Home › Forums › Bass Cat Boats › Mercury Throttle sticking about 3/4 throttle
oldtimer57.
I have a 2009 Sabre with a Mercury control box connected to a 2018 Mercury 150 Pro XS that sometimes sticks about 3/4 throttle not allowing to get out of the hole. What is more concerning is a couple times it has stuck in the same place shutting down. The throttle linkage has been looked at, mechanics dont see anything wrong. Not sure where to start looking into this issue. Could it be bad cables? Could it be something blocking operation in the gunnel behind the control box? Does the control box need to be replaced? Any advice would be appreciated.
It could be lubrication or a bad control box.
Where should I try to lubricate, are you talking about lubricating the cables at the control box?
Inside the control box area and after removing the panel and sliding it out.
Heres my diagnostic process for this.(1) go pull the cowl, then disconnect the shift cable AND the throttle cable. Now try the throttle lever and it should offer no resistance at all. If there is any tightness, you are one step closer to the source. If it is free, you need to look at the shift linkage where the shift cable connects. There are a couple of lube points (pretty obvious ones as you can see where things slide over each other) that could be dirty, dry, or sticky. Shifting is by far the hardest effort needed. Not so likely that the throttle linkage is binding but you can take the lever where the cable attaches with the unlock nut and move it full-range. It should move (and probably does) easily. If you feel any roughness, track it down and fix it. You can test the throttle part of the system by pressing the throttle-only button in the middle of the throttle pivot point. That disengages the shift cable linkage and only moves the throttle. If it is easy to move now, the problem is likely in the shift side of things. If it is still tough and seems to be binding, you can focus on just the throttle cable.(2) if the throttle lever misbehaves when not connected, the problem gets more complicated. First, see if you can tell whether it is easy for the first 45 degrees of travel and harder later, or vice versa. When you move the shift/throttle lever, the first 45 degrees of movement is almost all shift linkage, the final 45 degrees of movement is almost all throttle cable movement. So the question now becomes “which quadrant is the problem in?” You mentioned 3/4 throttle which makes it sound like it is in the final 45 degrees of travel. In my 08 classic, the process to get to this stuff is a bit of a pain. Remove the seats, then remove the seat pan (the fiberglass panel that the seats mount to and which covers my fuel tank. Then remove the angle aluminum bracket on the drivers side to give room for your arm. You have to remove the center cover, then the bezel on the throttle (toward the drivers leg) and then remove the three inner bolts (there are 6, three closer to the shift lever shaft that hold the throttle mechanism to the mounting plate, and the outer three that hold the mounting plate to the boat. Get the three inner bolts out, there are no nuts as they screw into the throttle. I then get a helper (still have engine cables disconnected at the motor) to grab those cables and as I reach in over the fuel tank to grab the throttle assembly and try to push it back far enough that I can pull it out over the fuel tank, the helper pulls on the cables to help prevent any kinking.Now you need to take a good look at both cables. If one has a kink, it has to be replaced. You might be able to straighten it, but I would simply replace for safetys sake and to be sure I get back to smooth operation. If there are no kinks, you have to get braver. Remove the cover off of the shift lever. Go slow here as there are some screws/bolts that hold the cover on. Keep it flat so that nothing falls out and lift the cover. Again, being careful, you can now extract the cables. Mark them with tape so that you keep them straight (throttle vs shift). You can now determine if one of the cables is defective in a place you cant see (which is most of the cable, of course…). If you look at the control, there are lots of friction points inside that should have something like 2-4-C grease on em. With the cables removed, you can carefully put the throttle lever back on and test the movement. Should be very smooth since there are no cables attached.Somewhere in all of that stuff you have a problem. And I have helped folks more than once where everything looked good when at this point, but add some drag from the cables and the shifter can get harder. Or add some resistance from the shift linkage on the outboard and a cable gets stiff. A kinked cable is sometimes easy to move with no resistance on one end, but connect it and the kink suddenly becomes very hard to move.Usually a sticking throttle at a constant place suggests that a cable is bent/kinked. You can eyeball where the cable exits the splash well and goes through the rigging tube to the front of the motor. Somewhere in there is the most common location for a kink. Motor tilts up and down, the jack plate moves the motor, motor might be hung from the flywheel loop to get it off for some reason, etc.The above description applies to MY boat, notice. Mercury has made several flavors of throttle/shift controls, as well as several flavors of shift/throttle linkage in the motor itself. Cables have not changed unless you have a DTS motor with no cables like the v-rod.This probably wont be that hard to fix, but the key is to go slow and be methodical. Our throttle levers ought to be fairly similar since there is one years difference in our boats (mine is an 08). Motor is unknown since mine is a 2014 Pro XS 200, and I dont know how that compares as far as shift/throttle linkage goes.One possible sticking point that is not so obvious. When you remove the throttle assembly, in the middle of it just aft of the throttle/shift shaft, on the drivers side (toward the driver) you will see a small brass unlock nut. This is the friction adjustment. Too light and the throttle will creep back toward idle when you remove your hand while running. Too tight and shifting/throttle can be unnecessarily stiff. Hard to adjust this off the water, so I drilled a hole through the mounting plate (with the throttle assembly OFF) positioned so that I can now just remove the throttle lever and bezel, and then get a 1/4″ drive socket of the right size on it without having to get the throttle assembly out. Why on earth Mercury put that friction adjustment there is unknown. Worst possible place it could be until you drill that small hole. Would not surprise me if this is the issue. Mine is old enough that it is not a real smooth throttle, but it doesnt have any significant binds in it.I can answer specific questions. If you do a google search, you might be able to find a manual from Mercury that covers your specific throttle model #, it will show all of the internals, lube points, etc..There are other possibilities if someone worked on the boat around the time this started happening. I once helped a friend that had just installed new battery boxes and batteries. He had one group 31 battery and it s box screwed in nicely. With BOTH cables under the box and getting crushed by the weight and the screws holding the box in (aluminum box). So you might get to go all the way and pull the cables out. Fortunately they are not really that difficult to remove since they are pretty stiff and go all the way back down the side to curve into the splash well and rigging tube.After reading all of that, you might decide that the sticking is not really that much of a problem. 🙂 But I would certainly fix it as not being able to get to idle quickly can be a serious accident waiting to happen.
Thanks oldtimer, I always enjoy reading your post. My throttle does not always stick, has only happened 5 or 6 times in the 2 months I have owned the boat. If it sticks while trying to get on plane, no big deal, just will not get out of the hole. If it sticks while coming off full throttle, I have to force it past the sticking point which represents chopping the throttle which could cause bow hook. I am taking it to the shop for them to replace the cables or the control box whichever is necessary.
That sounds like it needs fixing. The throttle mechanism is a two-stage deal. As I mentioned, the first 45 degrees is all about the shift cable, the second 45 degrees is all about the throttle cable. There is a complicated cam arrangement inside that makes this happen, and in that “transition area” which is about 45 degrees forward or backward, one of the cams is slowing down and the other is speeding up. Perfect place for resistance to show up.Personally, Id bet on the throttle mechanism itself having an issue, as kinked cables are usually a full-time problem, not intermittent. One other quick idea: check the cable adjustments. You can look up shift cable centering online. This needs to be right so that the shift effort kicks in at the right place. Basic idea is to disconnect shift cable, go to WOT then back to neutral and mark where it stopped. Then go to WOT in reverse and back to neutral. Mark again. Take one half of the difference in those two marks, and line up the “center mark” on the shift linkage with that mark you just make, by adjusting the barrel nut on the shift cable. That causes a lot of issues as cables stretch and can lead to difficulty in moving the throttle lever as well…
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