350 Mag - Cranks but no start - exhaust elbows recently changed

[dolemite_1]

Hi Guys,

I have 2006 twin 350 Mag Horizon closed cooled (OW360139). Before dropping boat in water I changed the exhaust elbows. Boat ran fine on fresh water flush on land. I then dropped it in the water and ran fine again. The next day I start it up in my slip and ran fine for 2 minutes before i shut it off to hook up fresh water flush again. I hooked it up (fairly high flow of water if that matter), then tried to start and it would crank but not start.

I took out 2 of the spark plugs to look for water and found nothing. The plugs were fairly black for being a year old. My gut tells me I have a fuel issue, considering I was knocking around the cool fuel module when i replaced the seat water pump at time as exhaust elbows. I changed the dist cap about a year ago as well. I have NOT changed the fuel water separator yet this year but will be doing it today.

Whats best way to check for fuel pump issues? and will testing for spark at 1 spark plug wire be sufficient or should I check at all?

Thx

​Brian

 

[alldodge]

To check fuel pressure you would check from the shrader valve on the fuel rail.

Checking spark on one plug should be enough to find out if your getting it.

Have you checked the man overboard switch? Does the Tachometer move up when cranking?

 

[achris]

As it's an MPI engine, you may have to hook up a computer to read the codes. That's were I'd start. And checking fuel pressure.

 

[dolemite_1]

So i went down an hour ago and replaced the fuel water separator as it hadnt been done in a year. There was definite darkness in the lower white filter. The engine started right up.

I don't know if that means the issue is gone but I think it rules some things out and hopefully fixed the issue at best.

 

[alldodge]

Hope your good, but think its going to show back up