gas leaking out the top of my 75hp merc

[ahawk100]

I have a 1986 75 merc and the last time I had it out, I was leaking gas. It was leaking under neath the crowl, same side as the gas input nipple.<br /><br /> I have pulled the crowl off and I see nothing obvious, no broken hoses, no cracked gas filter.

 

[Hooty]

Re: gas leaking out the top of my 75hp merc

Take the cowling off, pump the bulb and look for the leak(s). Could be a leaking needle & seat, loose hose, etc. When you pump the bulb, you pressurize the fuel system and that should enable you to find the source.<br /><br />c/6<br />Hooty

 

[JB]

Re: gas leaking out the top of my 75hp merc

This would fit better in Merc Troubles. Going there.

 

[ahawk100]

Re: gas leaking out the top of my 75hp merc

to hooty,<br /><br />I was thinking, that when I was out the last time, I of course pumped my gas tank bulb apply pressure to the gas line. I didn't see any leaking then. I didn't see the until I started the engine. So I don't think it is leaking while under pressure only when it is running. And after I run the boat about a 100 yards, I no longer have pressure. So I have to pump the bulb again.<br /><br />Thank goodness the crappie were only 200 yards from the boat ramp, LOL. And it is 0 degrees outside, so I can't look at it yet but I am taking suggestions so I am ready when warmer weather gets here.<br /><br />ahawk

 

[Elmer Fudge]

Re: gas leaking out the top of my 75hp merc

Hey Hawk, if the bulb loses pressure,that means air is leaking into the lines,hence gas leaks out.<br />Try tightening up all the straps along the fuel lines and check the fuel pump it could well be a faulty diaphram.<br />Was the motor stalling out on you?

 

[ahawk100]

Re: gas leaking out the top of my 75hp merc

I wasn't loosing pressure until I started the engine. I could pump the bulb and I would keep the pressure in the lines. And I wasn't leaking gas, that only occurs after I start the engine. The engine starts fine and runs til the pressure bleeds off(only with the engine running). Then it dies because there is no pressure. I can then pump it up again, I will not be leaking gas. Then I start the engine and I start the whole process all over again.<br /><br />Where do I find the fuel pump? That sounds more like my problem. The fuel pump would only be goin g while the engine is running, right?

 

[rickdb1boat]

Re: gas leaking out the top of my 75hp merc

Check the gaskets where the carbs mount to the engine. Make sure the carb bolts are tight. Fuel pump is probably working, or bulb would not go flat. Check fuel tank vent for restriction. Check anti-syphon valve in fuel tank. Better yet, get a portable 6 gallon tank, new fuel line, bulb and try that. Make sure the vent on the top of the portable tank is OPEN. Then see if the bulb goes flat. I know this is probably not related to your leak problem, but one thing at a time. Follow your fuel line from your fuel tank to the pump if you plan on replacing it....

 

[ahawk100]

Re: gas leaking out the top of my 75hp merc

RB,<br /><br />I hope I am not misleading about the pressure going down. I believe the pressure is going down due the fact I am leaking that much gas after I get the engine started.

 

[Elmer Fudge]

Re: gas leaking out the top of my 75hp merc

you're going to have to go through the process of elimination and tackle one thing at a time like Rick says.<br />The vents are a good place to start,it's something thats so easily overlooked.<br />Before you attempt to do any repairs you need a service manual,it is the most valuable aid in identifing and locating parts on your motor,eg..fuel pump ect..ect.<br />they can be found by scrolling to the bottom of the page

 

[rickdb1boat]

Re: gas leaking out the top of my 75hp merc

ahawk100 <br /><br /> IF your pump is operating as it should, and it sounds like it is, it will pull the bulb into a vacuum, causing it to collapse if your vent is clogged. I understand what you're saying about the leak causing the bulb to go flat, but there is a reason for that to happen. My first thought would be to run the engine on the Muffs and try to find the leak when the engine is running. Should'nt be that hard to see the leak when the engine is standing still and you can see what's going on. Check the lines from the pump to the carbs. Sometimes a hairline crack or loose hose fitting will not show up until it's running, because the pump is then pushing fuel to the carbs and fuel lines. In particular, the ones from the pump to the carbs. The reason I think it's the lines from the pump to the carbs, is that the bulb will hold pressure until you start it. Then it drops. That tells me that the problem is not between the bulb and fuel pump. Check around the carbs and also the float bowls,in addition to the fuel lines. Then go from there.

 

[ahawk100]

Re: gas leaking out the top of my 75hp merc

well boys, now I am really confused. it is the first nice weekend and I have attached the water suction clamp to the water intake on the Merc. I fired the motor up and no leaks!!!! ran it for 15 to 20 minutes in neutral and in gear. <br /><br />anybody got any thoughts?

 

[KCLOST]

Re: gas leaking out the top of my 75hp merc

Try to squeeze the bulb while the engine is running on the muffs. Maybe that will reveal the leak that has suddenly dissapeared. It's doesn't sound like a carb problem, probably a line leak.

 

[ahawk100]

Re: gas leaking out the top of my 75hp merc

I did squeeze the bulb while the engine was running, there were no leaks.

 

[KCLOST]

Re: gas leaking out the top of my 75hp merc

Hmmmmm,<br /><br />Are you sure you are seeing a leak? You wouldn't by chance had the engine tilted up to cause gas to leak out of the carbs/airbox? That easily happens when the engine is off and excess fuel runs out by gravity?<br />Just checking....

 

[ahawk100]

Re: gas leaking out the top of my 75hp merc

nope, the enginee was running in the down position. I have seen what you are talking about and this is not the case

 

[mariner man 66]

Re: gas leaking out the top of my 75hp merc

Try checking the function of the fuel enrichment solonoid?

 

[froggy prince]

Re: gas leaking out the top of my 75hp merc

its me agian need help been looking for plack with module number can only find sr number on mottor the comp name is kiekhaefer corp can any one tell me a rough age of my mottor based on manifacture ?