7.4 GI power issues

I have a 1996 7.4 GI. I have been having a problem with the motor not getting to max rpm's. I most recently attained only 3800 r's. This problem has been going on for some time but was still able to get on plane and use the boat but not to it's full potential. 3 days ago, went out on the boat, got on plane and ran it for about 45 minutes. Stopped for 30 minutes and when restarted, tried to get on plane but the motor coughed and lost power (still running) then started a poping noise in the motor. Dumped the fuel filter and replaced, without filling it up again and then wouldn't restart at all thus ending in being towed in. I realized now I probably vapor locked the motor because of this. The next morning, started the motor, it got up on plane and ran ok like the previous day. let it sit for a minute and then the problems came back. It started but lost power and the motor popped again. I'm looking for suggestions on my immediate problem and then also how to get the max rpm's from this motor. thanks for any help you might give me. Very frustrating.

Hey, Did you ever figure out your issues?
I have a 99 Volvo 7.4Gi with similar issues. I'm not getting the the sputtering and coughing problem but I'm no longer achieving the max RPM that I use to be able to get. The engine seams to be lacking power from about 2500 - 3100rpm. It barly will get on plane, but once it surpasses 3100rpm it seams ok, but maxes out about 3800 - 4000rpm... It just doesn't seem to be the same and lack's power that it should have. My mechanic has been over the engine top to bottom and can only see that the timing does not appear to be advancing as the RPM increases. we dont know though, there are no error or fault codes and the knock sensors are also not registering any problems. I'm thinking maybe a ECU issue with controlling the timing but really don’t know. Let me know how you made out or if anyone else out there as some suggested it would be greatly appreciated!
Thanks in advance!

Do you have any answers to share on the problems you were having at 3000 RPMs and above? I see that these issues were posted in 2011.
i am having similar issues now with 1995 Volvo Penta 7.4 Gi engine and am stumped after changing many things - high pressure fuel pump, plugs, wires, an entire distributor, coil and can’t figure it out. Im wondering now if it is ECM?
Thanks. SG

Sgonzo63 said:

Do you have any answers to share on the problems you were having at 3000 RPMs and above? I see that these issues were posted in 2011.
i am having similar issues now with 1995 Volvo Penta 7.4 Gi engine and am stumped after changing many things - high pressure fuel pump, plugs, wires, an entire distributor, coil and can’t figure it out. Im wondering now if it is ECM?
Thanks. SG

Click to expand...

I am also interested in if this has been solved. I started a thread here a few days ago about a similar issue with an 8.1 Volvo but haven’t gotten any feedback yet on my post.

When looking at old posts, always check the "post count" on the upper right. If its a low number, its likely the poster posted and ran...and is likely no longer following this forum,

First question... while you owned this boat did it ever rev to rated Wide Open throttle RPM ???