1998 25 HP Merc

[mjh005]

Re: Electric start, tiller 25 hp Merc outboard
While under power (1/2 to full throttle) engine "suddenly" bogs out and dies. Repump gas ball(tight) and can repeat time after time never going more than 50-100 yards...ballpump looses pressure and must be pumped prior to restart. The gasline hose appears to be fine but it acts like an air or gas issue.(carbuerator??)....am I wrong? Last time out I could not get it to start at all at the dock.

 

[reka12]

Re: 1998 25 HP Merc

Something easy, is the vent open on the tank? If so, try a new hose as the check balls in the bulbs get stuck or the seat is bad. Then, look at replacing the fuel pump diaphram. That is if everything was working right before.

 

[mjh005]

Re: 1998 25 HP Merc

Yes, vent is open on tank. Wouldn't engine at least start even with bad hose? What does it take to replace fuel pump diaphram? ( what exactly is this?...thankyou!!!

 

[Longstory]

Re: 1998 25 HP Merc

If the bulb is not staying firm/going flat, you have a restriction in the fuel supply from the bulb back to the tank somewhere. The fuel pump is doing it's job if it is sucking the bulb flat. There is not any fuel coming out of the tank to replace what it has sucked out creating a vacum in the fuel line. The most common problems are as follows:

Tank not venting. Loosen tank cap & run to see if problem is corrected.

Bad check valve in bulb on tank side. If bulb pumps up to firm this may not be the problem.

Screen on bottom of pickup tube in tank stopped up/ restricted. You may have a bubble of water floating around on the bottom of tank. When water hits the screen it can totally block off fuel supply because the water will not flow through the screen.

 

[mjh005]

Re: 1998 25 HP Merc

The problem above was water in the tank as you thought may be the problem...Thanks to all for your help.