Mercruiser Issue's

[Wylone1]

I have a 1999 Bayliner Capri, with a 3.0 Mercruiser Sterndrive. The boat has less than 100 hrs, and has been well maintained. At the end of May, I had the carb rebuilt. Shortly after, the motor would quit on plane above 2000 rpm. I thought they messed up the carb rebuild and I brought it back. They took it apart, tested it, rebuilt it again (all at no cost to me) and bench tested it. They assured me the carb was fine. I changed the anti syphon valve, checked the fuel filters, checked for contaminated fuel, and the ignition system. The boat idles fine, and runs well out of the water (on a lift, with water supplied to the pick ups). But, in the water, the engine quits after about 10 seconds running at 2000 rpm or more. Any thoughts would be appreciated.

 

[spannerman]

First I would check the fuel pump is delivering enough fuel, you can look into the carb venturi and see fuel spraying in so check if this is still happening when it dies out, if it is then fuel delivery would seem to be fine, if the fuel dries up followed by loss of power then you need a new pump.
If fuel is OK when it quits then its going to be an ignition problem, I have changed several ignition triggers on these engines, its a coil in the distrubutor and they break down when the engine warms up and then work again when its cooled off.
When it stops you need to check if there is a spark when you crank the motor, the rev counter should fail also as this gets its signal from the coil negative pole which won't be switched on and off if the trigger fails.

 

[dpb]

There may be a filter that you may have missed at the fuel pick up in the tank, or in a fitting on the outside face of the tank. If partially blocked can allow enough fuel for low revs but not for high.

 

[Wylone1]

I changed all the ignition components. Also, when the engine died, I checked the carb, and operated the throttle. The fuel streamed in fine. The only filter I haven't checked is the one in the tank, attached to the pick up line. The one referred to as the "sock filter". If that's fine, I don't know what else to do. Someone mentioned checking the cylinder compression; however, I don't think that's the issue. I'm wondering when they rebuilt the carb, if they messed up the float some how, and the carb is running out of fuel. I brought the carb back into the shop and they checked and rechecked it again. They even rebuilt it a second time (at no charge) and bench tested it. They assured me it's fine. But, I've heard that before.

 

[Assassin]

The in tank filter may well be the problem, and it is a problem i have encountered on many 4X4's, basically if they deteriorate and split they get sucked over the end of the pick up pipe and act like a flap valve and restrict fuel flow.

 

[Denis O]

My 3.0 played up similarly last month and it turned out to be the anti-syphon valve as the pipe comes out of the tank.

I see you've changed yours. Did you replace or remove the ball and spring?

 

[Wylone1]

I installed a new anti syphon valve complete with new ball and spring. I thought that was the issue also. I'm following the fuel system from top to bottom. The last thing to check is the pick up in the tank. If it's not that, then I have no Idea. I've checked everything else.

 

[Wylone1]

I raised the pick-up line from the tank but, was unable to remove it. Seems to be stuck on something. The sock filter maybe?