Hi all, I've been reading these forums for a few months now. Figured I'd finally make an account as I'm stumped!
The boat is a 1986 Bayliner Capri open bow, with a Force 125 2-cycle engine. I'll start by listing the things I've done so far to try to solve my issues:
When I first bought the boat, I was losing fuel extremely fast, couldn't idle, and eventually started losing power / cutting out at full throttle.
Compression test - good on all cylinders
Carburetors professionally rebuilt and cleaned - fixed nothing (engine was not run until the next 2 things were done)
Every inch of fuel line on the boat replaced - fixed nothing
Installed a water/fuel separator - preventative - fixed nothing
Linkage professionally adjusted - fixed nothing
Replaced fuel pump diaphragm - Solved all problems! Boat idled great, full power, smooth acceleration, nirvana achieved, etc.
Unfortunately, this was for about 3 hours of run time, over 2 outings. Then I started to have an intermittent problem. It would run great for a few minutes then lose power and die. Then it was impossible to start for 5-10 minutes, after which time it would run perfect for a few minutes again. Over a few cycles of this while trying to diagnose, the problem would last longer, and come on quicker. It seemed electrical, I pulled the boat home.
At home I found I had no spark on cylinder 3. Hooked my battery up to a trickle charger for the first time (just got this boat late last year) and let it sit for a week until I had time to work on it again. I switched the wiring so that the CDI modules would be swapped, hoping that my no-spark cylinder would follow. Even better - or worse in my opinion, I had spark on all 4! I switched the wiring back to its original state and still had spark on all 4 cylinders.
Cautiously optimistic I took it to the lake, as any boat owner knows, if you want to re-create your problem - just simply try to use the boat. It fired up great, idled fine. I let it warm up and pulled away from the dock. It picked up well, and was running fine and I was doing short full throttle runs - not even reaching full speed.On my 3rd full throttle run I lost power. The engine didn't die, but it bogged down to idle basically. After idling for a minute, it would have power again. Only for a few seconds before bogging back out. So, this sounds like another fuel problem to me. This is where I'm at now.
my questions:
1) Is it possible for my battery to have a low enough charge to make me lose spark to a cylinder, while still being able to turn the motor over? It's the only thing I can think of as to why the spark came back, since I charged the battery.
2) If it's a fuel problem, do you think it could be the fuel reeds? I just found out about these recently, and it sounds like they operate similarly to the fuel pump diaphragm, so perhaps the same thing that damaged the original diaphragm could have damaged the reeds?
3) Also fuel problem related. I've been told I should clean the fuel tank out. I bought some super powerful magnets to push around in there with a coat hanger or something, but it makes me anxious. Not only could one fall off, but it could break loose sediment/things that wouldn't have been a problem before. Is this a good idea?
4) If the electrical problem is not explained by my theory in question 1, and I can only seem to get it to act up during a full throttle run, how in the world could I test what cylinder isn't getting spark in order to diagnose it?
I appreciate you taking the time to read this. I feel like I'm running out of possible causes to this problem, which must mean it's getting close to finally functioning properly!
The boat is a 1986 Bayliner Capri open bow, with a Force 125 2-cycle engine. I'll start by listing the things I've done so far to try to solve my issues:
When I first bought the boat, I was losing fuel extremely fast, couldn't idle, and eventually started losing power / cutting out at full throttle.
Compression test - good on all cylinders
Carburetors professionally rebuilt and cleaned - fixed nothing (engine was not run until the next 2 things were done)
Every inch of fuel line on the boat replaced - fixed nothing
Installed a water/fuel separator - preventative - fixed nothing
Linkage professionally adjusted - fixed nothing
Replaced fuel pump diaphragm - Solved all problems! Boat idled great, full power, smooth acceleration, nirvana achieved, etc.
Unfortunately, this was for about 3 hours of run time, over 2 outings. Then I started to have an intermittent problem. It would run great for a few minutes then lose power and die. Then it was impossible to start for 5-10 minutes, after which time it would run perfect for a few minutes again. Over a few cycles of this while trying to diagnose, the problem would last longer, and come on quicker. It seemed electrical, I pulled the boat home.
At home I found I had no spark on cylinder 3. Hooked my battery up to a trickle charger for the first time (just got this boat late last year) and let it sit for a week until I had time to work on it again. I switched the wiring so that the CDI modules would be swapped, hoping that my no-spark cylinder would follow. Even better - or worse in my opinion, I had spark on all 4! I switched the wiring back to its original state and still had spark on all 4 cylinders.
Cautiously optimistic I took it to the lake, as any boat owner knows, if you want to re-create your problem - just simply try to use the boat. It fired up great, idled fine. I let it warm up and pulled away from the dock. It picked up well, and was running fine and I was doing short full throttle runs - not even reaching full speed.On my 3rd full throttle run I lost power. The engine didn't die, but it bogged down to idle basically. After idling for a minute, it would have power again. Only for a few seconds before bogging back out. So, this sounds like another fuel problem to me. This is where I'm at now.
my questions:
1) Is it possible for my battery to have a low enough charge to make me lose spark to a cylinder, while still being able to turn the motor over? It's the only thing I can think of as to why the spark came back, since I charged the battery.
2) If it's a fuel problem, do you think it could be the fuel reeds? I just found out about these recently, and it sounds like they operate similarly to the fuel pump diaphragm, so perhaps the same thing that damaged the original diaphragm could have damaged the reeds?
3) Also fuel problem related. I've been told I should clean the fuel tank out. I bought some super powerful magnets to push around in there with a coat hanger or something, but it makes me anxious. Not only could one fall off, but it could break loose sediment/things that wouldn't have been a problem before. Is this a good idea?
4) If the electrical problem is not explained by my theory in question 1, and I can only seem to get it to act up during a full throttle run, how in the world could I test what cylinder isn't getting spark in order to diagnose it?
I appreciate you taking the time to read this. I feel like I'm running out of possible causes to this problem, which must mean it's getting close to finally functioning properly!