Mercury XR6 150hp won't go into reverse

bretmoua

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Mar 30, 2012
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24
Ok, so here's my problem. The last time I used it during the summer, I noticed that my boat was not going full speed when I have the throttle all the way down. Heck, it won't even pick up speed and was going at about 5-10 miles an hour only. So being frustrated, I thought it was the carbs that needed to be rebuilt since I haven't done it for about 5 years now. So I rebuilt all 3 carbs and after installing the carbs, I go to start up the motor and I noticed that the motor revs up to 3500 rpm at idle. So I quickly shut it off as that's not normal. I moved the throttle lever to reverse but it's stuck and won't go in. It goes into forward position fine but won't engage in reverse.
Here are my questions:
1. What's causing my motor to rev up to 3500rpm at idle? I've doubled even tripled check my work on the carbs and there are no air leaks.
2. Does my shifter and throttle cables need adjusting?
3. Why won't my lever go into reverse?
4. If my cables need adjusting, how?
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: Mercury XR6 150hp won't go into reverse

Do you have a FACTORY service manual?

Carb linkage MUST BE adjusted with all carbs fully closed. Extreme care must be used when adjusting the linkage between the carbs as it is possible to skew the adjustment while tightening the set screws and cause one carb to hang slightly open and raise idle speed.

Shifting may be anotther thing, were you trying to shift with the engine OFF? If so then someone needs to be turning the prop as the engagement dogs can colide and not allow the shift linkage full travel, making it feel like the control arm will not move far enough and bind.

Deal with the carb linkage first, once the motor starts and idles then check shifting again.
 

bretmoua

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Joined
Mar 30, 2012
Messages
24
Re: Mercury XR6 150hp won't go into reverse

Do you have a FACTORY service manual?

Carb linkage MUST BE adjusted with all carbs fully closed. Extreme care must be used when adjusting the linkage between the carbs as it is possible to skew the adjustment while tightening the set screws and cause one carb to hang slightly open and raise idle speed.

Shifting may be anotther thing, were you trying to shift with the engine OFF? If so then someone needs to be turning the prop as the engagement dogs can colide and not allow the shift linkage full travel, making it feel like the control arm will not move far enough and bind.

Deal with the carb linkage first, once the motor starts and idles then check shifting again.

I had an online manual which I did not find to be useful at all so I deleted it already. Charlie, so what you are saying is that all the butterflies must be closed before I attach the linkage cables? That's exactly what I did before attaching linkage cables. I have also tighten down all screws again and doubled, even tripled check my work. Just not sure what else could be causing the motor to rev up so high on start up like that.
Yes I was shifting with the motor off. It shifts forward and neutral with no problem. The booger just won't go into reverse.
Now you mentioned that I need someone to turn the prop to engage the dogs to collide? What dogs are you talking about? I'm just not sure what you are talking about at all. Please explain in detail, if you don't mind.
 
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Maxz695

Guest
Re: Mercury XR6 150hp won't go into reverse

I would first disconnect both cables from the engine and shift the sliding bracket by hand in forwards. The prop should lock in one direction and ratchet in the opposite direction. In Neutral the prop should spin feely in both directions, and in reverse it should lock in both diections. Turning the prop or the flywheel may be nessecary to engage full reverse. This sets the clutch dog in sync with the reverse gear teeth. If you cannot push the sliding shift lever on the engine bracket into reverse then there may be a problem with the LU, be it broken shift lock cam, shifter shaft problem etc. You will have to investigate further at that point. Moving on the the idle problem. First make sure the throttle arm is fully back to the idle position. Then check the linkages all the way to the cam that opens the carb lever and make sure the carb lever is not touching the cam. It should be almost touching at that point. Being you took the carbs off do a visual of the butterflies and make sure they are closed tight on all of them as I have even installed them with the little connector that joins the carbs after it slipped off during installation of the carbs. After you have confirmed the shifting is correct and the throttle position is not bound anywhere and not toching the cam you can then attach the shifter cable (Moves first when shifter is moved into gear). put the shifter lever in neutral and put the throttle in neutral. set the barrel into the cup and see if the end of the cable is in line with the pin where the cable locks down on the slider. If not adjust the barrel to the closest fit and then lock the clamp on it. For the throttle cable attach the cable end to the throttle lever making sure it is in full idle position then align the barrel to the cup with minimal distance keeping just the very slightest tension on the cable when inserting the cable bearrel into the cup. Then set the lockdown clamp on the barrels. Re check the shifter again turning the flywheel may be nessecary to get the clutchdog in sync and check the prop for opperation as described above. If all goes well start the engine with muffs or barrel of water and check the idle. some carb adjustments may have to be made at that time good luck
 

bretmoua

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Re: Mercury XR6 150hp won't go into reverse

