Damn Boat Motors

[johnr]

The local boat mechanic knows me by name....effn mercury motors

 

[Duckslayer100]

The only consolation to all this is I sort of enjoy tinkering with motors. My one regret in high school was not being able to take the small-engine class (which was reserved for the gang bangers and dope heads).

I've successfully resurrected a snow blower and small Mantis tiller by taking parts off, cleaning them, and putting things back together. Hopefully the old Johnson is similar.

 

[Duckslayer100]

Well....it worked! At least, it worked a lot better in my driveway than past experiences.

I ripped out both carbs, cleaned them by soaking in carb cleaner, then spraying with carb cleaner and canned air. Reassembled with new gaskets and parts, then reinstalled. She fired up first try and I barely had to choke it. Idled like a dream.

The real test will be the water on Friday, but I have high hopes!

Thanks for all the help. Now that I've done it once, next time it'll be a lot faster if I need to clean them again.

 

[Duckslayer100]

I spoke too soon. Took a half day Friday and brought my son fishing. Totally amped to get the boat in the water and hear that Johnson purr.

Well, it started a lot easier, but still wouldn't idle. Low RPMs. Almost like the idle screw was set too low, but I never touched the thing when I did the carb rebuild.

Thought oh well, let's just go. Watch the RPMs and put it into gear and took the slowest boat ride of my life. At full throttle I got less than 3,000 RPMs and was maybe going 5mph. Total lack of power.

So I don't know what the heck I did. I actually made it worse. I'm really close to just bringing the damn thing in.

 

[NDwalleyes]

I'm like you and enjoy this stuff. First hand learning is the best. Don't give up. Sounds like it's not getting enough fuel now.

 

[guywhofishes]

Yep, could be. Bad fuel pump did that to me once. Still pisses me off 6 years later. Work and work on the wrong issue. Grrrr

 

[Duckslayer100]

Yep, could be. Bad fuel pump did that to me once. Still pisses me off 6 years later. Work and work on the wrong issue. Grrrr

Would that be amazing. Do the work on carbs and suddenly the fuel pump goes out at the same exact time.

I'm going to try getting the carbs out again and really looking at the jets. I thought I cleaned them well, but maybe I missed something. If that still doesn't work, I might think about replacing the fuel pump.

 

[Brandon]

With the engine off, check to make sure the throttle is opening the butterfly in the carb completely at full throttle. Sometimes it can be easy to hook the linkage up incorrectly after removing the carbs. Just an idea

 

[WormWiggler]

I had a problem one time because the connector for the hose to motor would let air into the system. Didn't act like yours, but it was a hair puller...

 

[Duckslayer100]

With the engine off, check to make sure the throttle is opening the butterfly in the carb completely at full throttle. Sometimes it can be easy to hook the linkage up incorrectly after removing the carbs. Just an idea

That's something I never considered. I'll definitely try that, too. To be clear, open completely would be the butterfly being pretty much perpendicular to its resting position, correct?

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One other possible problem: I did notice I wasn't able to pump the bulb up completely. Just replaced the entire fuel line, so I'm not sure how it could have gone bad in a months' time. Does this point to air escaping somewhere??

 

[Brandon]

It may not be completely perpendicular but with the throttle lever all the way open you can try to move the butterfly linkage on the carb. If it doesn't move your good if it moves quite a bit then some adjustment is needed. Also, with 2 carbs make sure they are opening and closing equally.

 

[guywhofishes]

Does the primer bulb get rock hard and stay hard? (que matthews for boner humor)

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Oops, didn't see yer post.

That primer bulb not getting hard says your pump diaphrams are not sealing. EXACTLY what mine was doing. (Mercury 35hp). It was a 5 minute job to replace. GRRRRRR

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Mine had disintegrated. Probably from Devils Liquor before I knew its evils.

 

[Duckslayer100]

Does the primer bulb get rock hard and stay hard? (que matthews for boner humor)

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Oops, didn't see yer post.

That primer bulb not getting hard says your pump diaphrams are not sealing. EXACTLY what mine was doing. (Mercury 35hp). It was a 5 minute job to replace. GRRRRRR

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Mine had disintegrated. Probably from Devils Liquor before I knew its evils.

That seriously would be the height of irony if my fuel pump went out immediately after my carbs were actually fixed. Like, Karma owes me HUGE after this. I expect many, many limits of walleyes in my future or else I'm punching that bitch right in the cunt.

 

[espringers]

isn't it possible that the pump/diaphragm was the problem the entire time? maybe i missed something re a change of symptoms.

