2001 Merc 125hp Fuel Bulb aways bleeds down

[ChrisMac]

Ever since I purchased my boat brand new it seems that if it sits for more than 10 minutes I have to reprime the fuel system by pumping the priming bulb. Sometimes I can pump it all day long and it won't get hard then sometimes I pump it 3 times and its hard. I recently discovered that the dealer didnt put a 1 way check valve at the beginning of the fuel tank. I replaced the valve and it seemed to help but not fix the problem. I'm almost tempted to install a inline low pressure fuel pump!<br /><br />Mac

 

[Bob Kimber]

Re: 2001 Merc 125hp Fuel Bulb aways bleeds down

Hi ChrisMac,<br /><br />It almost sounds if you have an air leak somewhere in your fuel line. Another thing to check is the position of your fuel bulb, is it lying flat or in a vertical position? when you go to prime it you should always hold it with the arrow pointing up (fuel flow going up) as much as possible, this allows the non return valve on the inlet side of the bulb to close under the weight of fuel and backpressure when you squeeze the bulb, this allows you to prime much more effectively.<br /><br />If bulb hangs with the arrow pointing down, when motor is shut down the non return valve (check valve) on the inlet side will open and let the pressure feed back to the tank, this could be why you have noticed a slight improvement since fitting a check valve at the tank.<br /><br />In the seventies when doing a fuel pump pressure test on OMC motors it was part of the specifications to ensure the bulb was hanging verticaly with arrow up (fuel flow up) approx 12" below fuel pump on motor.<br /><br />Bob

 

[marinegrh]

Re: 2001 Merc 125hp Fuel Bulb aways bleeds down

what kind of primer bulb do you have, if its a cheapo, you will have many problems, try replacing it with an omc, 5/16 for you 125, they seem to produce the best bulb on the market, even though its made in mexico, and look for air leak throught the entire fuel system even the carbs, <br />are you leaking any fuel in the motor pan?

 

[ChrisMac]

Re: 2001 Merc 125hp Fuel Bulb aways bleeds down

I originally started out with the factory Mercury priming bulb then replaced it with one I found at wallmart made by Sea something. When priming my bulb it's always horizontal. I've checked for fuel leaks there never was any gas in the engine pan. I just had the carbs off the motor as I was having major problems. I found some slight dirt residue like a dirt ring around the needle but it really wasnt dirt it just like a stain. I cleaned all the needles and it seems like the problem went away. But then the other night it was hard starting and the primer bulb would not get hard no matter how many times I pumped it and the rough running happend again for about 5 minutes. I plan on ordering carb kits and replacing all the needles. One thing I'm slapping myself for is not cleaning the seats with a swab or something to that effect. One another note I can not believe how simple these carbs are! <br /><br />Mac

 

[Bob Kimber]

Re: 2001 Merc 125hp Fuel Bulb aways bleeds down

ChrisMac,<br /><br />I have never had any problems with the genuine merc bulbs, been using them for over 25 years and always get a good run out of them. Just for interest try holding the bulb up when priming as I suggested, you may be surprised, I have seen people have a lot of problems if you have any air in the bulb or the line between bulb and tank. The check valve in the bulb will not work correctly if it is horizontal with air in bulb, in extreme cases the line has to be disconnected from motor, held up above bulb with a finger over end (assuming you have a direct conection and not a coupling), squeeze bulb and release air from line at the same time, then seal end of line with finger and allow bulb to suck in fuel, keep repeating until you have a good flow of fuel from line when squeezing bulb.<br /><br />Bob

 

[jim dozier]

Re: 2001 Merc 125hp Fuel Bulb aways bleeds down

Never clean float needles or float valve seats. If you have gone to the trouble of getting the carbs apart, replace them, they're not that expensive. I'm betting you have done what many other have, an incomplete carb fix/clean. Pull the carbs off when you get a complete rebuild kit and dismantle them, remove all the jets and float valve, soak them in carb cleaner, blow them out with compressed air, and replace the parts that come in the kit. I predict complete success. While you fooling around rebuild the fuel pump just for good measure.

 

[ChrisMac]

Re: 2001 Merc 125hp Fuel Bulb aways bleeds down

Jimd do you know a good online source for ordering the carb kits?? When I was troubleshooting the engine I didn't really know if it was a carb issue or not. When I first bought the boat brand new 2 years ago I had almost the same problem the first week out and the dealer said they just cleaned the needles so that what I was shooting for. I still can't believe I had carb problems on a 2 year old engine!! Could this problem be from not having a water separator?<br /><br />Thanks for the responses guys!<br /><br />Mac

 

[jim dozier]

Re: 2001 Merc 125hp Fuel Bulb aways bleeds down

Most outboard carbs don't like dirt, water (in the fuel), or to sit unattended for more than a month (they get lonesome and to spite you they form a gummy deposit in the jets and orifices). So even if it is only 2 years old but sat all winter with no one to talk to I am not surprised at her petulant behavior. I don't know an online source for Mercs, I have a Suzuki and I use brownspoint.com (Suzuki dealer). Merc parts should be easy to come by someone here will know.

 

[ChrisMac]

Re: 2001 Merc 125hp Fuel Bulb aways bleeds down

Actually my carb's looked brand new inside.The only trace of dirt was a discoloration on the rubber point on the needle which whipped off with my finger.<br /><br />Mac

 

[DJ]

Re: 2001 Merc 125hp Fuel Bulb aways bleeds down

Chrismac,<br /><br />The long Mercury fuel line connectors are notorious for air leaks. There should be an O ring on the fuel (hose end) fitting and another inside the female fitting on the engine.<br /><br />Those often get neglected.

 

[ChrisMac]

Re: 2001 Merc 125hp Fuel Bulb aways bleeds down

dJohn are you talking about the quick connect fitting?? I have just straight fuel line from my tank to my motor. There no place for a o-ring<br /><br />Chris