Engine Bog's Down when getting on plane....*Updated w/ Video*

[JimBuck]

I've noticed the past few times I've been out that my engine will sometimes bog down while getting on plane. It get's up & out of the water then seems to bog down and I lose a decent amount of power for a few seconds then it seems to pick back up and things are fine again. When it does this the engine makes a different noise and while getting on plane I see a decent amount of exhaust coming from the front of the engine where the tiller handle attaches to the engine. It's a 88' 45hp. Mariner and she does burn a little rich but I'm curious if that is related to the bogging down of the throttle? It almost sounds like it's not getting enough gas to the engine resulting in the engine bogging down.

**Update**

Here's the video, having the sound on helps to know when the bogging occurs...Thanks again for any ideas.

[croixflats]

BE CAREFULL! I had similar symptoms with my Yamy 150 minus the exhaust. Ended up being a bad fuel pump and melting a piston.

[JimBuck]

I just had my fuel pump replaced so I wouldn't think that would be the case....but that's good you pointed it out croix. Cheers. I sure as heck hope it's not a sign that she may be on her last leg. The last thing I want right now is to dump money into an old motor.

[leech~~]

It maybe at the end of cavataing and grapping good water with no air, right at that point?

[croixflats]

I'm kind of going through the same thing on mine again. And I also replaced the fuel pumps. Being worked on by an expert now.

For trouble shooting purposes I was thinking maybe electric like maybe coil. Or fuel, may valve seats or a stuck float.

Oh so many things can be wrong.

I envy and admire those 2 seater paddle boats at times.

[JimBuck]

leech, yeah pretty much. I've never had an issue with getting on plane but maybe it does happen in the transition from getting up to on plane and only last a few seconds.

croix, I hear ya' man. I'm not wanting to deal with any issues at this point in the season and a 2 seater might be a better alternative....ok, maybe not. But I've absolutely babied this engine and would hate to see her bite the dirt after all the preventative maintainance I've doen this year. I can only think of once where I drove it WOT otherwise I keep her at 20mph for cruising so I think I'm being easy on her.

I'm getting out this evening and I'll post a video of what she's been doing. If you see a guy on Wac. with an awkward acting engine...Stop and say hi! Cheers guys.

[croixflats]

My engine is acting up again and it started out that way again but got progressivly worst even after replacing both fuel pumps. Have in getting it looked at I'll call the mechanic tonight to see if he found anything out and post if any thing he has found out. He does the work on the side and he is slow so I'm not sure how far he has gotten.

[JimBuck]

Many thanks croixflats. Good luck with diagnosing the beast.

[BoxMN]

Jim, we have that motor (82 merc 50hp, but same old "Classic 50") aned it is great motor. I will bet you a million dollars that the gas tank vent is vibrating closed

Check it out. I have helped over a dozen people with the same symptoms, and they are always happy when they find that is the case, ha! I bet that is it.

We put a zip tie under our screw top, to keep it from EVER vibrating closed again, ha!

Good luck, its a great motor and you will love it. It is a thirsty motor though, so always go out with a full tank, and maybe a two gallon spare can

[boatfixer]

Have you tried choking it briefly when it does this? Does it do it suddenly like someone flipped a switch or does it "stutter" and come out of it? The other thing I'd do is hook up a timing light to each cylinder individually and see if you have an ignition problem.

[walleyehawk]

I am not mechanically inclined, but I had this happen a few years ago and took it into the dealership. They gave me a different prop and the problem went away. The only change was the pitch with it going one step down, more power and little less speed. Same diameter.

You take off, everything is going fine and then you just bog down for a few seconds. You give the engine a few words of encouragement. As you get close to plane, it seems to resolve itself if you are lucky. Mine also worsened as load increased, such a passenger weight or extra gear.

With the props with hubs and blades sold seperately, you may be able to experiment. That and maybe balance to load in the boat.

Like I said, not a mechanic, so if I am wrong, sorry. But you might solve your problem with a call to the prop shop.

[croixflats]

JimBuck I was not able to track my guy down tonight. I even sat on my boat waiting for him but no show. I'll try again tomorrow night.

[JimBuck]

Hey guys. Thanks for the replies. I had a pretty good day of fishing yesterday and didn't even think about doing the video of the problem. I'll be sure to get at it tonight.

BoxMN, I'm glad you mentioned that. Currently I'm trying to run my spare tank empty (plastic 6.6 g) and maybe I've got a loose fitting on that tank. I checked the vent and it is staying open. I'll fill up the main tank today and give her a shot.

boatfixer, I have not tried choking when it does this I will give it a try. I've tried priming and my bulb doesn't feel firm when it occurs. When it happens, I let off the throttle a bit and then give it a little more throttle steadily and she slowly makes it on plane. It has been nasty windy the past few times I've been out, could this contribute to the symptoms I'm having?

walleyehawk, I picked up a 16 pitch about 3 months ago and haven't had an issue with getting on plane until now. I've been going solo lately and maybe I'm a little too heavy in the back end of the boat....

croixflats, Thanks for looking into it. Keep me posted on how it works out. I bet seeing her sit like that must drive ya' crazy!

