1972 F-36 port motor problems
Posted: Sat Dec 23, 2017 9:49 am
I have posted about what I believe are fuel problems affecting our port motor. The boat is powered with Marine Power 454's. About 2 years ago I began have some intermittent stalling problems typically after a short shut down and then restarting. Initially the boat would stall and shut down. After restarting it would run fine. Then the problem started occurring more frequently after shutting down for a half hour or so and when I'd try to restart the motor it would not start. For a while once it cooled down the motor would start again and run fine. The problem got worse over time to the point the motor would not start until we'd get back to the dock or sometimes it would not restart until the next morning.
My mechanic initially suspected an electrical issue and we replaced the distributor. That didn't fix the problem. Then we started looking at the fuel system and found when the motor was hot no fuel was getting past the primer pump which had not been working for a couple years. My mechanic bi-passed the priming pump and that fixed the starting problem when the boat was hot but a new problem then started happening. Now when underway and throttling up or down in the 900 to 1100 rpm range the motor stalls and the rpms drop to zero and they jump back up. This happens repeatedly until I power down a couple hundred rpms, or powering up a couple hundred RPMs when powering up. The boat runs great outside of 300 RMP range when powering up or down. The problem only happens in the same 300 or so RPM range. The boat runs great at higher and lower speeds. Yesterday the same problem happened at the dock while we were not underway. After revving the boat up and down it would run rough and stall. Restart and the problem would repeat. This time my mechanic was on the boat to witness the problem under power and at the dock. We just rebuilt the carbuerator thinking that would finally fix the problem but it did not.
My mechanic is convinced there is still a fuel problem. Could running the boat with the priming pump bipassed becausing the RPM and stalling problem? This problem newest problem started after the priming pump was bipassed. When we were checking the fuel system a few months ago we pulled the motors fuel seperator filter and there was a little water and debris in the fuel. Could this be the problem? If it is, is there something that can remove the water and any debris that may be in the port fuel tanks? Should the fuel be polished to remove the water and sediment?
My new concern now is the port fuel tanks. If there's sediment and rust in the tanks should the tanks be replaced? I'm sure replacing the fuel tanks will be very expensive since the motor will need to be removed to replace the port motor saddle tank and the rear transom deck will need to be removed to replace the stern reserve tank. Has anyone replaced their fuel tanks? If so how much did it cost?
Any ideas on what may be causing the problem and possible solution would be greatly appreciated. This problem has been happenning for over two years in varying degrees. I really want to get it fixed once and for all so I can confidenatlly run the motor. Right now its running very erratically and you never know what's going to happen next.
Thanks,
Frank
Plan B
1972 F-36
My mechanic initially suspected an electrical issue and we replaced the distributor. That didn't fix the problem. Then we started looking at the fuel system and found when the motor was hot no fuel was getting past the primer pump which had not been working for a couple years. My mechanic bi-passed the priming pump and that fixed the starting problem when the boat was hot but a new problem then started happening. Now when underway and throttling up or down in the 900 to 1100 rpm range the motor stalls and the rpms drop to zero and they jump back up. This happens repeatedly until I power down a couple hundred rpms, or powering up a couple hundred RPMs when powering up. The boat runs great outside of 300 RMP range when powering up or down. The problem only happens in the same 300 or so RPM range. The boat runs great at higher and lower speeds. Yesterday the same problem happened at the dock while we were not underway. After revving the boat up and down it would run rough and stall. Restart and the problem would repeat. This time my mechanic was on the boat to witness the problem under power and at the dock. We just rebuilt the carbuerator thinking that would finally fix the problem but it did not.
My mechanic is convinced there is still a fuel problem. Could running the boat with the priming pump bipassed becausing the RPM and stalling problem? This problem newest problem started after the priming pump was bipassed. When we were checking the fuel system a few months ago we pulled the motors fuel seperator filter and there was a little water and debris in the fuel. Could this be the problem? If it is, is there something that can remove the water and any debris that may be in the port fuel tanks? Should the fuel be polished to remove the water and sediment?
My new concern now is the port fuel tanks. If there's sediment and rust in the tanks should the tanks be replaced? I'm sure replacing the fuel tanks will be very expensive since the motor will need to be removed to replace the port motor saddle tank and the rear transom deck will need to be removed to replace the stern reserve tank. Has anyone replaced their fuel tanks? If so how much did it cost?
Any ideas on what may be causing the problem and possible solution would be greatly appreciated. This problem has been happenning for over two years in varying degrees. I really want to get it fixed once and for all so I can confidenatlly run the motor. Right now its running very erratically and you never know what's going to happen next.
Thanks,
Frank
Plan B
1972 F-36