I have a 1997 Mariner 150HP EFI.  Boat has been running a little rough lately.  A few times it would just start acting like it was running out of gas.  I would switch tanks and the boat would run great for a few trips and start doing it again.  It has a factory installed oil type water/fuel seperator mounted on the side of engine.  I have owned this boat for a few years and I have used ethanol free gas always.  The previous owner only used ethanol free gas as well.

 

I pulled the filter off today and poured the fuel in a glass jar.  It did have some water in the filter so I do see it is doing its job.  This is the first time I have pulled this filter since I have owned the boat.  Could this be the problem?  How much water in that filter is normal?  I want to avoid carrying to the shop if this is an easy fix.  

 

Should I siphon all the gas out and try a new filter and new gas?

It could be the fuel.  It also could be an air leak in the fuel line.  It could also be a plugged vent line.  It could also be the filter. 

 

You say you switched tanks.  What kind of tanks?  Are they the tote around six gallon type?  Does each have its own fuel line, or, when you switch tanks do you disconnect the fuel line at the tank?

 

I have a John Deere lawnmower.  The vent in the top of the gas cap gets plugged with dust, maybe every two or three years.  I'll fill the tank, and the motor will run out of fuel when I use up about a quarter of a tank.  I have to poke a small wire into the hole in the center of the cap to clear the clog.  With the vent clogged, as fuel is burned it forms a partial vacuum in the tank.  At some point the fuel pump can no longer draw fuel from the tank.

 

While you use non-ethanol gas,  the fuel line will still deteriorate over time, just not as quickly.

 

Have you changed the filter, or did you just pour the water out and put it back together.  Have you been out since you got rid of the water?  Have you checked/cleaned/replaced the filter on the motor.  Is the filter you pulled the one on the motor, or do you have a separate filter?

 

More information is needed.

Well the first thing I would do, is change that filter, and add some star-tron and seafoam to the gas then see what happens.

I try to change that filter annually.  Its a cheap insurance that water does not make it into the motor.  I also always put Sea Foam in the tank when I put gas in it.

It could be the fuel.  It also could be an air leak in the fuel line.  It could also be a plugged vent line.  It could also be the filter. 

 

You say you switched tanks.  What kind of tanks?  Are they the tote around six gallon type?  Does each have its own fuel line, or, when you switch tanks do you disconnect the fuel line at the tank?

 

I have a John Deere lawnmower.  The vent in the top of the gas cap gets plugged with dust, maybe every two or three years.  I'll fill the tank, and the motor will run out of fuel when I use up about a quarter of a tank.  I have to poke a small wire into the hole in the center of the cap to clear the clog.  With the vent clogged, as fuel is burned it forms a partial vacuum in the tank.  At some point the fuel pump can no longer draw fuel from the tank.

 

While you use non-ethanol gas,  the fuel line will still deteriorate over time, just not as quickly.

 

Have you changed the filter, or did you just pour the water out and put it back together.  Have you been out since you got rid of the water?  Have you checked/cleaned/replaced the filter on the motor.  Is the filter you pulled the one on the motor, or do you have a separate filter?

 

More information is needed.

Boat might be equipped with 2 tanks.

I change my fuel/water seperator filter every fall.

My fuel line cracked at the brass fuel line connector on the fiberglass well area. Could not see it very well as it cracked on the bottom of the line. It would be fine.......then it would flex a little and suck air.........quite the feeling humping across the water at 40-50 and all of the sudden......motor just dies.

Easy emergency fix......cut the end of the line off and put it back on and tighten clamp.

Then replace fuel line at first opportunity.

My fuel line cracked at the brass fuel line connector on the fiberglass well area. Could not see it very well as it cracked on the bottom of the line. It would be fine.......then it would flex a little and suck air.........quite the feeling humping across the water at 40-50 and all of the sudden......motor just dies.

Easy emergency fix......cut the end of the line off and put it back on and tighten clamp.

Then replace fuel line at first opportunity.

 

Always carry a spool of electrical tape with you.  Get a quality tape such as 3M.  The cheap stuff is junk.  It will not stretch as well, nor will it adhere as well as the good stuff.  If you have an air leak, and not enough fuel line to cut it out, you can wrap it tightly with three or four turns around the hose, and it will stop the air leak.  It's also good for emergency fixes if a wire gets chaffed through the insulation and shorts.  Again. a few tight wraps will protect the conducting core of the wire until you can make proper repairs.

 

It is also handy for first aid at times.  I cut my finger open on a table saw, put a gauze pad over the cut, then two or three tight wraps staunched the bleeding.  The doc in the ER laughed when he saw it, but had to admit it did a better job than plain adhesive tape.

 

Don't leave home without it.

Always carry a spool of electrical tape with you.  Get a quality tape such as 3M.  The cheap stuff is junk.  It will not stretch as well, nor will it adhere as well as the good stuff.  If you have an air leak, and not enough fuel line to cut it out, you can wrap it tightly with three or four turns around the hose, and it will stop the air leak.  It's also good for emergency fixes if a wire gets chaffed through the insulation and shorts.  Again. a few tight wraps will protect the conducting core of the wire until you can make proper repairs.

 

It is also handy for first aid at times.  I cut my finger open on a table saw, put a gauze pad over the cut, then two or three tight wraps staunched the bleeding.  The doc in the ER laughed when he saw it, but had to admit it did a better job than plain adhesive tape.

 

Don't leave home without it.

Yep.....absolutely!

Roll in the boat tool kit.......roll in my desk at work.....multiple rolls at home.

I have 2 tanks on the boat. A 17 gallon under my seat and a 34 gallon in the back compartment.  I don't have time to really diagnose and go through all the troubleshooting. I carried to shop this afternoon.  Will keep people posted.

 

Thanks for all the replies.