one thing I forgot to check is what the engine would rev to if in neutral. The next time I am at the boat I will also check that. Sorry for the long post, just trying to provide as many details as I can remember.
Thanks,
Jonathan