I would first disconnect both cables from the engine and shift the sliding bracket by hand in forwards. The prop should lock in one direction and ratchet in the opposite direction. In Neutral the prop should spin feely in both directions, and in reverse it should lock in both diections. Turning the prop or the flywheel may be nessecary to engage full reverse. This sets the clutch dog in sync with the reverse gear teeth. If you cannot push the sliding shift lever on the engine bracket into reverse then there may be a problem with the LU, be it broken shift lock cam, shifter shaft problem etc. You will have to investigate further at that point. Moving on the the idle problem. First make sure the throttle arm is fully back to the idle position. Then check the linkages all the way to the cam that opens the carb lever and make sure the carb lever is not touching the cam. It should be almost touching at that point. Being you took the carbs off do a visual of the butterflies and make sure they are closed tight on all of them as I have even installed them with the little connector that joins the carbs after it slipped off during installation of the carbs. After you have confirmed the shifting is correct and the throttle position is not bound anywhere and not toching the cam you can then attach the shifter cable (Moves first when shifter is moved into gear). put the shifter lever in neutral and put the throttle in neutral. set the barrel into the cup and see if the end of the cable is in line with the pin where the cable locks down on the slider. If not adjust the barrel to the closest fit and then lock the clamp on it. For the throttle cable attach the cable end to the throttle lever making sure it is in full idle position then align the barrel to the cup with minimal distance keeping just the very slightest tension on the cable when inserting the cable bearrel into the cup. Then set the lockdown clamp on the barrels. Re check the shifter again turning the flywheel may be nessecary to get the clutchdog in sync and check the prop for opperation as described above. If all goes well start the engine with muffs or barrel of water and check the idle. some carb adjustments may have to be made at that time good luck

Ok, so now I'm able to shift from forward to neutral to reverse with no problem now. But the motor still revs and have high idle...up to 3000 rpm so I shut off the motor again. With the cowl off, I notice that smoke was coming out of the second (middle) carb only. Why would that happen and why did the top and bottom carb not have smoke at all? What does that all mean? Did I do a bad carb rebuild? I have checked all the screws and gaskets and every thing is where they should be nice and tight.
 

bretmoua

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Re: Mercury XR6 150hp won't go into reverse

Should I just admit defeat and take the boat into a shop so they can redo my carbs? I just don't understand why I can't get this going especially after doing a full tune up of the boat myself earlier this year...which included: water pump, thermostats, fuel filter, new gas line and bulb, plugs, and even changed the gear lubes. Taking the boat into the shop is my last resort but if I have to then I will. :eek:( :eek:( :eek:(
If I had to take it to the shop, any idea how much the carb job would be, including new parts and labor? Just a ball park price would be ok so I can start saving. :eek:(
 
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Maxz695

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Re: Mercury XR6 150hp won't go into reverse

Ok, so now I'm able to shift from forward to neutral to reverse with no problem now. But the motor still revs and have high idle...up to 3000 rpm so I shut off the motor again. With the cowl off, I notice that smoke was coming out of the second (middle) carb only. Why would that happen and why did the top and bottom carb not have smoke at all? What does that all mean? Did I do a bad carb rebuild? I have checked all the screws and gaskets and every thing is where they should be nice and tight.

So if all the butterflies are opening equally, and closing fully. (It,s hard to tell sight unseen). There is a possibility of float level in the middle carb flooding that area and allowing to much gas into the cylinder. Also could be the needle seat in that carb is not sealing properly. If there is gas spitting out of the carburetor when runnng it may be a sign of a worn bent or broken reed. I would try to redo that middle carb. Make sure it is closing fully. Make your mixture adjustments out from a light seat to 1 1/4 turns and adjust them equally until best idol. As for a reed problem I would exhaust all possibilities before considering this to be the problem. I don,t think you would need a mech unless it comes worse to worst being a reed issue. (EDIT) If the middle carb is overloading the section from reed to the transfer port cover there is alot of leftover mixin that particular area of the crankcase and seems to be causing the smoking issue. With the carbs exposed so you can see into the troats of the carburetors pump the bulb hard and firm there should be no mixrute in the throats of the carbs through the vents. If you see gas the float is set too high. Also if you have to remove the carbs you can with the ignition off jump the soleniod to turn the engine over with your hand over the intake hole for the carb. There should be no presure coming out of it. only suction to pull in gas. The reeds close after taking in gas closing off the intake port for the carbs.
 

bretmoua

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Mar 30, 2012
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Re: Mercury XR6 150hp won't go into reverse

Ok, so I redid the second carb...basically took it all apart, and put it together again making sure every screw is tight and every gasket is in the correct place. Also redid the float and everything looks good. Put it back on the motor, connected all the hoses and cables...put the carb housing back on...started it up and the same thing happened again. On neutral, the motor is idling at 3000 rpm once again so I quickly shut off the motor. Ahhhh!!!! This is getting so frustrated. What else could be causing the high idling? I realize I had it sit for 4 months but that shouldn't have caused it. I also know my fuel is low, but that shouldn't cause it either. Any other suggestions?
 
