Starting the boat when flooded (Mercruiser 120)

[Nijkampr]

Hi guys,

We took the boat out to a nearby lake earlier this week. On Monday, we trailered the boat to the cabin and dropped it into the water a few hours later. The boat ran very strong for hours. We had to put the boat on the trailer overnight because we didn't have a dock.

The next day we launch the boat and the engine sputtered and died. We couldn't keep it running. I could get it to fire / sort of run at WOT. At WOT, the engine was basically at idle speed; stammering badly. When I pulled back on the throttle, it would stall. I could tell when the power jets (not sure what they're called) would squirt fuel into the carb when I pushed the throttle open. I don't believe this is a fuel starvation problem.

I've had problems in the past with the points slipping closed and I assumed that this happened again but they appear to be gapped correctly. But I do remember testing the plugs in the past and thinking there was a weak spark. It is very difficult to see the spark.

This is why I want to install the electronic ignition and rule that much out of the equation.

But I thought I would post the symptoms anyhow and see if there were any other thoughts out there. I believe I ran into a case of a flooded motor with a weak spark that was not able to clear itself out. I know the idle mixture screws are set a bit rich and that combined with the choke being on could add up to a flooded engine (my thoughts anyhow).

I thought that you could clear a flooded Mercruiser out by turning it over at WOT. Is this the correct procedure?

Slightly off topic... I did recently install an inline fuel filter and I've read posts about that being a bad idea. Should I remove it? I don't believe this is the problem; I'm just curious.

Thanks guys.
Rob

 

[Nijkampr]

Re: Starting the boat when flooded (Mercruiser 120)

In the interest of safety, should I remove the inline fuel filter I recently installed? It is made of glass.

 

[Another retired guy]

Re: Starting the boat when flooded (Mercruiser 120)

It sounds like a fuel starvation issue. Have you checked that new filter to see if it's plugged? Also check the other filters. I don't see why an inline filter would be a bad idea? Glass is subject to breaking if knocked, but if it's positioned in the clear where it can't be hit by anything, I wouldn't be concerned.
And yes, the correct procedure for clearing a flooded engine is to crank it with throttle fully open - don't pump the throttle and don't crank for more than 10 seconds.

 

[Silvertip]

Re: Starting the boat when flooded (Mercruiser 120)

Why would you install electronic ignition in hopes it fixes other problems? You said the choke is on. On a warm engine, why is it on? Obviously if the choke is on a warm engine will tend to flood. You said the points "appear" to be gapped correctly. If you have trouble with the point gap slipping, fix the cause. The only reason this can happen is if the mounting screw is stripped. Fix the problem. You also said the mixture screws are set rich. Why? Set them correctly. You apparently have a series of problems that electronic ignition alone will not cure.

 

[Nijkampr]

Re: Starting the boat when flooded (Mercruiser 120)

Why would you install electronic ignition in hopes it fixes other problems? You said the choke is on. On a warm engine, why is it on? Obviously if the choke is on a warm engine will tend to flood. You said the points "appear" to be gapped correctly. If you have trouble with the point gap slipping, fix the cause. The only reason this can happen is if the mounting screw is stripped. Fix the problem. You also said the mixture screws are set rich. Why? Set them correctly. You apparently have a series of problems that electronic ignition alone will not cure.

I wanted to install an electronic ignition anyhow to help address my weak spark issue (see first post). But I'm going to hold off for now until the boat is running properly again (assuming the problem was related to flooding).
I didn't say the choke was on when the engine was warm. The choke was on when the engine was cold the following day when we launched the boat again (see first post). I believe my idle screws are set a bit rich. I only say that because the boat sometimes stutters when applying throttle quickly after it has been idling for a bit. But this could also be related to my weak spark issue I suppose. This is my first year with my first boat and I'm trying to learn on the fly as I go. Please bear with me as I am not a career mechanic but I am somewhat technically inclined.

 

[Bondo]

Re: Starting the boat when flooded (Mercruiser 120)

I wanted to install an electronic ignition anyhow to help address my weak spark issue (see first post). But I'm going to hold off for now until the boat is running properly again (assuming the problem was related to flooding).
I didn't say the choke was on when the engine was warm. The choke was on when the engine was cold the following day when we launched the boat again (see first post). I believe my idle screws are set a bit rich. I only say that because the boat sometimes stutters when applying throttle quickly after it has been idling for a bit. But this could also be related to my weak spark issue I suppose. This is my first year with my first boat and I'm trying to learn on the fly as I go. Please bear with me as I am not a career mechanic but I am somewhat technically inclined.

Ayuh,... Steal an emery board from yer Love, 'n go file yer points, then reset 'em,...

If ya get a Strong spark, replace the points, 'n condenser,...

There's a thread on Points ignition, up in the Adults Only section, up near the top of this forum,...

 

[Nijkampr]

Re: Starting the boat when flooded (Mercruiser 120)

Ayuh,... Steal an emery board from yer Love, 'n go file yer points, then reset 'em,...

If ya get a Strong spark, replace the points, 'n condenser,...

There's a thread on Points ignition, up in the Adults Only section, up near the top of this forum,...

The points were replaced a month ago. Could they be done / carbon'd up already? I will take a look.