2.5 hp Mercury starting problems

richg99

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Dale is a VERY smart guy. I listen to him.

It's funny that many outboard motors have their own little idiosyncrasies. Once learned, they behave.

I had a 50 hp Johnson that wouldn't start without simply tilting it back a bit. My mechanic explained how gravity and the carburetor system needed that to work. Duhhh.
 

Texas Prowler

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....and the skill and experience to go with it!
I do routine maintenance on my John Deere riding mower and small mower - same thing for my 1995 Silverado, but that's it. Beyond that, I pay the very high cost of repairs i.e. the 2.5hp.
Well there's not much talent or experience needed to take these apart. Just a manual/ or parts diagram and keep track of parts. Lol It's just that easy.

It was my first time lol and it's been 7yrs. Motor still runs like butter.
 

Ironhorse2022

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If you do your own maintenance on mowers and vehicles, I bet you have the skills to start learning how to maintain these simple machines. Of course, not everybody wants too and that’s cool too. It’s just there’s a real sense of accomplishment and independence that comes from being able to do certain tasks on your own (not to mention huge $$ savings). For me, I have to get over the fear that I’m going to destroy something because I’ve not done it before. Not saying that hasn’t happened but it’s yet to happen to the extent I couldn’t fix it with new parts. Even when that goes wrong, the added cost of the new part is usually still less than paying someone to fix it for me. My unrequested advice would be to get a good service manual, read up on the repair ie carb ID and restrictor plate, and then talk it thru with the guys on this forum. They’ll help you thru the repair process and you’ll have a win under your belt. Next time, you’ll feel a little more confident and it just keeps getting easier. At least that’s been my experience. Certainly, there may be times when paying someone to fix it is the smart move (like in the middle of fishing season when you want it done fast or specialized tools are required). Enjoy that little motor - it’s a good one once you get used to it and any bugs worked out.
 

senkosam

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Thanks IH !
My problem mostly is reassembling the parts I just took apart. It happened with a Daiwa reel that had an anit-reverse problem. It took me forever to get it back together not to mention the tiny parts requiring tweezers to hold them.

Calibration is also what I'm worried about when it comes to motors. Maybe what you suggest doesn't require too much of it, but the idea of the frustration of it not being done right discourages the attempt.

5hp might be a bit too powerful for a 12' jon boat don't you think?
 

Stand Up

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If you do your own maintenance on mowers and vehicles, I bet you have the skills to start learning how to maintain these simple machines. Of course, not everybody wants too and that’s cool too. It’s just there’s a real sense of accomplishment and independence that comes from being able to do certain tasks on your own (not to mention huge $$ savings). For me, I have to get over the fear that I’m going to destroy something because I’ve not done it before. Not saying that hasn’t happened but it’s yet to happen to the extent I couldn’t fix it with new parts. Even when that goes wrong, the added cost of the new part is usually still less than paying someone to fix it for me. My unrequested advice would be to get a good service manual, read up on the repair ie carb ID and restrictor plate, and then talk it thru with the guys on this forum. They’ll help you thru the repair process and you’ll have a win under your belt. Next time, you’ll feel a little more confident and it just keeps getting easier. At least that’s been my experience. Certainly, there may be times when paying someone to fix it is the smart move (like in the middle of fishing season when you want it done fast or specialized tools are required). Enjoy that little motor - it’s a good one once you get used to it and any bugs worked out.

I use my camera to take pictures of things before, during and after the repair. This helps in case you forgot how it looked beforehand. That's good advice @Ironhorse2022 That is how I learned to repair motorcycles.
 

Texas Prowler

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Ah yes. keeping track of parts. Not possible with my lack of short-term memory.
Hey don't mind me. I am just trying to motivate you and let you know you can do anything you put your mind to. Literally...

Seem that diy has become thing of the past. These days everyone directs a person to someone who can make the repair vs empowering.

You may not feel the desire to take on the task, just know it's easy. Like I would not pay a shop easy. So easy a kindergarten kid could knock it out in a day.

Hp to weight ratio. Let's say the 2.5 and 3 share the same engine block. The difference is likely the carb and the reeds plates behind the carb, which you would swap for the next up and be done.

Now if the 2.5 shared the same engine block as the 4 or 5hp you would still swap the same parts and not gain any weight.

Ultimately you would make the most of what you have without any detrimental side effects.

Tuning. Simple idle a/f screw. Not much to it.

Peace be with you.
 

Ironhorse2022

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Yup, a camera is my friend during disassembly. Never think I’m going to need them but always glad I have them after the fact.

As far as worrying about it doing it correctly, I’ve realized over time that my work with proper supervision (such as this forum) is much more reliable that most “mechanics” these days. Not to say there aren’t gift mechanics but often, it’s somebody of questionable training going as fast as he can because there’s a pile of motors behind yours.
 

RaisedByWolves

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Ah yes. keeping track of parts. Not possible with my lack of short-term memory.
Here’s a tip for taking apart and reassembling almost anything.

Get yourself a decent sized piece of cardboard and mark off numbered boxes with a marker.

As you disassemble the item poke the bolts removed through the cardboard in a numbered box in the order you removed them, then place the part removed in the next box.

Having done this, reassembly is a simple matter as you just take the part from the highest numbered square and the bolts from the next lower numbered square and reassemble the item.

Learned this in tech school and disassembled and reassembled an automatic transmission before I was even able to spell transmission.
 

Texas Prowler

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Great. Looking at the specs listed in the for sale ads. Both the 2.5 & 3.5 have the same displacement. I'd bet same cam as well. That said if you ever got to the point where you wanted to upgrade id swap carbs and that may just be all. That 2.5 is a detuned 3.5
 
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airshot

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5hp might be a bit too powerfUll for a 12' jon boat?
Not at all....most are rated for 5 to 10 hp for the wider, deeper ones. My 12' is a smaller model, not as wide and deep as other models and it has a 5 hp rating. Used to own a river jon boat, extra wide and deep 12' that gad a 10 hp rating, and yes, it would fly with my 9.9 OB
 

senkosam

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I would also and mostly use the motor on a 10'v bottom when solo. Seems to me 3.5 or higher would be too powerful.
 

RaisedByWolves

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I would also and mostly use the motor on a 10'v bottom when solo. Seems to me 3.5 or higher would be too powerful.
I would be comfortable with 6-8 hp on a boat that size, but that’s just my opinion and on the waters I frequent.

Wind, tides, weight and oncoming inclement weather (lightning in a tin boat is no fun) can all play a part in the decision for me.

My 12’ mirrocraft was set up for two people plus gear and while my 9.9 was ok and fun enough, I really wanted a 15 hp on it.
 

senkosam

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In any case, today it wouldn't start after the 5th time and I had to row back into a 10mph chilly wind at least a mile to get back to the dock. Of course I left the trolling motor in the truck thinking the motor would have no problem starting.
Speed was good otherwise. Big Deal! :(
 
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