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Maxz695

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Re: Mercury XR6 150hp won't go into reverse

View attachment 176032The only other thing that I can come up with is someone here was having this problem on a smaller engine. My suggestion was that the fuel pump had a rupture letting fuel straight into the pulse port through the transfer cover. I can,t see how fuel would enter the engine any other way except for there and the carbs.EDIT I took some pics of a 40 HP transfer cover to help describe what might be happening View attachment 176028View attachment 176029View attachment 176030View attachment 176031 The fuel pump bolts on the outside of the transfer cover if the diaphram is ruptured the fuel gets into the backside of the fuel pump and then finds it,s way into one of engine cylindrs. Because there is gas that gets to the carbs it also is forcing more into the pulse port by force of the bulb. The engine starts but has way to much fuel in one cylinder to burn off and the result is higher RPMS. I believe that if you left it running it would stall out in a bit due to the fuel pump not pumping fuel to the carbs. The section of the intake case that is connected to the pulse port would be the one affected and this may be to the center cylinder and carb. The other two carbs are working correctly forcing the overloaded cylinder to fire the eztra amount of fuel in the cylinder with the pulse port. Maybe a rebuild of the pump is in order. I don,t know if it would be a good idea to run it at 3000 rpm to test this senerio. For a few bucks for the pump kit might be the way to go as opposed to the Mechanic.I believe when I recently had my 70 HP apart that the port was on the exhaust side of the center cylinder I,m not sure but thats where the fuel would go as the pulse comes from there. A simple test to confirm it may be the issue is : pump up the bulb until it gets hard then sueeze it firmly for about 1 minute, If it looses firmness and starts to flaten out there is a leak and it,s more than likely the diaphram. Lastly check the linkage to the trigger if the linkage came lose the timing would be way out causing the engine to rev
 

bretmoua

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Re: Mercury XR6 150hp won't go into reverse

Fuel pump and filter were also replaced earlier this year. I squeezed the bulb til it's hard then held for for a minute and it remained hard still. This is so frustrating. Been tackling this problem for almost two weeks already. :eek:(
 
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Maxz695

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Re: Mercury XR6 150hp won't go into reverse

I added to check the trigger timing base and linkages. If it broke or came loose it would cause the engine to rev. Also what caused the throttle not to engage reverse as this may be and indication of what happened to the idol. I,m thinking at this point that the top carb lever got moved and as a result it sent your timing out of wack. You can try losening the low idle screw and loosening it up to bring the timing way back down to a comfortable idle speed. Timming will have to be reset if this is the issue. On my carburetors (70 HP) the top carb lever has a screw that makes it adjustable. weather it slipped or was moved when rebuilding it is no longer in the correct position. Remove the throttl cable and back off on the low idle screw. This will allow the throttle arm to go back farther than if the cable is attached. The alternative is to remove the top carb and check the lever and reset it to just before touching the cam. The throttle cable barrel will have to be readjusted to compensate the distance from the cup to the throttle arm. This should reduce the timing to an acceptable rate to run the engine.
 

bretmoua

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Re: Mercury XR6 150hp won't go into reverse

Low idle screw on top carb? I'm not seeing it? Whereabouts is that booger?
 
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Maxz695

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Re: Mercury XR6 150hp won't go into reverse

there should be a marking on the side exhaust cover that says idle stop. the screw should be touching it losen the nut then the screw with the throttle cable barrel out of the cup, then adjust the barrel to fit the new adjustment.
 

aussieflash

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Feb 5, 2011
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1,004
Re: Mercury XR6 150hp won't go into reverse

Never try and shift gears with motor off,remember its a dog clutch.
When you start motor do you lift fast idle lever,then push it down when started??Have you taken off air box and viewed butterflies fully closed at idle?
It sounds like a problem in the linkage,could be a simple throttle adjustment as maxz says above.I have a similar motor and same carb setup.The link and sinc procedure is very detailed and needs to be done correctly.You have to find the Mercury Service manual and it will solve most of your problems.
 

CharlieB

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Apr 10, 2007
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5,617
Re: Mercury XR6 150hp won't go into reverse

Check this thread for a factory service manual
Do you need any mercury manuals on pdf format!!! - Page 1 - 309079
Most any of the 150 V-6 carb manuals will detail the carb linkage and synch sequence.

You need to be certain that all of the carbs are fully closed and the throttle cam is not contacting the throttle carb linkage.

Remove all spark plugs, ground all the plug wires, rig a timing liglht on #1, crank the motor and check timing at idle to ensure that timing has not been advanced as advanced timing will increase idle speed. Idle timing should be near 4 degrees AFTER TDC
 

bretmoua

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Mar 30, 2012
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Re: Mercury XR6 150hp won't go into reverse

I'm giving up on this project. Ahhhh....so frustrating to have a boat and not be able to use it. :eek:( I guess it'll be going to a mechanic next year when I get my income tax. LOL Thanks for trying everyone.
 
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