Question about Evinrude pressure gas tank

[duckland23]

I was wondering How the pressure tank works . My tank when I press in the fuel part on the hose it squrts gas out of it will that mean its working right to get fuel up to the carb on my evinrude fleetwin 7.5 hp 1957 . Im rebuilding the carb and was wondering if you had a leak from the tank anywhwere on it will it affect the way the motor will run or for fuel devlivery . Im having a problem keeping the motor running , it will only stay runing on fast idle . So if im leaking air from the tank or sucking in too much air will this make the tank not work the way it should . Im asking this before I buy the gasket kit for the tank . I bought the carb rebuild kit and did that , but am waiting for the lead shot for the welch plug , I ordered one from ebay for 2.00 , my carb was missing it and the part list showed it in there . So I think thats part of the problem too . But I heard that if your not getting a good seal on the tank that can cause a problem, am I right .

 

[1946Zephyr]

Re: Question about Evinrude pressure gas tank

You want absolutely no air or fuel leaks in your system. You want to make sure the o-rings in the connector are in good shape and you want no leaks in the tank, itself. You can buy rebuild kits for your tank, at vintageoutboarb.com. You may likely need a rebuild.

 

[F_R]

Re: Question about Evinrude pressure gas tank

I was wondering How the pressure tank works . My tank when I press in the fuel part on the hose it squrts gas out of it will that mean its working right to get fuel up to the carb on my evinrude fleetwin 7.5 hp 1957 . Im rebuilding the carb and was wondering if you had a leak from the tank anywhwere on it will it affect the way the motor will run or for fuel devlivery . Im having a problem keeping the motor running , it will only stay runing on fast idle . So if im leaking air from the tank or sucking in too much air will this make the tank not work the way it should . Im asking this before I buy the gasket kit for the tank . I bought the carb rebuild kit and did that , but am waiting for the lead shot for the welch plug , I ordered one from ebay for 2.00 , my carb was missing it and the part list showed it in there . So I think thats part of the problem too . But I heard that if your not getting a good seal on the tank that can cause a problem, am I right .

How it works----when you press the button, it pumps fuel up the hose to the carburetor. That fills the carburetor so you can start the motor. Once the motor is running, it pumps air through the second hose to the tank, which pressurizes the tank. Air pressure in the tank is what forces additional fuel to the carburetor to keep it running.

Obviously, any air leaks in the system will prevent that pressure build-up in the tank, meaning no continued fuel delivery to the carburetor. It is easy to tell if it has built pressure--just loosen the gas cap. You should get that satisfying hs-s-s- as air escapes.

EDIT: I should add that the motor should run normally for awhile even if the tank is not pressurized. "Awhile" meaning till it has used the fuel in the carburetor. Often, especially with a low level of fuel in the tank, you may have to give the button a few extra strokes once it is running until sufficient pressure has built up in the tank.

 

[duckland23]

Re: Question about Evinrude pressure gas tank

The tank has 2 gallons of gas in it and its hard to press the metal nob in . Then I release the gas full cap it release's presure from the tank . when I start to pressurize the tank should it be easy to press and make a clonking sound like some guy from you-tube with his pressureized tank . My presure tank pressure full nob is hard to fill , I press it once and theres gas in the line . if i press the gas part on the conector , gas will squrit out of it . So it seams like im getting fuel , but is it leaking air from the engine from one of the screws . I seen bubbles comming out of one of the screws . Thats a leak right . Im going to tighen the screws to see if it clears up . I think thats the main problem why it wont stay running and slow idle wont work right . ,gas supply to the engine .

 

[F_R]

Re: Question about Evinrude pressure gas tank

Pressing the primer button does NOT pressurize the tank. It only pumps gas to the carburetor. Once the carburetor is full, you can't push the button any more because there is nowhere for the gas to go. As I already said, the running motor is what pressurizes the tank.

I have a favorite saying----most carburetor (fuel) problems are "not". So, have you checked the ignition system on that motor? Have the coils been replaced yet? If not, they need to be. ALL 1957 Evinrudes have bad coils, unless they have already been replaced. When they are bad, it is often misdiagnosed as a fuel problem.

 

[duckland23]

Re: Question about Evinrude pressure gas tank

there new coils and the points look good from that I seen under the flywheel . Its a pressure tank problem Im sure of it . The carb is rebuilt and I found it missing the lead shot from someone that rebuilt it before me . Im replacing the lead shot ball in it and will try when it comes from ebay this sadurday or monday . Im also going to order the tank kit , it has a leak I seen a air bubble at one of the screws . That happen when some water spilled on the screw and I was able to see the leak . It may still run after the carb rebuild , The Ingition is hot as in a blue spark .I think if it had weak spark it would not run on fast idle at all . But its running on fast idle , but seems like it running out of fuel on the carb , I also found that the float was not set right , so lets see what happens . Maybe it will run and then I can adjust the carb fast and slow speeds . Its been a long time sence I did a carburetor adjustment , But I will work it out . After its running I can go fishing like I want to do . Game fish dont open untill the first sadurday in wisconsin , so I got untill this weekend to do it . But I can wait a week to go out on the water . Next thing I need to get is a good boat . But I need to save room for it and the money to buy it .

 

[duckland23]

Re: Question about Evinrude pressure gas tank

Update I just bought a new gas tank rebuild it from ebay for 16.00 . Its the kit with the gasket and diaphragm . The kit wont incude the round metal disc like thing that you see on vinatage outboard.com . It also dont have the 8 fiber washers like that kit has . everthing else is ok like the gas cap gasket and all the other gaskets as well . I can get fiber washers at the hardware store so I dont need them I can also make my own gasket , I use to make old pump gasket that were not avaible anymore . So I know how to make my own if needed too .

 

[truckntractorhick]

Re: Question about Evinrude pressure gas tank

did that fix the fuel leak on your tank?

 

[duckland23]

Re: Question about Evinrude pressure gas tank

Not sure sure about the leak yet . Im getting the kit on wenesday afternoon and I can post if I fixed it . But It seems to be pumping fuel by pressing in the check valve and pressing the primer botton , the fuel is squrting out this way by pressing it . Im still going to replace the gasket set . and check for clean operation of everthing . Ill let you know that happens .

 

[duckland23]

Re: Question about Evinrude pressure gas tank

Well guys I installed the kit with the gasket for the tank and diaphragm . I wont know if my tank is leaking anymore I need to place it in the tank now and start her up . It was kind of easy to replace the kit . One thing is I never got any screw gaskets Im wondering I will need them as well . I can use a fiber washer from the hardware store for that No biggy . But I hope it stays running . I finaly fixed the tiller handle after trial and error , Someone that owned the motor before me took it apart and replaced it the wrong way . The metal piese that holds the spring in the handle was in there wrong , thats what made it tight to turn . But I hope she runs fine .

 

[abennett1982]

Ive been having an issue with my tank staying pressurized after I put the gasket kit on my 57 cruise a day tank. Can someone please tell me what this hole is? When Im cruising along the lake, I can hear air leaking out of the hole and then my motor dies down until i start pressing the primer to fead the carb more gas.

 

[F_R]

This thread is four years old. But as for your question that is the over-pressure relief valve outlet. If it is leaking, the valve is bad. Please start a new thread if you have any more questions.