In Tank Vent tube Kinked and length

[Boland01]

I've got a 1991 3.0L Mercruiser. Trying to get it up and running. Last night on the first try it ran OK for about 5 minutes and then died. Took a while to start it but when we did we had to drive it back to the launch at just above idle in gear. I rebuilt the carb and replaced the fuel filters. They are clean. When you accelerate the boat the jets shoot fuel into the carb for at least a couple seconds.

After reading a bunch of posts I am suspecting something in the fuel tank. Whenever I try and put gas in the tank I can get 2-3 gallons in and then it tries to come back out of the filler neck. leaving it sit a while in the sun and trying to open the gas cap relases alot of pressure plus gas tries to come out. I also verified I only have a half a tank of gas. The vent hose is clear although it did have some fuel in it when I blew it out.

Taking everything out of the tank I noticed the vent line in the tank is nylon and measures about 40" long. I'm not sure how or why it has such a long pick up tube. it is alot longer than my fuel tank. It also has a kink so I suspect that may be the culprit. Can I cut the pick up tube back a bit, maybe in half?

Do you think this is the culprit for the boat not running right after it's been in the water for a while and the reason I can hardly put gas in it? Thanks for your help.

 

[Don S]

Re: In Tank Vent tube Kinked and length

I have no idea what that is in your picture, I have worked on boats for a living for 30 years and never seen anything like that.
A vent is nothing more than a hose barb on top of the tank (Typically for 5/8" ID hose), nothing goes into the tank.

 

[Another retired guy]

Re: In Tank Vent tube Kinked and length

All of the problems you list appear to me to have one thing in common - the vent is blocked. There should be nothing attached to the vent opening on the inside of the tank, and the line from the tank to the external vent fitting has to be clear. Also, the vent hose should not have had any fuel in it. The hose has to run upwards from the tank to the vent fitting with no low spots. It can loop UP but not DOWN. Any liquid in the vent hose has to either be able to drain back into the tank, or outside of the boat.

 

[Boland01]

Re: In Tank Vent tube Kinked and length

OK, cut 6" or so inches off of the vent hose. Now there is no longer a dip going down in. Hopefully, this solves my issue. Thanks.

 

[Another retired guy]

Re: In Tank Vent tube Kinked and length

OK, cut 6" or so inches off of the vent hose. Now there is no longer a dip going down in. Hopefully, this solves my issue. Thanks.

Still not sure we're on the same wavelength This nylon tube inside the tank has nothing to do with the vent. The vent just allows air into and out of the tank. When you say you cut 6" or so off the line, are you referring to the mysterious line inside the tank, or the vent line running from the tank to the external vent fitting?

 

[Boland01]

Re: In Tank Vent tube Kinked and length

Sorry for the confusion. I completely removed the mysterious nylon tube from inside of the fuel tank. I also then shortened the rubber vent hose that runs from the outside of the fuel tank to the outside of the boat. The rubber hose now has no dips in it and the nylon tube is gone. It appears I have (hopefully had now) two seperate vent issues going on.

Tomorrow I'll fire up the boat and see what it does.

 

[Another retired guy]

Re: In Tank Vent tube Kinked and length

Ok, hope it works Would appreciate you posting the result - it may help someone else with a similar problem.

 

[Boland01]

Re: In Tank Vent tube Kinked and length

Will do. Just added a few more gallons of gas to the tank now. Before it would back up in the fill tube and not want to go into the tank. Went right in this time. That's a big step in the right direction.