gas problem

[wordmaster]

I have a pontoon with a 1982 Evinrude 90 hp motor. It has a 6 gallon metal tank under the back seat and a 12 gallon metal square shaped tank sitting on the back.

The 6 gallon is easy to remove, just pick it up, but the 12 gallon is there to stay without some major rebuilding to get it back on.

The motor will run fine, then start slowing down, missing, even die. You can change tanks and it will run fine again...for a while. I have replaced the gas hose and hose fittings, but no help.

My best guess is that both tanks have some trash in them that, with the motor pulling, causes the strainer to stop up after a while. Without the motor pulling with sloshing around, it clears back up.

What I need to know is what is the best way to clean the tanks. The 6 gallon of course has the lip inside so that simply rinsing and turning it upside down will not let the trash out. And, as mentioned, the 12 is more or less there to stay.

Any and all help greatly appreciated.

[hoytedow]

Beano. Oh, wait. Different kind of gas problem. Try siphoning off the gas, then fill it with water and siphon again, moving the siphon hose along the entire bottom of the tank, until you have cleared away as much debris as possible. Hook a shop vac to the fuel line and pull whatever remaining water out that way before refilling the tank. Try tilting the tank(whole hull if necessary) a few degrees to concentrate all the rubbish in one small area before siphoning.

[wordmaster]

Thank you Hoyt...hope this works better than the beano did....

[hoytedow]

He who masters words, masters the world.

[capt littlelegs]

Originally Posted by wordmaster

I have a pontoon with a 1982 Evinrude 90 hp motor. It has a 6 gallon metal tank under the back seat and a 12 gallon metal square shaped tank sitting on the back.

The 6 gallon is easy to remove, just pick it up, but the 12 gallon is there to stay without some major rebuilding to get it back on.

The motor will run fine, then start slowing down, missing, even die. You can change tanks and it will run fine again...for a while. I have replaced the gas hose and hose fittings, but no help.

My best guess is that both tanks have some trash in them that, with the motor pulling, causes the strainer to stop up after a while. Without the motor pulling with sloshing around, it clears back up.

What I need to know is what is the best way to clean the tanks. The 6 gallon of course has the lip inside so that simply rinsing and turning it upside down will not let the trash out. And, as mentioned, the 12 is more or less there to stay.

Any and all help greatly appreciated.

Check the tank air vents are open and the hose connections are good, could be pulling air.

[Bglad]

Cleaning the tanks is a worthy cause but be very careful using a vacuum cleaner or any other electric appliance to clean it out you could turn it into a flame thrower or bomb!

If the tanks are not above the powerhead you might try elevating the smaller tank to see if the motor performs better with fuel siphoning to it. You may have a worn out fuel pump. That might explain while it runs ok for a while after you switch tanks and pump the bulb. The full carburetors work until they begin running out of fuel.

[hoytedow]

Originally Posted by Bglad

Cleaning the tanks is a worthy cause but be very careful using a vacuum cleaner or any other electric appliance to clean it out you could turn it into a flame thrower or bomb!

If the tanks are not above the powerhead you might try elevating the smaller tank to see if the motor performs better with fuel siphoning to it. You may have a worn out fuel pump. That might explain while it runs ok for a while after you switch tanks and pump the bulb. The full carburetors work until they begin running out of fuel.

Which is exactly why you fill it with water first, to drive out any flammable liquids. Did you not read the post?

[wordmaster]

Hopefully it is not a fuel pump. The motor may run good as long as an hour or as little as 10 minutes after changing tanks. Also, the large tank is above the motor.

[powerabout]

Does the primer bulb start to go flat when the motor misses, can you squeeze it and does the motor recover?
What happens if you press the choke while its dying?

[Bglad]

Hoyt, I read fine even better with the big red letters. If gas remains in the fuel system the shop vac can be a hazard...

[wordmaster]

Most of the time, the bulb goes flat or loses its hardness. Sometimes pressing the choke speeds it up. Sometimes, working the bulb makes it better, but usually not once it gets bad.

[hoytedow]

Originally Posted by Bglad

Hoyt, I read fine even better with the big red letters. If gas remains in the fuel system the shop vac can be a hazard...

You are right. We must never assume the people reading the thread are competent enough to let some water dribble from the fuel line before hooking the shop vac to it in order to finish the desiccation process.

[CDK]

Originally Posted by wordmaster

Most of the time, the bulb goes flat or loses its hardness. Sometimes pressing the choke speeds it up. Sometimes, working the bulb makes it better, but usually not once it gets bad.

There is your answer!
Run the engine with the filler cap removed. If OK, the vent is doesn't work, if not, the fuel line is clogged. Hoytedow told you how to proceed then.

[Submarine Tom]

OR, borrow another little, portable tank and try it.

It might prove most enlightening...

-Tom

[Ike]

Does it have an antisiphon valve at the outlet for the 12 gallon tank? Check and see if it's clogged. Also the springs in those things get old and they need to be replace. If the fuel line runs uphill to the engine you don't need it at all.

Check to make sure vents are not clogged. Bugs like to build nests in vent lines.

I would echo the comments about using a shopvac or any electric motor powered device. Be damn sure there is no gasoline vapor present or you will end up with a permanent sunburn.

Tom's suggestion about borrowing another tank and trying it is excellent. It may not be the tank and fuel lines at all.