Submerged Mercuiser Now Needs Different Style Plugs

[b0mbtrack]

Mercruiser ow356239, MPI Bravo III.

The engine went under and Before I started it up I got all the water out of the oil pan and all the water out of the cylinders (rag and thumb over s/p hole while cranking). I changed the oil and filter then went to start it up for the first time since going under and it wouldn't start. I heard that a hydro-locked engine could hurt the plugs and when I took them out they were soaked with fuel. I didn't have the right plugs (AC 41-932) so I temporarily put in another plug (nhk bpr6efs) so that I could finish the oil change and do another. The engine started right up and sounded good with these other plugs so I did the oil ect.... I finally got the correct plugs and put them in but when I try to start it the engine does the same thing that it did to begin with, by that I mean the plugs load up with fuel. Should I just go ahead and use these ngk plugs that I put in or is there something else I should do?

 

[Bondo]

Re: Submerged Mercuiser Now Needs Different Style Plugs

I finally got the correct plugs and put them in but when I try to start it the engine does the same thing that it did to begin with, by that I mean the plugs load up with fuel.

Ayuh,... That sounds like a Fuel delivery issue, not the brand of sparkplugs...

 

[b0mbtrack]

Re: Submerged Mercuiser Now Needs Different Style Plugs

It is MPI and I do have a computer to test with but I honestly wouldn't know what to look for in the computer.

 

[zbnutcase]

Re: Submerged Mercuiser Now Needs Different Style Plugs

I agree the brand of plugs wouldn't cause your problem. That said, I prefer NGK plugs personally. 'nutcase

 

[Bt Doctur]

Re: Submerged Mercuiser Now Needs Different Style Plugs

Any chance the water went over the module or computer box?

 

[b0mbtrack]

Re: Submerged Mercuiser Now Needs Different Style Plugs

I probably should have said that this is salt water also not that it makes a difference with anything so far but just incase it comes up.

I prefer NGK too and I agree that the plugs aren't the cause of the problem so I'll try and figure out what is really going on. There is a chance that the water made it to the computer but I really don't see any corrosion that far up the engine, I guess what I'll do is disconnect the computer and check the plug posts for white corrosion just to be sure. Is there anyway to test the fuel output with the DDT computer?

 

[b0mbtrack]

Re: Submerged Mercuiser Now Needs Different Style Plugs

I looked in the service manual and it says that a bad cap and rotor could cause poor fuel economy so i'll probably look under the cap real quick to see how it looks but I doubt that will be the problem.
If nothing is there I'll try to diagnose with the DDT.
If I really can't find anything would anyone know if it is safe to use these other plugs since they seem able to burn the fuel where the others don't?

 

[Gary H NC]

Re: Submerged Mercuiser Now Needs Different Style Plugs

The engine was submerged and you have not looked under the dist. cap??
Good place to start....

 

[HT32BSX115]

Re: Submerged Mercuiser Now Needs Different Style Plugs

I probably should have said that this is salt water also not that it makes a difference with anything so far but just incase it comes up.

Howdy,


Well, yes it makes a difference! Fresh water is not a very good conductor of electricity. SALT WATER IS!


You need to take every connector and everything else electrical on the engine apart unless it's sealed, and flush it well with fresh water. Then ensure that each is completely dry before you even try applying power or running the engine!


Good luck,


Rick

 

[Ohioriver]

Re: Submerged Mercuiser Now Needs Different Style Plugs

"quote" The engine started right up and sounded good with these other plugs so I did the oil ect.... If it runs fine on the NKG plugs, but won't run on the AC plugs, it sounds like a fouled set of plugs, or some minor issue. My Kohler genset runs best on NKG plugs, it doesn't like AC or Champion as well, they tend to foul out.