Issue with new fuel tank.

[cwcollins06]

Just had my old 1976 Johnson 85 HP V4 restored by a mechanic. It was my grandfather's and I don't know much about boats/outboards so I took it to a pro but from here out I want to do things myself. He built a new fuel line using ethanol resistant lines and a new bulb and installed one of the screw on fuel/water separators in line between the tank and the primer bulb. The boat still had two original 6 gallon steel OMC fuel tanks. The fiberglass shop forgot to send one of them back (they're sending it now) but in order to go out with more than 6 gallons of fuel I bought one of the Attwood 6 gallon plastic portables and the Johnson/Evinrude fitting for the tank.

So my issue is this, with the old tank everything runs perfectly just like I remember it from when I was a kid. With the new tank it'll idle for awhile and then when I increase the throttle and start getting up to speed it sucks the primer bulb flat and dies. I can pull the fuel line off the new tank and press the pin in the middle of the stem (on the old tank there are two pins next to the stem) in and hear the "hissss" of air rushing in so I assume there's a reason the new tank isn't venting. Once I vent the tank and plug the line back in the bulb expands and I can prime it again and then run for a minute or two before the bulb sucks flat again. I've tried running with the vent in the tank cap open and with it closed, same result every time on the new tank. It looks like they used the old female fittings on the new line. Is there some kind of incompatibility between the old female fittings and the new male ones? Could the spring in the old fitting be worn out and not be stiff enough to depress the pin in the new male fitting?

Also, as a side question can I get some kind of rebuild kit for the old tanks, I'd rather use them because they fit in the tank storage area in the stern and the new plastic ones don't.

 

[Tim Frank]

Re: Issue with new fuel tank.

Those tanks can be stood on end instead of lying flat, and with the fuel level above the cap they sometimes don't vent properly.
Any chance you have the tank on end?

 

[cwcollins06]

Re: Issue with new fuel tank.

No, it's not on end. I saw the warning on the side of the tank that said not to and while I usually make a habit of ignoring warnings, when explosive liquids/vapors are concerned I make a habit of doing what I'm told. I definitely thought it would be nice if I could stand it on end though, it'd save me some floor space.

I guess I'm on the right track with it being a venting issue of some kind then?

 

[RandyJ]

Re: Issue with new fuel tank.

Have you eliminated the possibility of the tank vent not being open?

I had a very similar problem on my old pontoon. In that case it was the pick up tube being stopped up inside the tank.

 

[Tim Frank]

Re: Issue with new fuel tank.

No, it's not on end. I saw the warning on the side of the tank that said not to and while I usually make a habit of ignoring warnings, when explosive liquids/vapors are concerned I make a habit of doing what I'm told. I definitely thought it would be nice if I could stand it on end though, it'd save me some floor space.

I guess I'm on the right track with it being a venting issue of some kind then?

I'd say definitely.
What happens if you have the cap really loose so it is not really dependent on the manual vent??
It may be a defective cap.

 

[cwcollins06]

Re: Issue with new fuel tank.

One of the times I tried it I loosened it up until I heard air coming in and then tried running it that way, same problem. Plus, I thought the Johnson/Evinrude fuel lines were supposed to vent through the fitting? If messing with the cap fixes it, then great, but ultimately I'd like it to function properly through the fitting to reduce the risk of spillage through a loose cap.

 

[cwcollins06]

Re: Issue with new fuel tank.

Have you eliminated the possibility of the tank vent not being open?

I had a very similar problem on my old pontoon. In that case it was the pick up tube being stopped up inside the tank.

That'd sure be irritating given that this is a brand new tank... How can I verify the pick up tube is in good shape without dismantling the tank?

 

[RandyJ]

Re: Issue with new fuel tank.

Kinda have to use your imagination on some of this crap. You can remove the hose and if you have to remove any fitting screwed into tank fitting... then blow back into it. Or even seal the tank filler neck and blow air into the tank to see what comes out. I've done it before the hard way.... just press my mouth on the tank and blow in. When you have little to nothing to work with you just make do some times. However, you may be on track about the spring thingy which acts like a check valve in the line connector.

 

[Tim Frank]

Re: Issue with new fuel tank.

One of the times I tried it I loosened it up until I heard air coming in and then tried running it that way, same problem. Plus, I thought the Johnson/Evinrude fuel lines were supposed to vent through the fitting? If messing with the cap fixes it, then great, but ultimately I'd like it to function properly through the fitting to reduce the risk of spillage through a loose cap.

Not suggesting you run with a loosened cap regularly.....just to determine if the cap is the source of the problem or not.
As far as I know, the vent in the cap should provide all the venting required.

Just a thought, do you have a fuel line on both tanks?
If so, have you tried swapping them? And make sure that the bulb is facing the right way....should be an arrow indicating fuel flow direction.

 

[cwcollins06]

Re: Issue with new fuel tank.

I only have the one fuel line. I figured the same thing about the vent in the cap, but I tried venting the cap using the vent built in and it still didn't work. I may change out the female fitting on the tank end and see if that makes the difference. I can't think of any other part (other than the clogged pick up line) that would cause the old tank to work and the new tank to not work. Unfortunately I don't think I'll be taking her out for a couple of weeks so I won't get to test my theory for awhile.

 

[RandyJ]

Re: Issue with new fuel tank.

Jus' so you know... you're not the only one with this problem. I've got an i/o bass boat with a built in tank that the check valve is clogged. I can't get to it without major cutting & fiberglass work. Recently I was restoring a 1972 50 horse johnson. I purchased a brand new fuel connector from wally world. The o'ring would not seal onto the engine side... squirted fuel all over when I pumped the primer bulb. Just because it's new or plastic doesn't mean it will work with an old one that some other company made.

 

[cwcollins06]

Re: Issue with new fuel tank.

Down here in San Antonio we call Wally World "Wally Martinez." I try to buy all my marine parts from online stores or specialty retailers, at worst a sporting goods store that carries brands I'm familiar with. Just frightens me to buy stuff from a ginormous corporation whose mantra is "Cheaper, cheaper, cheaper..."