Sorry for this... ive read and contributed to a lot of posts regarding not reaching max rpm at wot. Heres the story...
1998 volvo penta 5.0gipbycce with a dp-sm 1.95:1 outdrive. The boat has been sitting for over 10 years. I spent a year trying to get this into shape to launch. Engine was frozen... patience and marvel mystery oil freed it. Replaced the starter, cap rotor, plugs, manifold, risers, bellows, fuel filter, oil, oil filter, thermostat, thermostat housing, water pump impeller, and changed gear lube. New oil pan as well as a couple other things im sure I'm forgetting.
At any rate, I got her running and splashed a month ago. Sounds good, runs good. The only thing is, i only get 3800 rpms. Im using the origonal props which are in good condition. I replaced the high pressure pump and tested fuel pressure which was 30psi. Pipe doped all fuel lines and i didnt see any air bubbles during a fuel test. I sent out the injectors to be tested, flowed and matched. I bought a rebuild kit for the tbi and cleaned and replaced everything. Cleaned out the vst and rebuilt the fuel pressure regulator. Today after puting 25 hours on it i changed the oil and filter and also the water sep fuel filter. The oil seemed dirty, which i expected since the motor was frozen. Oil wasnt burned or milky, it just seemed a bit dirty. The fuel filter had some setiment in it, but no water. I should add that there was 150 gallons of 10 year old fuel in it. I pumped all that out. I would say that if there was any fuel left in the tank it would have been less than 15 gallons. I put 100 gallons in there a month ago, so i thing that would have diluted any rrsidual fuel left in the tank.
Anyway, no change in rpms after todays work. Im curious as to where to start (or continue in my case). Boat runs great otherwise. If i didnt have a manual that says i should be getting 4800 rpms i wouldnt think anything was wrong. My theory is that it is a fuel problem... which brings one last question. When rebuilding the fuel pressure regulator there were 2 screws that came with the kit. I used those to close the cap on the regulator because from whae i read it is "near impossible" to squeeze down on the spring to close the cap. I replaced the diaphram but not the spring. I actually found it easy to push down and could have used the origonal screws to close it. There was resistance, but it was far from impossible. So if the spring is bad, will i still see 30psi on the rail? My theory is that the spring is weak and the regulator is sending fuel back to the vst. However, if that were the case i would think that i wouldnt be showing 30psi at wot.
Sorry for being long winded. Im trying to give as much information as possible to get a solution. Thanks in advance for the help!
1998 volvo penta 5.0gipbycce with a dp-sm 1.95:1 outdrive. The boat has been sitting for over 10 years. I spent a year trying to get this into shape to launch. Engine was frozen... patience and marvel mystery oil freed it. Replaced the starter, cap rotor, plugs, manifold, risers, bellows, fuel filter, oil, oil filter, thermostat, thermostat housing, water pump impeller, and changed gear lube. New oil pan as well as a couple other things im sure I'm forgetting.
At any rate, I got her running and splashed a month ago. Sounds good, runs good. The only thing is, i only get 3800 rpms. Im using the origonal props which are in good condition. I replaced the high pressure pump and tested fuel pressure which was 30psi. Pipe doped all fuel lines and i didnt see any air bubbles during a fuel test. I sent out the injectors to be tested, flowed and matched. I bought a rebuild kit for the tbi and cleaned and replaced everything. Cleaned out the vst and rebuilt the fuel pressure regulator. Today after puting 25 hours on it i changed the oil and filter and also the water sep fuel filter. The oil seemed dirty, which i expected since the motor was frozen. Oil wasnt burned or milky, it just seemed a bit dirty. The fuel filter had some setiment in it, but no water. I should add that there was 150 gallons of 10 year old fuel in it. I pumped all that out. I would say that if there was any fuel left in the tank it would have been less than 15 gallons. I put 100 gallons in there a month ago, so i thing that would have diluted any rrsidual fuel left in the tank.
Anyway, no change in rpms after todays work. Im curious as to where to start (or continue in my case). Boat runs great otherwise. If i didnt have a manual that says i should be getting 4800 rpms i wouldnt think anything was wrong. My theory is that it is a fuel problem... which brings one last question. When rebuilding the fuel pressure regulator there were 2 screws that came with the kit. I used those to close the cap on the regulator because from whae i read it is "near impossible" to squeeze down on the spring to close the cap. I replaced the diaphram but not the spring. I actually found it easy to push down and could have used the origonal screws to close it. There was resistance, but it was far from impossible. So if the spring is bad, will i still see 30psi on the rail? My theory is that the spring is weak and the regulator is sending fuel back to the vst. However, if that were the case i would think that i wouldnt be showing 30psi at wot.
Sorry for being long winded. Im trying to give as much information as possible to get a solution. Thanks in advance for the help!
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