Still dumbfounded on 125 force

[familyfun]

I have a 1988 125 force on a 1988 bayliner 1800 cobra that I just bought this year. I am still in the learning process of outboard motors or well boats in general. I got it out on the lake a few weeks ago and could only run with the cover off, I put the cover on and it would die. If I got the boat idleing along I could put the cover on and it would run WOT, pull into neutral it would idle for a few minutes, try to go and as soon as the gears would engage it would die. Cover off ran just fine no issues. I was told maybe exhaust was filling up in the cover and chokeing out the carbs from either the bellow going out to the pee holes or up from the l/u. I pulled the l/u and replaced the impeller, seal in the housing and the seal on the water tube going into the housing. Put a grommet with some sealant were the water tube comes down into the l/u. Put it in a tote and it ran fine, no problems with cover on and cover off. Took it to the lake and i'm back to square one. Cover off runs okay as soon as we put the cover on it died. Plus, even with the cover off I really had to give it the throttle when engageing the gears or it would die. So, new impeller, new seals and gaskets in l/u, plugs have about 4 hours on them, fuel filter cleaned, and fresh gas. Why won't it run with the cover on? Where does the engine get it's fresh air from? If I push the throttle all the way forward (leaving it in neutral) should the carbs be wide open? Right now if I push it forward the carb linkage don't engage until about 3/4 of the way WOT then in only moves a very little. I know this is alot just trying to get it going before memorial day weekend.

Thanks in advance,
Josh

 

[familyfun]

Re: Still dumbfounded on 125 force

Don't know if this will help any at all but, this was the first day I took it out
http://www.youtube.com/watch?v=O7xRFhq_d2Q

 

[reelfishin]

Re: Still dumbfounded on 125 force

The exhaust boot is a definite possibility but mine had an issue like that but what I found was that with the cover on, the ignition wires would short out as well. I had replaced the boot on mine, rebuilt the carbs, and replaced the coils and fuel pump before getting it to run right. I'm still messing with my tilt and trim unit.

 

[familyfun]

Re: Still dumbfounded on 125 force

I did check the bellow in the mid leg, is this the exhaust boot? The bellow seems to be fine. Really wish I took the video camera today to get footage of where the exhaust is flowing up from.

 

[Frank Acampora]

Re: Still dumbfounded on 125 force

The engine inducts air from up high on the rear of the cover and below the bottom carb. Under the carb you will see a cast aluminum horn about 6 inches wide and an inch or so thick. It will be about two inches high. This is the splash guard for the intakes located under the lower pan right behind the steering snout.

You have a fine running engine and your problems are ALL psychological (Try spelling that at 11 PM). LOL

Actually, your video was interesting in that your camera seems to be strobing the flywheel and it appears to be turning slower than it actually is.

Here are several suggestions:
If your boat has a tach, be certain that idle speed IN FORWARD GEAR is about 750 RPM. Less than that and the engine will tend to stall. The screw is on the timing tower and uses a locking nut to keep its setting. Many people tend to lower the idle too far in an attempt to reduce the noise when put into gear. More about that later.

Before resetting it though, check the spark plugs and clean or replace them. They are surface gap plugs and tend to foul easily. The ignition on these engines works very much like a magneto in that it produces a less powerful spark at slow speeds than at high. So: A marginal plug will fire quite well at high speeds yet misfire at idle. The first signs of dirty or fouled plugs is either hard starting or poor idle.

Don't even be tempted-- If you mess with the carbs, I will come out there and smack your face- Carb adjustments are usually the last thing needed and can only cause more problems. Your engine sounds fairly well adjusted so don't mess with them.

It is common for the idle relief bellows to either crack or to not be seated properly in the tapered set in the rear shroud. When this happens, exhaust will fill the cover and strangle the engine. You did not mention checking the bellows. It is the black rubber boot below the cylinder head, running between the inside engine leg and the rear shroud. It is slightly difficult to get your hand down there to jiggle it, but it can be done. To closely check it though, you must remove the rear shroud. You must remove the six bolts in the front of the shroud and the six or eight inside the lower pan. Then, you must pry the shroud out because there are two roll pins on the bottom, Just slide it straight back off the rubber seal and the bellows will be visible and accessible.

If you disengage the shift by pulling out the control handle or pressing the center button, There is a neutral interlock stop that prevents you from opening the throttle more than a crack. There is also a spring loaded quick connect on the throttle cable that prevents the throttle from opening until the shift cable has engaged the selected gear. The net effect is that in start/fast idle, you can advance the throttle quite a bit before the carbs open and then, they will only open enough to allow the engine to operate at about 1500 RPM in neutral. Similarly, with the shift enabled, you should be able to advance the throttle about 1/4 to 1/3 of its travel before the engine speeds up. When shifting into gear, do it quickly since there is no clutch to slip. Trying to ease it into gear will only wear the drive dogs. You would normally hear a modest "clunk" as the drive dogs engage.

