I have had an issue going on for 6 weeks that is driving me crazy. It started right after I changed my throttle positioning sensor and I changed wheels from a 22 square to a 24x21. The boat runs great for almost exactly 15 gallons, and then takes RPMs away. I have a 6081 John Deere 6 cyl 8.1 liter. I cruise at 2200 rpm and it would take me back to 2000. After that happens, when I push the throttle forward it takes away more until I pull it back to the "sweet spot". After I sat on the dive spot for a couple hours, it would go back to normal for another 15 gallons. It started on the way to Wrightsville in August. I changed every filter on the engine. No effect.
When I got to Morehead, we put a vacuum gauge on the Racor. It would read 6-7 inches on the port side, a little less on the starboard tank. To my mechanic and I it seemed there was a restriction from the racor back to the tanks. We pulled the floats out expecting to find gunk in the tanks. The fuel was sparkling clean. I isolated every hose on the boat pulling from a bucket of fuel. I found two lines to have restrictions. We replaced every line, rebuilt the changeover valves, and the racor filter. The restrictions still remained, so we decided it was the pick ups. We ordered new pick ups, deciding we would have to bend the existing one to get them out (or cut the deck). I didn't have time to install them before I went back down to Wrightsville last week. Still convinced it was the pick ups, and being very frustrated..while I was there I pulled the float out of the port tank and fabricated a temporary pick up to bypass the existing one. I thought that would solve my problem until I could install the permanent pick ups. No change, did exactly the same thing.
Any ideas?
My mechanic refuses to accept any thing other than a fuel restriction. I am not convinced. One noteworthy thing is that it is way worse when I have a heavy load, especially in a following sea. On the way home yesterday with just me she ran great for about 25 gallons, then I could feel fluctuations in the rpms but never really lost them for long and maintained speed.
I am beginning to think it has to have something to do with the electronic throttle control and maybe spinning a larger wheel. But why does she run great for the 1st 15 gallons?
I am freaking pulling my hair out over this.
---------- Post added October 23rd, 2013 at 11:46 AM ----------
7 views but no thoughts? Come on fellas, help a guy out.
When I got to Morehead, we put a vacuum gauge on the Racor. It would read 6-7 inches on the port side, a little less on the starboard tank. To my mechanic and I it seemed there was a restriction from the racor back to the tanks. We pulled the floats out expecting to find gunk in the tanks. The fuel was sparkling clean. I isolated every hose on the boat pulling from a bucket of fuel. I found two lines to have restrictions. We replaced every line, rebuilt the changeover valves, and the racor filter. The restrictions still remained, so we decided it was the pick ups. We ordered new pick ups, deciding we would have to bend the existing one to get them out (or cut the deck). I didn't have time to install them before I went back down to Wrightsville last week. Still convinced it was the pick ups, and being very frustrated..while I was there I pulled the float out of the port tank and fabricated a temporary pick up to bypass the existing one. I thought that would solve my problem until I could install the permanent pick ups. No change, did exactly the same thing.
Any ideas?
My mechanic refuses to accept any thing other than a fuel restriction. I am not convinced. One noteworthy thing is that it is way worse when I have a heavy load, especially in a following sea. On the way home yesterday with just me she ran great for about 25 gallons, then I could feel fluctuations in the rpms but never really lost them for long and maintained speed.
I am beginning to think it has to have something to do with the electronic throttle control and maybe spinning a larger wheel. But why does she run great for the 1st 15 gallons?
I am freaking pulling my hair out over this.
---------- Post added October 23rd, 2013 at 11:46 AM ----------
7 views but no thoughts? Come on fellas, help a guy out.