97 250HP Offshore (EFI) has no power

[gantone1]

Motor was running fine last week, Saturday it seemed to smoke more than usual and when I left dock and tried to accelerate it had no power. I could go no faster than idle speed. First thought was one of my ignition banks failed and I was running on 3 cylinders. But checked the plugs and all 6 were rich looking and all looked the same.

Where should I start troubleshooting what I think is a too rich condition, or am I jumping to conclusions?

Thanks for any help!

1997 Mercury 250HP Offshore (EFI)

 

[Faztbullet]

Re: 97 250HP Offshore (EFI) has no power

Check to see if your missing spark on one bank as some 97 models had a shift interrupter switch that kills oneside when shifting....

 

[gantone1]

Re: 97 250HP Offshore (EFI) has no power

That seemed like a good (and potentially easy) cause, but I am getting a spark in all 6 cylinders. I checked it in neutral and while it was in gear. It seems unusually rich, smoking a lot and the plugs are dark and wet, almost to the point of being fouled. All 6 plugs look the same.

I checked for spark by putting my my timing light on each spark plug wire, I assume that is a valid test, please let me know if that is not.

Thanks for any help you can provide!

 

[paulsboat]

Re: 97 250HP Offshore (EFI) has no power

I have the same motors . Put a fuel pressure test on the test nipple ( like a tire fill valve ) at the top of the fuel tank for the injection. Mine read 54 psi or more and should have been 34 -38 . Took off regulator sprayed cleaner in it . Took out really small fuel screen under regulator and cleaned . Out back together and pressure was 36 . Motor ran good. No smoke ect. No parts needed . Small o ring is the seal.If your pressure is good then it is something else.

 

[gantone1]

Re: 97 250HP Offshore (EFI) has no power

I just pressure tested and got 37 lbs at the nipple, this was at idle.

Does correct pressure here mean I do not likely have a fuel problem?