 

[familyfun]

Re: Still dumbfounded on 125 force

Alrighty, I pulled the rear shroud off and this is what I found out. The bellow is in good shape no cracks or tears. The part i'm curious about is this; in the pics attached the one with the bellow where is this tube supposed to go? It looks like it is supposed to go into something but is was just sitting in the bellow. In the other pic is where the bellow goes, does this look normal? I know the pics aren't the greatest it was starting to rail again.

As far as the tach, it doesn't really work the greatest so not sure what the RPM is at idle or when I engage the drive.

Frank, i'm going to adjust the carbs just so you have to come out here and slap me, it would be worth the pain just to have you here so I could learn from a master.

 

[pnwboat]

Re: Still dumbfounded on 125 force

The plastic tube is a stand off tube and does not belong inside the bellows. To put it into place you have to remove the power head. There's two of them. They snap into two holes inside the exhaust tube cavity in the lower end. As they age, the plastic gets old and brittle and they don't stay in place very well. I don't believe they're absolutely necessary. You can't find replacements for them anymore so you don't have much choice anyways. Leave it off.

There should be a tension clamp that holds (and seals) the large opening of the bellows on the lip of the hole that you show in the second picture. Clamp goes around the outside of the big end of the bellows. The spring in the the bellows pushes the small end against the indentation of the rear cover that you removed.

 

[Frank Acampora]

Re: Still dumbfounded on 125 force

The spring clamp tends to eat through the rubber so when you replace the bellows use either a large nylon zip tie or a screw on clamp. Neither needs to be killer tight since the tabs on the leg casting will hold the bellows in place once it is compressed over them.

While you have the bellows off,check the other end. There is a white plastic fitting that the spring bears against and sometimes this plastic melts and deforms.

The plastic tube? I had one do the same thing and in my lazyness, trying to remove it without disasasembling anything, it dropped into the engine leg. Been there for 2 seasons now with no apparent ill effects.

I did not want to mention it before for fear of convincing you to mess with the carbs: In the video, your engine does display a bit of low speed roughness which MIGHT indicate a slightly rich condition. Since you seem set to adjust them anyway, start at 1 1/4 turns out from lightly seated and in 1/8 increments go both ways until best idle is found. (This is abbreviated--use the manual). Then, take the boat out and give it full throttle acceleration from a dead stop. (Hole Shot). If the engine barks and runs rough then clears itself and accelerates, it is too rich. Lean 1/8 turn at a time. If it sags and/or almost dies then starts to accelerate, it is too lean. go 1/8 richer until it accelerates smoothly. The engine should accelerate smoothly through all speeds on the hole shot. HOWEVER: The four cylinder engines seem to like to run best at about one turn out. Certainly, leaner than 7/8 turn out will be asking for trouble so in any case do not set the needles leaner than that.

 

[familyfun]

Re: Still dumbfounded on 125 force

Well, I don't really want to adjust the carbs but if worst comes to worst i'll try that. I just wanted to get you out here to help. LOL I'll remove the little tube and put a hose clamp or zip tie on the bellow. As far as for the white plastic fitting, uumm, it wasn't present and accounted for.

Any ideas while it is starving for air when I put the cover on?

Ran it in a tote with water about 4 inches below where the l/u goes into the midleg, cover on no problems. Put it in the water were the water level was much higher and it really didn't like it at all.

 

[Frank Acampora]

Re: Still dumbfounded on 125 force

If the plastic fitting were not there at all, the spring would protrude through the tapered rubber opening and you would know. Perhaps I was incorrect in describing it by the original color of white. Sometimes (many) the plastic discolors from exhaust and looks like part of the tapered end of the bellows.

I believe that in a previous answer I described the bellows as part of the idle relief system. This simple system is necessary for proper idling.

The exhaust vents under the water. At low speed or idle, or anytime the engine is sitting low in the water, because the snout is deeper in the water, backpressure is too high, exhaust will blow back into the cylinders and the engine will not run properly. The idle relief is a set of vents that lets part of the exhaust out through the bellows and the back two holes above the waterline, keeping the engine idling smoothly and preventing stalling. That's why you see smoke venting from those two holes instead of just water.

So, if your engine does not like sitting deep, you may have a clog in the system. Unfortunately, the vent holes are difficult to get to and see without disassembling the engine. Unfortunately, at this point I do not have a recommendation except trying to use a garden hose and pump water in through the opening the bellows sits over in the hopes of clearing a clog. That's a Hail Mary move though.