1989 Bogs and shuts off after WOT

[hkeiner]

Re: 1989 Bogs and shuts off after WOT

If there's a small air leak in the suction line, a vacuum gauge won't go out of spec, but the engine won't get fuel. Bubbles will show, and pressure after the fuel pump will drop. Enough vacuum to go "out of spec" will flatten the primer bulb. Consider it a poor man's vacuum gauge.

Yes, the vacuum gauge test will detect only a RESTRICTION in the fuel line and not an AIR LEAK in the fuel line. The Mercury Service Advisory describes how to test for both of these circumstances. The first is done with the vacuum gauge and the latter is done with a clear tube inline with the fuel line and watching for air bubbles. It should also be stated that while both a RESTRICTION in the fuel line and an AIR LEAK in the fuel line can both cause fuel STARVATION, the terms are not interchangeable and the troubleshooting steps for each are different. My earlier comments regarding the use of the vacuum gauge were related to testing for fuel line RESTRICTIONS and not for AIR LEAKS. Sorry for any confusion.

Myself, I am more confident using a gauge to monitor PSI vacuum levels when testing for a fuel line RESTRICTION than looking at the squeeze bulb for changes in shape. Others with more experience troubleshooting fuel line RESTRICTION symptoms, of course, can probably do fine without the gauge.

 

[Silvertip]

Re: 1989 Bogs and shuts off after WOT

40 posts on this problem and it's still not resolved. The engine exhibits the same problem on a different tank so doesn't that pretty much define the problem? Long discussions about the issue with no "checks" being made will not fix the problem.

 

[hkeiner]

Re: 1989 Bogs and shuts off after WOT

Yes, it has become mostly an extended academic discussion on troubleshooting suspected fuel starvation. Even so, I hope it was helpful to the original poster, as well as anyone else reading this thread that has unresolved engine bog conditions and is concerned about possible fuel starvation. Perhaps there was a little too much discussion and not enough actual checking of the motor. I probably could have stopped contributing after the earlier "Amen" post. I will now.

 

[vince champion]

Re: 1989 Bogs and shuts off after WOT

ahh this thread is way too long. but anywho today i took the boat to puddingstone to do some test runs, and guess what? ITS FIXED! It runs like a champ! I thought about the previous post and maybe my cousin did do the fuel pump wrong, So i took it apart and put it togehter again. I also changed all the fuel line (inside the motor). The boat does not bog or die out anymore. I am so happy and its all cause of you guys! thanks a bunch. I apprecaite it. Hopefully this over extended thread will not go to waste and others like me will learn from it. So the things ive changed/fixed/tried on my boat are to get the problem resolved:

1. Fuel pump (twice)
2. Primer bulb and fuel line
3. Fuel line (inside the motor)
4. Fuel filter
5. Running boat on external fuel tank
6. Added a fuel/water seperater
7. Mercury quickclean Fuel treatment (suppose to help the carb clean the needle and seat)

I have one last question tho, or maybe i should start another thread since this is way too long, anyways I ran my boat for the first 4 hours fine, but as i was leaving i wanted to do a few laps and this beeping noise came from the throttle controller. Now i know it has a meaning for different beeps. Just i dont know which is which. The beep goes like "beep beep beep beep beep beep beep". As long as have it in gear it will make that noise. So is this a over heating or oil problem? Right when i fixed my boat another problem comes up. But hope someone can help me with this and i appreciate everyones help! Thank you again vince.

 

[gss036]

Re: 1989 Bogs and shuts off after WOT

First off, great to hear that you have solved your fuel problem. A good move changing the oil/fuel lines on the engine, they do get brittle and fail. There is no alarm for that and you will cook an engine if they were to fail.
As for the beep-beep, that normally is an oil problem. You need to run on prex-mix until you solve it. The cap on the oil tank on the engine is a good palce to check. Follow the two electrical lines along the port sidd eof the engine and disconnect the blue one, this might stop the beeping, if that dooes it, then determine if the sender in the cap is bad. It has a magnetic pick up indicating low oil. On your 89, those have been trouble free. Some of the later ones have a magnet glued on the bottom and it falls off.
The other area is the motion sensor for the oil pump. You need to determine if the pump is working or if there is a problem in the sensor. Again follow the electrical lines to the starboard side of the engine and disconnect the ground and see if that stops the beeping.
If that doesn't help, I would suggest you post a new thread.

 

[swamprunner]

Re: 1989 Bogs and shuts off after WOT

check the fuel pickup in the tank. that could be clogged or partially blocked by something. it could be an original piece and have restricted and hardened from the fuel. i have also heard of the pickup tube being too long or not having the little filter on the end. if the tube is too long or doesnt have that little filter on the end it will suck to the bottom or side of your fuel tank and that will cause all these fuel starving symptons you've been having. because once you shut it down or back off the throttle, there is less demand for fuel and thus less suction and the hose will move slightly. then once you are back up to WOT it sucks back to the tank. if that is the case then puttin on one of those end filters will work. (they look like the little rock air bubblers you see on the end of the air hose in a fish tank) OR a simple cut will do. dont cut off alot of hose because remember - it has to reach the fuel to pick it up. but a simple biased (angled) cut slightly above the end of the tube will do the trick. the angle provides for a slightly larger intake opening (which wont harm anything) and it also keeps it from sucking against the tank.

 

[vince champion]

Re: 1989 Bogs and shuts off after WOT

thx for your reply swamprunner but the problem is fixed already. lol

 

[DamianJP]

Re: 1989 Bogs and shuts off after WOT

Might sound small but did you check the fuel line from the fuel tank to water sep. Mine was rough looking and even no leak at idle. But My Priming Bulb wouldn't stay hard and after high speed to WOT sometimes I had that bog down. I know you just added the water sep. so the line is prolly new & snug. My guess is a air leak in the one of the fuel lines or Carb Float levels But Im not a mechanic. Hope this helps

Damian