Engine trouble

F

flapbreaker

New member
I have a 90hp Honda that only has 44 hours on it. I've had the 20 hour service done. Took the boat out today for a little crabbing and the darn motor wouldn't run right. First off it was stuborn to start but I thought that maybe I hadn't squeezed the bulb enough. It seemed to run a little ruff at idle but then did ok when it warmed up abit. Now the real trouble is when it's in gear the rpm's jump around by 100 or so and when I tried to give it a little throttle it just didn't want to do much. I could get the rmps up around 3500 -4000 but could only go about 8 knots or so. Again the rpm's while under way would jump around. It was like the motor wanted to take off but couldn't. I think it's getting enough fuel as I could almost kill it by hitting the choke while underway. I guess it could be bad gas but the kicker ran fine on it. If it's not in gear I can run the rpm's up without much rpm fluctuation.

The only things I did to it since it's last use were.... I took the prop off just so I knew how. I took the spark plugs out and they looked good to me. And since it was having trouble starting it I pulled the choke knob out on the main while starting just to see if that would help.

Any idea's?
 
flapbreaker-

It does sound like bad gas/carburetor jet obstruction at first hand.

With only 44 hours, your tank and fuel lines ought to still be very clean, but if you get a bad batch of gas, that doesn't matter. If the new E10 (10% alcohol) mix is new to your area, it's quite possible that it would bring a lot of stuff up from some old supply gas tanks. The choke can kill the motor (or nearly so) regardless of the condition of the engine when applied to a warm engine.

Another fuel mix problem can occur when a small air hose in the fuel system is accidently knocked loose, causing funny and variable mix problems. BTDT.

Check also to see that you got all the ignition wires on tight at both ends, and that the torque on the plugs was reasonable. Crossed wires? Really running on 2 cylinders?

Others will undoubtably have more suggestions!

Good Luck!

Joe.
 
Here's my two cents worth, which will help you if you've got contamination (probably water) in the fuel.

First, turn the fuel selector valve to "off", and drain the racor filter by unscrewing the bottom fitting. I don't know how your boat is configured, but this filter will be in the fuel line somewhere between the tanks, and the motor. If there's room, drain it into a plastic container, so you can see if there's water in the fuel. If there's not room for a catch container, drain it onto a rag or disposable diaper. Be careful with any sparks or other ignition sources. You can do a quick, brief smell test to see if what you drain onto a towel or diaper is straight gas, or a gas-water mixture.

Next, drain the carb bowls. To do this, remove the motor cover, locate the 4 carbs on the starboard side, arranged vertically, and then locate the bowl drain screws, which take a flat bladed screwdriver, and are located one each, on the bottom of each carb bowl. The drain screw is near the lowest point on each carb float chamber, and is not to be confused with the pilot screw, which is near the top of the carb, seated in plastic, and usually marked with a paint at the factory to reveal any subsequent attempts at adjustment. Don't mess with these guys. Crack the carb drain screws until gas drains, then pump the primer bulb until fuel stops flowing from the carb drains. That is, pump out the bulb through the drain screws. Then, close the drain screws. There's a filter inside the motor cover, but with the low hours you have, it's not likely this filter is contaminated with with anything other than water, most of which would have been removed when you pumped the primer bulb out through the drain screws, or which will later work it's way back down to the racor bowl as fuel seeps back through the primer bulb's check valve.

Finally, make sure the drain on the racor filter is closed, and turn the fuel selector valve to a tank with good gas, by which I mean, recently purchased, and stabilized. Pump the primer bulb until the carb bowls are full, and the bulb gets firm. Check the racor for leaks, and for any water in the bottom of the filter bowl. Drain a bit of gas from the racor, and be sure it's pure. If not, you've got more contamination in the tank. Check the carb drain screws for leaks, then put the motor cover back on, and see how the motor runs.

It's a good idea to stabilize all gas, even if you're going to burn it the same day.

Let us know what happens, and good luck.

david
 
THanks for all the ideas.

I did double check the prop. It can't spin since the shaft has slots. I didn't know if I could over tighten it though. DIdn't see signs of wear.

I do have a water fuel separator with a clear bowl. I didn't see any water. Also the kicker motor is plumbed off the same fuel separator and ran just fine. It still could be bad gas as it's over a month old and I might of forgot the stabilizer. Maybe the kicker motor isn't affected by the bad gas for some reason?

Maybe I'll just fill the other tank with some good stuff and go run it. That would probably answer a lot.

