2003 40 Hp. Mercury

[Tin lid]

I have a 2003 40 Hp. mercury 2 stroke and when I troll for more than {5 min} the gasline primer bulb goes soft and the motor quits,I pump it a few times and it's ready to go again. I don't want to take it back to the dealer because his shop is far from my home. Maybe someone on this board knows of this problem and how I can fix it. Yes the vent is open.<br /><br /> Thanks Tin Lid

 

[bob58]

Re: 2003 40 Hp. Mercury

1.) Make sure tank is vented (vent plug is open)<br />2.) Check hose from tank to bulb for blockage.<br />3.) Check pickup screen in gas tank for blockage.

 

[Tin lid]

Re: 2003 40 Hp. Mercury

Thanks..... Still_learning like I said in my post the vent is open, and functions properly. As for checking the pickup in the fuel tank,that could be the problem and I will look into that. This lack of fuel problem only happens when the motor is turning below 1000 rpm's. Above 1000 rpm's I can go all day without having to pump the primer bulb.

 

[Mark.24]

Re: 2003 40 Hp. Mercury

Tin lid.<br /><br />I hope this helps! I remember reading somewhere (UK website) that 2-strokes don't like to be operated at low rpms or at idle for a period of time, there optimum is higher up the rev range. If you look at fishin boats say 20ft they have a small O/B of around 5hp for example, thats cos at trolling speeds the smaller operates at higher rpm. 4-strokes no problem, its just one of the downfalls of 2-strokes<br />Mark

 

[Tin lid]

Re: 2003 40 Hp. Mercury

Thanks M

 

[Tin lid]

Re: 2003 40 Hp. Mercury

Thanks Mark.24.... I think you're right on with the low idle and Mercury two strokes, I guess I'll just reach back every once and a while and give the primer bulb a sqeeze. I think what I was fishing for with my post was if anybody else has had this happen to them, this is my first Mercury everthing else has been OMC or Yamaha till now.<br /> The Yamaha was a 40 Hp.1997 and was a great motor,it would troll all day with no stopping because of lack of fuel. Don't get me wrong I realy like the Merc too lots of speed, great performance and better gas milage than any 40 Hp we have ever owned.

 

[steam_mill]

Re: 2003 40 Hp. Mercury

I've got a 90 hp Merc Classic 2003. I can troll with it with not problems. It doesn't stall. After trolling for 20 or 30 minutes, I usually will take it up to WOT for a minute or two to burn off any carbon etc.<br /><br />I also had a 1972 50 hp Evinrude. I could also troll with no problems. Again, I would WOT it.<br /><br />I'm wondering what spark plugs you are running. I have a 7.5 1954 Evinrude that I got this year. It would run well at WOT but crappy at trolling speed and would stall. I thought it was a carb problem and thought to rebuild it over the winter.<br /><br />Well I pulled the plugs and the gap was too low (about 20 thou). I put it to specs (30 thou) and it trolled better. I'll put them at 40 thou for next season to see if I have better results.<br /><br />Your model may have surface gap plugs so this may not fix it. <br /><br />If the spark plug thing doesn't work, I think you may have a fuel problem.<br /><br />I would check the following:<br /><br />1. Vent: Try running the engine on a portable 6 gallon. If this is what you are currently doing, try a different tank. <br /><br />2. Fuel pickup.... try a different tank.<br />3. Is your low speed mixture adjustable or fixed. I suspect it is adjustable. You may be running rich or lean. I would look at this last.<br />4. Fuel pump pressure. I have no idea how to check this. <br /><br />Hope this helps....<br /><br />Joe

 

[Tin lid]

Re: 2003 40 Hp. Mercury

Thanks for your responce steam_mill I think I will try your different fuel tank idea. My cottage buddy has a Merc and I'll try his tank. The funny thing is this motor works great at WOT and all other ranges,it just won't troll any longer than than about ten minutes when the rpm's are below 1000. I will talk to the dealer about this problem but I just hate the idea of having to trailer it to Toronto to find out that the cadidle was adjusted a little to far to the right. LOL. Well I just got off the phone with the dealer and his Prognosis is a bad check valve in the primer bulb. He is going to send me a new one. I hope this is the problem.