extended run time stall

[Picknasty]

Happy Memorial Day everyone. The motor in question is a 1996 OMC 7.4GL 454, straight inboard no sterndrive. I have a question which I am sure is a fuel delivery issue but I'm waiting to see what you guys think. I took the boat out yesterday and the motor ran well at first. It stalled out at cruise and I figured I had some trash in my fuel/water separator, I checked and it was full of the milky, suspended water. I drained the bowl and got right back on my way. I checked it a few more times throughout the day but the bowl never gathered much trash again. When I went to go back to the launch it died and wouldn't start back up. I figured it was a fuel starvation issue so I changed the water/fuel separator and the engine mount fuel filter this morning and I am running it off an external tank with non ethanol with seafoam. after I prime the bulb it will start and then idle for a while but then cuts out like it is getting starved for fuel again. The only thing I can think of is maybe my fuel pump is going out? Any thoughts on this? Thank you in advance for the input.

 

[alldodge]

You change the filters but the carb might still be full of water

 

[Picknasty]

when the engine starts back up in the yard wouldn't that water work its way out of the carb?

 

[Picknasty]

Also when I was running a check on the fuel pump I am running, the part number is 861155-4, I see that this is a mercruiser fuel pump and it doesn't look like the one recommended by marineengine as the correct one. This is labeled as a fuel pump for V6 to smaller V8s, 5.7L max. Would it be possible I have the wrong fuel pump? I am not trying to make need for work where there isn't one but I'm really just trying to understand whats going on now.


Here is a picture of what I have

 

[alldodge]

If the pump could not pump enough volume then it would start backfiring from running lean at WOT. You have other issue currently so I do see the pump as the issue other then it may have been damaged by the water. Only way to know is to put a pressure gauge on it when running. Should be 4-7 psi at all rpms.

Could figure the water would work its way out but may still have effects and more so if it made some crud in the carb

 

[Picknasty]

I'll try a few things and report back what comes about.

 

[Picknasty]

I drained the gas out of my two 50 gallon saddle tanks, replaced the water separator filter and engine mount fuel filter. Ran fresh non-ethanol gas and replaced my fuel pump. As soon as I replaced the pump it did great, no stalling or sputtering, sounded like it should. If it is running well now should I be worried about any residual water in the carb bowl? Should I look at removing my carb and cleaning or should I be good to go from here?

 

[alldodge]

I would run it and leave the carb alone unless other run ability issues show up