If it is bad gas would adding stabilizer now "freshen" it up at all? (I'm affraid I know the answer to that :wink: )
 
If you find your gas is ok....I would take Joe's (Sea Wolf's) advice:

Check also to see that you got all the ignition wires on tight at both ends, and that the torque on the plugs was reasonable. Crossed wires? Really running on 2 cylinders?
Click to expand...

Also, as to Dirty Carbs, if you apply choke while the gas is applied and the motor seems to surge, continue till it almost chokes the motor down and repeat a few times. This will in some cases blow the contamination out of the carbs if it is small enough.

I have had both of the problems above and solved both with the help of my dealer, Three Rivers Marine. Both give the same symptoms as you describe with your motor.

Good Luck and let us know your results.
 
flapbreaker-

No, adding stabilizer after gas has gone bad doesn't reverse what's already happened and the gas molecules broken down into "bad guys".

But gas that is a month old should run just fine. Belive it or not, Chevron has said that it's gas is good for up to a year after purchase!

The clear bowl is a good sign.

Must be something else, but trying the other tank is a good idea.

Check the ignition over again. Did you do anything to clean the plugs and perhaps short them out? Could there be water inside the ignition system?

Could you have bent a fuel line over and restricted the supply? Did you disconnect and reconnect the fuel line?

Dave (Oldgrowth) will crucify me and send Dave S to spray me down with fire smothering foam, but I've actually gone out with the motor cover off, put the throttle down in gear ( on an open lake), then used a can of ether (starting fluid) to spray into each carburetor secquentially to see if it was running lean.
Easily shows whether gas mixtures are lean. Best to do with a friend, though I've done it alone! *

*Disclaimer: Don't try this at home. Professional death-wish driver/mechanic used in stunt demonstration. :lol:

Joe
 
A "clear" bowl under the fuel/water separator doesn't tell you much of anything, if you're already experiencing problems with the motor running. The bowl has a slight color tint, making it very difficult to see whether it's totally full of fuel, or of water. What you're really looking for when you inspect the bowl is a separation line between water on the bottom, and fuel on the top. But, if the bowl still has a visible layer of fuel on top of the water, you probably aren't yet having problems at the motor, because the water is collecting in the bowl. If that's the case, just drain it off, and you're set to go. The motor begins to act up when the filter bowl can't hold any more water, and water has displaced or is in high concentrations in the fuel in the rest of the "downstream" part of the system. In that case, there is no visible separation layer at the filter bowl.

So, if the bowl is clear, and you're having problems at the motor, drain the bowl, and see what comes out. If you get it in a container, you can either give it a sniff, or just put a little water into the container after you've made your collection from the filter bowl. If the water you add goes right to the bottom of the container, and gives you a fuel/water separation line which wasn't present, you know the bowl was full of gas. Otherwise, you know that you have just added water to water, and that you need to do some draining and purging of the filter bowl, and of everything downstream.

Keep us posted.
 
If it was my motor I would first suspect one or more cylinders are not firing. After running it for several minutes you are bound to have at least wet, if not fouled plugs in that/those cylinders. Pull the plugs and look. When you find the wet/fouled one look for problems with that cylinder. First check would be spark at the plug. Check the spark plug wire. Then fuel. Check the fuel in the bowl and see if it is really there and if there is any water in it. After that it would be mechanic time for me. But at least you could tell him what you found and give him a head start.
 
I decided to pull the plugs and look at them even though they looked ok several weeks ago and hadn't used the boat since yesterday. Well, I think I found the problem. One of the spark plugs was black. But the most interesting part is that there was absolutely NO GAP. The end thingy looked like it had been bent. I'm sure it wasn't creating much of a spark that way. How on earth did that happen? I suppose it's possible that I dropped it the last time I pulled them out and maybe it landed just right and bent the spark wire (not sure what that thing is called)? I'm assuming there's no way the engine could bend it? Anyway I'm hoping it's just the bend plug and not some cylinder problem.
 
A bent electrode would do it. Laws of nature require dropped spark plugs to land on their electrodes. Kind of like buying parking at seattle city parks. They sell 2 nights for $19. But the machines only handle in $5 increments. The city of seattle is also governed by laws of nature. Re-gap and I would bet your problem is solved.
 
Flap,

Sounds like you found your problem, but you can have a spun prop, too. If you hit something, the prop can spin on the rubber hub between the splined fitting and the prop itself. One way to check is to pull the prop, put a scratch across the inboard end, then check to see if it acts up again. If the scratch is misaligned, you may have found the culprit.

Regards,

Steve
 
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