40 HP Mercury stalls when given throttle #2

[bobwojo]

My son has a 40 Hp outboard that runs fine when we put a garden hose to it and run's it in the driveway (under no load) when we run it water it will idle fine and run at half of what the engine is capable of (no power) or it will die when He gives it some trottle. This problem started right after he ran out of gas. He got back home and put fuel in it and the next time he went out had this problem. Could he have damaged the fuel pump? Could there be air in the system that is keeping the pump from working properly? <br /><br />Fuel filter is Clean, was no water in bowl, New plugs installed. Could spark Adv. cause this, linkage running up under fly wheel is free not binding.

 

[rverano]

Re: 40 HP Mercury stalls when given throttle #2

I had a similar problem with a 35hp. If you pump the primer bulb while running, does the engine continue to run? Make sure the whole fuel system checks out, Vent on fuel tank open, fuel line and primer bulb ok. Has the fuel pump ever been replaced? I went through everything on mine and it ran great but could never really pinpoint what it was.

 

[bobwojo]

Re: 40 HP Mercury stalls when given throttle #2

The primer Bulb did not help, I checked the Built in tank vent and it was clear. Motor is about 1 1/2 years old, bought new, never been serviced.<br />have some new info.... Was looking at the Carb and next to the mixture adjustment screw at the top of the Carb is another threaded hole with nothing in it. Looked around and did not find anything except a rubber plug laying at the bottom of the motor case. Is this right? A air leak could easely cause this lack of power I believe.

 

[Clams Canino]

Re: 40 HP Mercury stalls when given throttle #2

Yep... check the parts list and see if the rubber plug isn't the bane.<br /><br />-W

 

[bobwojo]

Re: 40 HP Mercury stalls when given throttle #2

Went to the Mercury parts website Carburator <br /><br />could not find a rubber plug on the parts list, stiil bothere me though. On the graphic at the address above the empty hole is next to where part # 12 (IDLE NEEDLE) goes.<br /><br />Think I will send my son to the Bass Pro Shop with a picture of the carburator. and see whaqt their mechanics say. Wish there were an easier way to put the engine under load than taking it to the lake.

 

[TELMANMN]

Re: 40 HP Mercury stalls when given throttle #2

What gas did he put in? Was it new gas or old?<br />Always when having troubles put new gas in as it will always help. Also always add seafoam.

 

[bobwojo]

Re: 40 HP Mercury stalls when given throttle #2

It was new gas right from the pump. Never heard of seafoam, ill look into it.

 

[shipoffools]

Re: 40 HP Mercury stalls when given throttle #2

If he ran it out of gas it's possible he sucked some deris from the bottonm of the tank into the system a good carb cleaning might be in order. As for the fuel pump I had a similar problem with a 70 horse and a fuel pump rebuild ($11 kit about 15 mins to install) made the thing run like new again

 

[bobwojo]

Re: 40 HP Mercury stalls when given throttle #2

Yes but the filter was like new, very clean. We are going to clean out the jets though just in case something was picked up in the fuel lines after the filter.<br /><br />Anyone know what the fuel pressure should be?

 

[bobwojo]

Re: 40 HP Mercury stalls when given throttle #2

OK, took the carb apart, it was very clean, found nothing in any ports or jets but blew them out anyway. put it back together and my son says it is running better than ever. Must have been something in there that fell out in the disassembly process. <br /><br />BTW, fuel pressure is about 5-6 PSI.<br /><br />The empty screw hole next to the idel mixture screw turns out to be a vent hole for the float bowl.<br /><br />thanks for the advice...