'90 SN Low/Rough Idle - No power

Hi,

I have a 1990 Sport Nautique which has been displaying some odd behavior. Let me start out by saying I'm not very mechanically inclined, but I know many people who are, and am just looking for a few ideas to get them started in diagnosing this problem.

The boat has begun idling very low the past few times I've used it... which is mainly on the weekends (not every day). It's taken me over 1/2 hour to get it started a few times, and when I do, it idles around 200 rpm. Usually it dies and I have to give it a little throttle to keep her at around 800-1000 which is where I think it should be idling. My first thought is that it's not getting enough fuel. I assume this could be from a carb which is out of "adjustment," gummed up, or a clogged fuel line and filter. We will check these things out.

Unfortunately, I had to pull the boat out of the water this past weekend because I was at the mercy of someone who let me use their property to get the boat out. Lake levels are low and I can't get her in/out at the sorry excuse of the public launch. So now I have a dilemma. Not having her in the water is going to make it tough to diagnose the problem and winterize!

I guess I'm just looking for a few obvious things we can inspect while it's out of the water, and if something is glaringly wrong, we can at least take care of it enough to get it running long enough to winterize and deal with the rest next spring.

I should mention that the past few times starting it, I had to actually push the throttle forward while starting it. A friend noticed that there were some tiny particles in the gas cans this last time out. He thought perhaps the plastic cans were decaying and maybe my fuel line or filter is getting clogged.

Also, while trying to pull some wakeboarders out of the water, the boat bogged down so bad on take off that I could barely get them out of the water. When I was trying to drive the boat onto the trailer, it kept stalling because of the low rpm's. Kinda embarrassing :)

I don't believe there is water in the gas, since I go through enough of it to cycle it through... unless there is a way for water to get in the lines AFTER the gas is in the boat???

One other thing to note: After the boat was on the trailer, I was removing a life preserver from one of the lockers on the passenger side. It's in the walkway between the cabin and bow. There were two hoses in the compartment, and one was off. I have no idea what these are for. It's that flexi-hose like you may see on the back of a clothes dryer. One of them was completely off. I don't know if this could be somehow related to the engine problems I am experiencing.

The impeller was replaced this spring. If anyone has any thoughts and suggestions on what I should start looking at first, I'd appreciate it. I thought of replacing the plugs and plug wires, but I'm not sure if I would be experiencing the problems I'm having if those are culprits. Thanks for any advice!

the plastic dryer like hose are venting hoses (for the bilge and for the engine). You have 2 vent inlets in the base of the winshield, on each side, 2 hoses exits eack box and they all connect to the air box located behind the kick panel in the drivers seat..
I don´t think they are related to your problems..anyway try to connect them as in the case of a nose dive the water will enter through there and instead of going to the bilge it will end up in the bow compartment and will wet all the gear stored there...

Mark,
Checking the choke is easy. Remove the flame arrestor off the top of the carb when the engine is cold. The choke butterfly should be closed. As the engine heats up, the butterfly should open.

The fuel filter is a good start but may not be the problem. Usually if clogged/dirty they will restrict fuel at higher RPM's when the engine needs more gas. The idea af the filter is to keep junk from entering the carb!

You didn't answer my question regarding the last time a tune up was done. Do you know?

You mentioned you do have some friends that may be able to help. Have you asked them yet?

IB - You might want to get some training on engine repair/maintenance. These engines are not very difficult to tune.

Most old-school auto concepts apply to marine inboard engines (with a few coast guard requirments thrown in). Maybe there is a adult education course at your local community college, or certainly there is information at your local library.

These boat do require tuning to perform at top level & it is expensive to take it to a mechanic each year.

These guys will help you out, but it will require some basic skills for you you implement.

Good luck, let us know what you find out!

it sounds as if it is starving for fuel, start at the carb and work back checking along the way the accelerator pump, then the hoses, change and inspect the filters, inspect hoses for kinks and dry rot, work your way back to the fuel tank and remove the 90 degree fitting that the fuek hose goes to, that is the anti siphon valve that has a tendency to clog and cut supply fuel.
when checking the carb not running, remove your linkage and pump the linkage and look down the throat and you should see a nice even spray of fuel...not drips. also the tank has a vent that needs to be open to the atmosphere make sure its not clogged or kinked and this can be eliminated by trying to run the boat with the gas cap off (in the drive)
it does sound like a fuel issue, and a good mechanic should be able to get you straightened out