This is a history of the post on another site
I have a 2006 F150 with 550 hours on it. I bought it used and found out after I bought it that it will only tach to 5400 rpm's. I have cleened the injectors, changed plugs, changed fuel filters, run yamaha combustion chamber cleaner throug it, run a leakdown test three time throught the cleaning process and checked the valve lash. # 1&4 cilinders have 4 lbs of leakdown at 90 lbs supply #2 has 20 lbs and #3 has 30 lbs. I have been told to shock it with yamaha ring free 32 oz in a small gas can. I think the problem is in hte valves but not positive. I am passing air from #3 to #1 cilinder when I run the leakdown test. I don't know where the air for #2 cilinder is going I didn't pull the intake off after I ran the boat last.
The prop is a 14.75x16 pitch which is about right for the boat by talking to other people that have the same rig. No I'm reveing it up in neutral the 5400 is and the motor is trimmed out properly. Not my first boat just a new one to me. If I'm loosing compression I won't be able to get full RPM's. I don't want to run it that hard unless I need it but I can't get the best fuel milage if the motor is not able to run at peek performance. I could have a bad or carboned valve or even a head gasket problem and I don't want to go on a long fishing tirp with unknown problems.
I went to a prop builder here and discussed what prop to run. We changed a prop that I had heavy cup in with a 17 pitch to a lighter cup and a true 16 pitch and ballanced it. This is what the prop wizard said to run also. At this time I don't think its the prop. I am going to do a compression test tonight to see if there is a difference there. Leakdown test tells you if your valves or rings are not sealing off on the compression stroke. Basic test that any shop will do first to see what is going on in the engin.
I have a 2006 F150 with 550 hours on it. I bought it used and found out after I bought it that it will only tach to 5400 rpm's. I have cleened the injectors, changed plugs, changed fuel filters, run yamaha combustion chamber cleaner throug it, run a leakdown test three time throught the cleaning process and checked the valve lash. # 1&4 cilinders have 4 lbs of leakdown at 90 lbs supply #2 has 20 lbs and #3 has 30 lbs. I have been told to shock it with yamaha ring free 32 oz in a small gas can. I think the problem is in hte valves but not positive. I am passing air from #3 to #1 cilinder when I run the leakdown test. I don't know where the air for #2 cilinder is going I didn't pull the intake off after I ran the boat last.
The prop is a 14.75x16 pitch which is about right for the boat by talking to other people that have the same rig. No I'm reveing it up in neutral the 5400 is and the motor is trimmed out properly. Not my first boat just a new one to me. If I'm loosing compression I won't be able to get full RPM's. I don't want to run it that hard unless I need it but I can't get the best fuel milage if the motor is not able to run at peek performance. I could have a bad or carboned valve or even a head gasket problem and I don't want to go on a long fishing tirp with unknown problems.
I went to a prop builder here and discussed what prop to run. We changed a prop that I had heavy cup in with a 17 pitch to a lighter cup and a true 16 pitch and ballanced it. This is what the prop wizard said to run also. At this time I don't think its the prop. I am going to do a compression test tonight to see if there is a difference there. Leakdown test tells you if your valves or rings are not sealing off on the compression stroke. Basic test that any shop will do first to see what is going on in the engin.