Mercury 25hp primer

I just bought a low hours 2001 25hp mercury 2 stroke, actually it is on a boat I bought. Looks like everything is still original so I replaced the water pump last night as the stream out the telltale wasn’t very strong. I was looking at the primer system and the plunger seems to be frozen. I had it running and was wondering if it was supposed to be hard when there is pressure on the system or if in fact my primer needs to be rebuilt. Has anyone else looked at theirs? And OMG those carb plate bolts are hard to get at….and having to remove the starter to change the water pump….

those primers are notorious for seizing up,often times the diaphragm is so hard from fuel rot and age you can almost stand on it and it wont budge, the rest of the time its the push rod is stuck in its bore.
make sure to clean out the little check ball and its seat.

I went out at lunch and got it to move, now it send gas out the weep hole on the side. I just ordered a rebuild kit for it, looks like I may be able to replace it without pulling the carb. I’ll grab a pic of the water pump, never seen one like this, the vanes were going both directions. Thanks

Had that motor purchased new. You won’t typically see a strong flow out of the telltale until the motor is well warmed up. (To the point were the thermostats open. ) Many cold water trips where you really didn’t see much flow at all at idle.

Great motor by the way.

-J.

Jon Jordan wrote:

Had that motor purchased new. You won’t typically see a strong flow out of the telltale until the motor is well warmed up. (To the point were the thermostats open. ) Many cold water trips where you really didn’t see much flow at all at idle.

Agree. I have a 97 that is exactly like this, there is not a strong tell-tale at low speeds, it kind of dribbles out even when the engine is warm. Most Mercs from this HP class and age are like this.

Not sure what is meant about the water pump. Pictures?

Grouse

Fyi – I have a new prop for that motor in the classified. Let’s make a deal.

-J.

Had that motor-ran great.—-FYI

Here is the impellar, normally when I take them out the vanes go the same direction, this one looks like a deformed starfish.

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Jon Jordan wrote:

Fyi – I have a new prop for that motor in the classified. Let’s make a deal.

-J.

I saw that, I don’t normally carry a spare prop but it may not be a bad idea.

That impeller looks like the person who changed it last seated it the wrong direction. You have to spin the drive shaft the same direction as the engine spins to seat it or it will do something like that trying to spin backwards once you start it up.

onestout wrote:

<div class=”d4p-bbt-quote-title”>Jon Jordan wrote:</div>
Fyi – I have a new prop for that motor in the classified. Let’s make a deal.

-J.

I saw that, I don’t normally carry a spare prop but it may not be a bad idea.

I am suprised by this. I have always carried a spare prop. Can prevent a very bad day.

onestout wrote:

I went out at lunch and got it to move, now it send gas out the weep hole on the side. I just ordered a rebuild kit for it, looks like I may be able to replace it without pulling the carb. I’ll grab a pic of the water pump, never seen one like this, the vanes were going both directions. Thanks

Likely broke the diaphragm and it likely won’t run at all until replaced, mine broke a few years ago and it is a 2003

Pretty sure that is the original impellar, you have to pull the starter to drop the lower and none of the paint had been disturbed until I put a wrench to it. And it is cracking like a 20 year old impellar.

I agree it looks like it was not installed with them all going the same direction….maybe answers the question of if the turn themselves the right way or not on their own once run.