 

[guywhofishes]

i am NOT a mechanic BTW. Just sharing my experience with fuel pump misery. Maybe yours is fine? Or it was problem all along - the test run shook things loose. I had rubber bits coming free off mine.

 

[eyexer]

I would bet the carbs were plugged regardless. You have multiple issues I'd guess. Hold your bulb straight vertical and pump it to see if it gets hard. If it doesn't you have either a fuel pump issue. Or if fuel runs out the overflow in your carbs you have a float bowl issue. Only achieving 3000 rpm's means one of several things. Low/lack of fuel to the cylinders. This can be caused by multiple things. Or your rings are stuck on your pistons. linkage not opening carbs as far as they need to be. One other question. When you start it at home on the muffs did you put it in gear and make sure the prop turns freely?

 

[hogslayer]

You could still have a number of things affecting you and it is hard to diagnose over a forum thread. Motors need compression, fuel, and spark/timing to run properly. I'm going to assume your compression is good. You cleaned and rebuilt your carbs without adjusting them but it sounds like you could still have a fuel delivery problem. You could have a fuel pump problem or a plugged fuel filter or (some of these used filter screens) causing your problem and not delivering enough fuel. How old is the fuel you are using? Gas goes bad in a couple months and if it is really old it will hardly burn at all. Do you have it mixed in the proper ratio? Does your gas tank have a plugged vent? That would cause it to not be able to suck enough fuel and keep dying out unless you were continually pumping it. That could be the cause of your fuel primer bulb not staying hard. It is hard to say how much tinkering the previous owner did on it so he might have adjusted the carbs and or linkages wrong. The coils could be weak but normally they won't run at all with a bad coil most of the time. Did you replace or clean the plugs? With your motor not running right they could already be pretty fouled even if they are new. Make sure they are clean. How are the plug cables? Are you grounding out somewhere? Those old Johnsons used something called a link and sink linkage going to the carb to advance the spark timing. The more the carb opens up the more it advances the timing to compensate for the increase in rpm's. This is really touchy and if someone messed with it at all it could be pretty messed up. I would recommend first checking your compression to make sure the motor is good. Then continue to eliminate the fuel delivery variables such as the filter, fuel tank vent and possibly pump and also make sure you have good plugs and wires and fresh gas. If the linkages or carbs need adjustment I would definitely recommend taking it in to a pro if you do not know what you are doing there. Also doesn't hurt to check the iboats forums for related threads or start a new one. A lot of good info passed along on there sometimes.

 

[NDwalleyes]

I get the feeling that this motor sat for a while with fuel in the lines/system. It's a bitch to clean up.

 

[Duckslayer100]

The previous owner had it running like a top when I picked it up. No hesitation. Went into and out of gear seamlessly. Idled like a dream. Said he slow idled with it for hours in the fall trolling for walleyes, and I believe him. Maybe I'm a sucker, but he's answered every text I've sent to him and tried helping me troubleshoot things. If it was a melon, I have a feeling he'd just ignore me.

To address some of the questions:

1) New fuel as of June mixed at a 50:1 ratio.

2) New fuel line and primer bulb as of about a month ago.

3) New spark plugs. That initially was what I thought was a problem, because the bottom cylinder was wet and the plug seemed pretty corroded. Replacing the plugs seemed to help, but apparently didn't fix the main issue/s.

4) The gas tank is internal and doesn't have a vent on the cap, however maybe the vent tube is plugged. I'll check.

5) Yes, on land I put it in gear and the prop spins.

I really think maybe I didn't hook the fuel lines up the best. They slid on just fine, but I had an awful time trying to cinch the zip ties tight. It could be they're still loose.

Again, before I touched the carbs, I had no problem running the motor at full steam. It even went down pretty close to idle without stalling. If I got too close or went to neutral, it would sputter dead within a few seconds.

Actually, there was ONE time where I motored across the lake and got to the spot and put it into neutral and it idled like nothing was a matter. I just sat and stared at the motor for 20 seconds as it just chugged along. Then we fished and I tried starting it again and apparently the Germlins were off their union break.

 

[jdinny]

With the engine off, check to make sure the throttle is opening the butterfly in the carb completely at full throttle. Sometimes it can be easy to hook the linkage up incorrectly after removing the carbs. Just an idea

this is exactly how my buddy detected mine, 2 were opening up one was not. pretty easy fix $8 part, has worked since that time flawlessy

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those throttle linkages are plastic. if you store your boat outside in the winter I would really consider looking at that if I were you

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good point eye could be a spun prop too?