my first real boat

[wagn]

Got my first real boat. Nothing huge but great for my needs on ponds and small lakes. The only problem i'm having is with consitant speed on the motor. The dealer checked it all out and everything like compression and stuff is fine, I think it might be operator error. Sometimes when I take it out it will do upwards of 23 mph, but other times i can only get it to do 8mph.

I think that it might be because of something to do with the gasline/tank. If i forget to open little nob on the gas tank to let air in, could this restrict flow and cause the motor to not get enough gas to go consitantly fast?

anyways, any help would be great, and here are a couple of pics.

[TopDog]

Congrats on the new boat!  Does it hesitate?  Does it start right up and stay started on idle?

[wagn]

starts up just fine, and idle's fine. Nothing appears to be wrong to me. Sounds good, runs smooth, but just seems to have a difference in speed. Sometimes it takes off, and sometimes it just chuggs along at 8mph, even with full throttle

[ThomasL]

If you are talking about the vent plug in the top of your portable gas tank,fill with gas,turn vent clockwise to close,pump up primer bulb.Like others do after use open vent cap so tank won't swell like a 200 degree watermelon! ;D

[mdntridr]

Dude that is the PERFECT boat for me!  What is it, 14, 15 feet?  Do you mind if I ask where you got it and how much it set you back?

Back to the topic:  have someone drive and work the throttle and make sure the throttle actuator on the motor has full range of motion.  Might need to take the cover off.  If the motor is carbureted and not injected then having the knob shut may indeed cause the problem.  I can't imagine that this wouldn't be covered in the boat/motor manual.  If you bought the boat new I would hope the dealer would go for a ride with you so you can demonstrate the problem.

[wagn]

that is what i'm talking about. but if i leave it closed while driving the motor will it stop sucking gas into the motor because there is not air coming in. If that makes any sense? or is there something else i'm doing wrong that could be making the speed change so much.

I've tried playing with the trim as well in case that is the problem, but that doesn't seem to be it. Whatever it is, it's driving me nuts. i go out one day and i'm doing 23mph, turn off the motor, troll around and fish, and on the way back i'm only doing 8mph. Or it could be vise versa, starts at 8mph, and then next time it's up to 23. doesn't make any sense to me, What could be causing this?? thanks for any help

[mdntridr]

so does the motor rev all the way up and you just don't go anywhere?  Or do you mash the throttle and and doesn't rev up?  If it revs up but you don't go anywhere, probably a lower unit/transmission/prop problem.  If it doesn't rev up up when you floor it then it's a throttle/air/fuel/ignition problem.

Carbed systems generally use the motor's vacuum to actuate a weak mechanical pump to suck fuel out of the fuel tank and into the carbs.  If the gas tank vent is closed, maybe there's already vacuum in there, and whichever system has the higher vacuum wins, meaning little/no gas for your carbs and wagn goes slow.  FI engines will have a high pressure electric fuel pump that will probably not suffer this problem but who knows......

hope that helps.

Greg

[surfer]

I wouldn't think the vent not being open would cause the 8 mph you are describing. The vent should cause a more gradual shut down as the negative pressure builds in the fuel tank.

That boat looks brand new. I would take it back to the dealer for him to fix. You paid for a working product so it's his problem right now. If you go tinkering under the hood you may break something and void the warranty.

The difference between 23 and 8 and that it's always one or the other makes me think its a two cylinder engine and one cylinder is dropping out.  It could be a loose sparkplug wire or any number of other things that would cause a plug not to fire some times but fire other times.

I hate intermittent problems.  I wish it would break or not break.

[wagn]

it always goes somewhere. It just doesn't get up to full speed sometimes. I think it's not revving all the way up. so it has to be an  air/throttle/fuel/ignition problem. What drives me nuts is that it's not consitant. The only thing i can think of is the vaccumn thing. cause the first time i noticed it, i hadn't pumped up the primer bubble thing, and it went slower. and then the other time that I had trouble i noticed later that i forgot to open the gas tank valve. Hoping that this is the problem. This is my first boat, so i've never really had any experience with outboards. Thanks for everyones opinions and help. What i've got to do is have someone who knows boats go for a ride with me, and teach me to use it. but i don't really know anyone in my area.

[wagn]

yeah, i haven't done any tinkering yet. I think i will have to bring it back to the dealer. but i had him do a check over on the engine before i bought it, and everything seemed fine.

[TopDog]

  Quote

I hate intermittent problems. I wish it would break or not break.

LOL! I hear you!

Here is one more thing to check, Spark plug wires. Make sure they are all set tight and not hanging off making contact sometimes.

Good luck man!

[bassboy1]

Nice boat.  

Your problem doesn't sound like leaving the vent shut.  If you left the vent shut, it will start out running like a banshee, and gradually lose some of its gusto.  I have seen on the lake, where some guy in a canoe with a 9.9 (fun combo right there - that sucker is FAST) kept starting his motor, running a bit, then slowing down, and stopping, at which point he pulled on the motor for a while, and it ran for about 2 minutes then slowed down.  It was quite funny once I told him what the problem was.

Hey Jim, you gonna try to convert him?

[IneedAnewScreenName9886691]

Sweet rig!!  You will figure this little problem out, I am sure of it!  

[wagn]

Thanks for the positive message hydrilla.

Seems that it was the valve on the gas tank. Took the boat out this morning before work, and didn't even allow myself to bring a fishing rod. I took my time to make sure everything was all set and played around with different trim settings, and having the valve open and closed, and a couple of other things to see if i could fix the problem. It definietly looks like the gas valve was it. After letting the engine warm up for a minute i was able to cruise around the lake no problem, and never had a problem with loss of speed.

Thanks for everyones help.