gage_keeble
Cadet
- Joined
- Jul 19, 2021
- Messages
- 10
Hi there,
I have a 1992 Wellcraft Corsair with two Mercruiser Bluewater 7.4L. I have been in the process of tuning them up these past couple weeks and getting them ready for summer. Both engines ran OK last year, but this year they are struggling to stay running. So far I have adjusted the ignition timing and both of them are dialed in to 8 degrees BTDC as per spec. But, even with all this done, the engines each have their own quirks. The port side will fire up and idle, but when revved up quickly it will backfire. When underway last season, the engine would not rev all the way up to match the starboard side and would sometimes die on plane. As for the starboard, it will sporadically idle, bouncing from 1000-2000RPM and needs throttle input to stay running until it is completely warmed up. Both show a manifold vacuum reading of 12-14 and vibrate between the two readings.
I can't tune the 2-year old, new, Quadrajet carbs on both engines as they don't respond to the screw turns and will suddenly die if the screws are turned to far. Supposedly the engines were semi-recently rebuilt, but are somewhat old in appearance. I haven't checked for any vacuum leaks yet, but will do so as soon as the weather clears up. The water/fuel filters are only 2-years old, and I will check those as well.
At this point I am hoping someone can point me in the right direction of what kind of problem this sounds like or what I should look for. Any help is greatly appreciated and thanks for your time!
I have a 1992 Wellcraft Corsair with two Mercruiser Bluewater 7.4L. I have been in the process of tuning them up these past couple weeks and getting them ready for summer. Both engines ran OK last year, but this year they are struggling to stay running. So far I have adjusted the ignition timing and both of them are dialed in to 8 degrees BTDC as per spec. But, even with all this done, the engines each have their own quirks. The port side will fire up and idle, but when revved up quickly it will backfire. When underway last season, the engine would not rev all the way up to match the starboard side and would sometimes die on plane. As for the starboard, it will sporadically idle, bouncing from 1000-2000RPM and needs throttle input to stay running until it is completely warmed up. Both show a manifold vacuum reading of 12-14 and vibrate between the two readings.
I can't tune the 2-year old, new, Quadrajet carbs on both engines as they don't respond to the screw turns and will suddenly die if the screws are turned to far. Supposedly the engines were semi-recently rebuilt, but are somewhat old in appearance. I haven't checked for any vacuum leaks yet, but will do so as soon as the weather clears up. The water/fuel filters are only 2-years old, and I will check those as well.
At this point I am hoping someone can point me in the right direction of what kind of problem this sounds like or what I should look for. Any help is greatly appreciated and thanks for your time!
