Mercury 1998 150 V6 efi 2 stroke issue

[Josh13250]

Hi all, i have a Mercury 1998 150 V6 efi 2 stroke, it usually starts well and runs great on the first start when its cold, once it’s turned off and sits a bit it starts but only 3 cylinders seem to be firing and it doesn’t get any better. I changed the power pack as it was said to be faulty but still no improvement. And ideas? Many thanks

 

[QBhoy]

Hi all, i have a Mercury 1998 150 V6 efi 2 stroke, it usually starts well and runs great on the first start when its cold, once it’s turned off and sits a bit it starts but only 3 cylinders seem to be firing and it doesn’t get any better. I changed the power pack as it was said to be faulty but still no improvement. And ideas? Many thanks

If this is when it’s on the trailer and after just a short run, any chance it could be a battery issue ? Wouldn’t be the first time a highly electrically dependant efi outboard has thrown this issue at its owner…often fooling (including me a couple of times) then into thinking otherwise…because it seems to start ok. Definitely worth checking that you are getting a charge from her and definitely try another battery. Just in case, that’s all.

 

[Josh13250]

Battery is good, just checked and fuel pressure is bouncing between 0 & 20 psi, the fuel pump was grounding and making contact, and a CDI may be an issue.

 

[Faztbullet]

One side of stator could be dropping out.

 

[Dukedog]

low fuel pressure.. should be at least 36 ta 39 lbs. and "steady" at any rpm.. idle and above... could be pump, regulator, filters, and/or ecu?..
probably not tha 3 cyl. "no fire" problem.. thats probably electrical....