50 hp merc soft primer bulb

[58rude]

I have a 2005, 50 merc, two stroke. Primer bulb goes soft while ideling, or low rpm for more than 10 min. Usually happens when I am having to go slow through a alot of stumps in the river channel. Prime it back up and she will run fine on plane. Any ideas.

 

[Silvertip]

Re: 50 hp merc soft primer bulb

That is perfectly normal. The primer bulb gets firm when the engine is not running because it's purpose is to fill the float bowls on the carburetors. when full the needle and seat close thus preventing more fuel entry. When the engine is running fuel is "sucked" through the bulb so it will not stay firm. However, if the bulb is being sucked flat, then that does indicate an issue and is usually the result of a blockage between the bulb and the pickup in the fuel tank.

 

[58rude]

Re: 50 hp merc soft primer bulb

I don't understand why it only does it at low rpm. It will actually run the carbs dry and the engine dies.

 

[58rude]

Re: 50 hp merc soft primer bulb

Anyone

 

[Faztbullet]

Re: 50 hp merc soft primer bulb

Its called a primer bulb as thats all it does, primes/fill fuel system. From what your posting you have a low speed suction issue either from a weak fuel pump diaphram or a air leak at fuel filter or a hose connection. I will place my bet on diaphram due to year model and the crappy fuel made today.

 

[Silvertip]

Re: 50 hp merc soft primer bulb

If the engine dies it is because fuel is not reaching the engine and that has nothing to do with the primer bulb. A weak fuel pump is very likely the issue if you need to keep pumping the primer bulb to keep it running. Squeezing the bulb essentially takes the place of the non-functioning fuel pump.

 

[j_martin]

Re: 50 hp merc soft primer bulb

I'd check for a small leak in the fuel line between the primer bulb and the fuel, including the down pipe in the tank.

The lift is about the same no matter how much fuel is pulled. A small amount of air intrusion might not be noticed when a lot of fuel is flowing, but the same leak at low flow could flow in enough air to make the primer bulb unusually soft, and eventually get into the fuel pump and stop it.

Easiest way to check for air is to add a short piece of commodity clear hose between the fuel connector and the fuel line to the primer bulb.

hope it helps
john

 

[krawczmwk]

Re: 50 hp merc soft primer bulb

I may need to start a new thread, but since this is dealing with the fuel line I thought I would ask. I have the original gas tanks that came with my 85 basstracker. It has an 50 hp merc. I think they are merc gas (2) 6 gal tanks since they look similar to the ones in the mercury operation manual I have. They are metal tanks and the insides are in good shape. However, one of the caps need to be replaced,, I think. Does anyone know where I might find new caps. One of the caps has been replaced in the past and I am not sure the screw vent is actually venting.
thanks
mark

 

[58rude]

Re: 50 hp merc soft primer bulb

I'll rebuild the pump and check all my connections good. Thanks alot.

 

[j_martin]

Re: 50 hp merc soft primer bulb

I may need to start a new thread, but since this is dealing with the fuel line I thought I would ask. I have the original gas tanks that came with my 85 basstracker. It has an 50 hp merc. I think they are merc gas (2) 6 gal tanks since they look similar to the ones in the mercury operation manual I have. They are metal tanks and the insides are in good shape. However, one of the caps need to be replaced,, I think. Does anyone know where I might find new caps. One of the caps has been replaced in the past and I am not sure the screw vent is actually venting.
thanks
mark

Yer right. It's called hijacking a thread. Start a new one.