[tmk126]

My '91 1900z has developed an interesting problem. When it is hot out and the boat is in the water, fuel leaks out of the filler cap. I have the cap that is mounted on the transom about a foot above the swim step. I'm assuming that since the boat sits in the water with the stern rather low, pressure from the tank is forcing the gas back out of the cap instead of the breather tube. The breather tube is mounted on the transom and has quite a bend in it, I'm afraid to reroute the breather tube but don't know what else to do.
Hoping one of you guys has a better idea.

[mikeyt]

It sounds like the breather tube may be blocked which would cause a pressure build up in the tank & force gas back up thru the filler tube.

[tmk126]

I removed the breather hose and blew it out, didn't help. If I remember correctly the outlet for the breather hose on the fuel tank is behind the inlet for the filler hose so when the tank is fairly full, they are both "submerged" and the air in the tank is at the front. Make sense?
The solution last summer was to keep the tank less than 3/4 full, but that doesn't really work for me.

[mikeyt]

The breather tube is one of two options for venting the tank when fuel expands due to ambient temperature. The other is back thru the filler tube. I would ensure that the point of entry to the tank is clear & that the the thru hull fitting is also clear. Try disconnecting the line at the tank & leaving it attached at the thru hull fitting then blowing it out. Also check the fuel cap to see if it is providing a good seal. The gaskets in the fuel caps wear out over time which allows water to enter the fuel tank and/or fuel to expand back out if the breather line is blocked or not properly installed (ie kinks or sharp bends in the line). Ideally i would guess than the breather line connection at the gas tank should be near the front of the tank or at minimum somewhere ahead of the fuel connection to accomodate the normal running attitude of the boat or when its sitting on a trailer. I'm not really sure where mine is mounted. The only other option i can think of is simply not filling the tank completely to allow room for fuel expansion.

[tmk126]

Thanks for the reply, I guess I'll have to wait until it gets over 50 degrees to mess with it. It sure has been a long winter here in the NW! Thanks to the great info on this site I just received a set of smart tabs I'm going to install this week.
I had no idea there were so many proud Mariah owners out there.

[limarian]

i need to replace my filler cap - looking at it from underneath i cant see a breather - it just seems connected into a rubber tube with a a bulldog clip - i am hoping i will be able to undo that if i can find a small child to get in there and just withdraw the filler cap assembly and replace - i would welcome any ideas on where to find a nice chrome replacement and the size of the filler tube - my local chandler says probably 1.5''.

[ColoradoDiablo]

Try here in the "Original Mariah Parts & Vendors List".

http://www.mariahownersclub.com/foru...dors-list.html

The Indy style Filler is still available , and there are even a few on Ebay.

[limarian]

yes i did have a look here some monhs ago - but they said the original attwood was no longer made - there are four screw holes on the one there at the moment and again that is difficult to match - thanks for the reply anyway - regards

[Andy b]

I know this is a bit of a thread revival, but do all the Mariah’s on your side of the pond vent their full tanks through the cap?
The reason I ask is my tank is vented on the port side just forward of mid ships.
If you look here it's just below where the checker starts

[limarian]

doesn't have a vent hole - must vent from somewhere i suppose but certainly no holes on the hull.