I'll keep you all posted this evening as I'll be out again. Cheers guys.

[FishinMaverick]

I have had this exact same problem and after many hours of carb cleaning and the such.....I checked the fuel pick up line INSIDE the tank and it was rotten...outboard would get fuel when taking off but as soon as she leveled out it would suck air and bog down...........slow down and away she went.....get close to plane and bog down again. By the way it was the same year engine and model!!

[Valv]

Have you tried a compression test ? It will eliminate some basic issues.

[marine_man]

I see a decent amount of exhaust coming from the front of the engine where the tiller handle attaches to the engine.

Have you run this motor on the hose, with the cover removed? To try and identify where this exhaust is coming from? Could be a gasket leak that's not helping things.

marine_man

[Surface Tension]

You said you pumped the bulb but didn't say what happened. Did priming the bulb change the condition? Did the bulb continue to be mushy? White smoke? Is the outboard pumping water? Did you pull the cover and look for water and is there water getting into the electrical?

[JimBuck]

Valv, I haven't given the compression test a go....I'll pick up one of those units after work.

marine_man, That's gonna be my next step after work. I'm gonna switch out tanks (currently running a plastic spare dry) and put the muffs on in the driveway.

Surface Tension,I primed the bulb and it continued to be mushy. Yes I was seeing white smoke when attempting to plane. After looking maybe water has been getting into the electrical the last few times out.

A few questions regarding troubleshooting....

-Can I put the engine in gear with the muffs on? I've always assumed I lose some cooling with just the muffs and avoided it all together.

-In regards to the outboard pumping water. Is the way to check through the TellTail and if it's pushing a steady stream?

Thanks guys.

[marine_man]

A few questions regarding troubleshooting....

-Can I put the engine in gear with the muffs on? I've always assumed I lose some cooling with just the muffs and avoided it all together.

-In regards to the outboard pumping water. Is the way to check through the TellTail and if it's pushing a steady stream?

Thanks guys.

1) Yes, make sure the muffs won't interfere with the prop. You actually get better cooling with the muffs because the water is being forced into the motor

2) The Tell Tale stream check is a perception deal... I'd make sure there's no junk in the grommet / fitting / hose it comes out, and if it's not a good stream at idle or just dribbling out it's time for a waterpump. But, you can't test this on a hose for the reason mentioned in #1 above. You'll need to do this at the lake.

marine_man

[boatfixer]

From the video, it looks fuel related. If it were mine, I'd tee in a fuel pressuse guage and/or a clear peice of hose inline and look for air bubbles. Still the possiblilty of a piece of crud in one of the high speed jets of 1 of the carbs, float level, etc...

[Surface Tension]

Switch out the tank and use fresh gas. Inspect hose and bulb connections. Check fuel line connections to carbs, fuel filter, and fuel pump. Check the impulse line from crank to fuel pump. Being that the pump was just replaced it could be a clamp got missed or not tighten. While your at it check the fuel pump for loose screws.

If all that checks out the fuel pump pressure test or clear tube test for bubbles should be good unless the fuel pump is bad.

The white smoke which I didn't see in the clip, could be just exhaust with a little steam swirling forward from the exhaust relief port. If there is a lot of steam coming from the exhaust relief that is a sign of improper cooling. Could be impeller, or restriction. I'd put it on the muffs and run it. While your at pull the cover off and look for water.

[BoxMN]

You know, that sounds like what my bro in laws old outboard was doing after he replaced the impeller. It finally had pressure it needed, and that in turn blew his seal around the head (??) the part that cools the head. Water leaked through and would get his plugs wet.

We put it on muffs and could see the water squirting around pulgs really easily. It was cheap fix for him, since the bolts didn't break taking it off.

Good luck.

[JimBuck]

Update:

I switched out tanks last night and put fresh gas in the tank and she seemed to run great. There were a few occasions where she seemed to be a little starved of gas but the condition seemed to be improved and didn't bog as drastically. I'm going to pull the cover off and run her tonight and see what the deal is with loose screws, clamps, seals etc. Thanks for the advice guys. I'll update tomorrow with what I find.

[ec30_06]

If fresh gas helped it might not hurt to run some sea foam or fuel system cleaner through it to clean out any gunk from the old gas.

[BoxMN]

One other thing to maybe consider... I had somewhat similar thing with my merc 50hp. When tubing, and turning hard, it would bog. Thought it was bad gas, it wasn't. I ended up trying new hose, that was not it - BUT - i didn't change the end of hose fittings, I used the old ones.

These particular ones were the cheapo plastic ones I got from a cheapo grey hose from big box store. I found soome old original alum and steel ones from Merc, I cleaned them off, put them on a good hose, and that fixed it.

It must have been that the plastic fittings were only tight when I was NOT turning tight. The metal ones fixed that, and now tubes and runs perfect again. So maybe, just maybe, your fittings might be a bit off when getting onto plane or something.

Good luck