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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 15351
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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I figured I would ask you since you have been helping me so

This answer was rated:

Hi Jason! I figured I would ask you since you have been helping me so well right along. I got the boat in the water today. When I put it in reverse it "idles"in reverse fine. If I go to give it throttle, it kills the engine. In forward, no problems. Is there a limiter on this boat? Why would it be fine forward but not backward?

Hi Charles, Jason here. Disconnect the shift interrupt switch on the shift bracket, and let me know if it does the same thing or not.

Customer: replied 1 month ago.
Ok. Have no idea what you r talking about. Lol!

The switch is located where the 2 shift cables come together on the shift bracket on the engine. Do you know where the shift cables are located on your motor?

Customer: replied 1 month ago.
I would have to look. I'm not there. Heading there soon. I docked it. I'm sure I will see it. What do I do with it?

The shift switch is a small little micro switch that is mounted on the shift plate. It will have a little metal arm on the end of it that contacts some linkage on the shift plate assembly. Also on that switch will be 2 small wires. Disconenct either wire (either one is fine) and just tape the wire up so it can not accidently touch anything. Once disconnected try to duplicate the problem and let me know if it does the same thing or not.

Customer: replied 1 month ago.
Understand. Will give it a try soon and let you know. Thanks

You bet.

Customer: replied 1 month ago.
Ok. If this is what you were talking about it didn't work. I took the one top wire off.

Yup that's it. How does the engine do in forward gear, does it make at least 4400 rpms with the boat at top speed?

Customer: replied 1 month ago.
Sorry. Can't answer that. Just put it in today and it started raining so i took it right to the dock. Noticed the reverse when I was launching. Almost hit another
Customer: replied 1 month ago.
Gunna try and take it out tomorrow after work

Okay let me know what happens tomorrow, and we can take it from there.

Customer: replied 1 month ago.
Sounds good. I know it's not a huge issue but if I need to get outta trouble it won't be there

Okay just reply back once we know what the engine does in forward.

Customer: replied 1 month ago.
Will do. Thanks

you bet.

Customer: replied 1 month ago.
I went out but it was real wavy. No possible way of getting and speed out of it. I'm gunna see how tomorrow is.

Okay no problem.

Customer: replied 1 month ago.
Just keeping ya in the loop. Tomorrow looks hit or miss with t-storms. I'll let ya know if I go out tho

No problem, just post back once you have a result and we will take it form there.

Customer: replied 1 month ago.
Jason. I have not been able to get calm enough water to really get it up to speed. However, unbuoyed rocks destroyed my prop so I have to take it out so I can find the pitch of the prop. Is there any other things I can do while it's out to try and fix the reverse issue? If not, I'll hit ya up when I get it back in the water

Okay you should be able to reply back here now, can you reply back?

Customer: replied 16 days ago.
Customer: replied 16 days ago.
Ok. Your wire removal did work once I disconnected both top wires. Sorry it took so long. I wanna complete this transaction then I have another problem. Ugh! Boats r a pain in the ass!

The disconnecting of the wire was just a test. Give me a minute to explain what the actual problem is.

Customer: replied 16 days ago.

T​he problem the boat has is a worn out lower shift cable.

Here is a brief explanation on how the shift system works.

The boat has 2 shift cables, an upper and a lower. The upper runs from the remote control box to a shift plate, the lower runs from the shift plate down to the drive. And they connect on a shift cable bracket on the motor.

Also on that bracket is a shift interrupt switch. This is what you disconnected.

The way it works is that (or supposed to work) that you can shift from nuetral to either gear no problems. But when you shift from either gear position back into nuetral, the upper cable will cause the lower cable to drag, and the lower cable activates the shift interrupt switch. The switchs job is to momentarily "stall' the engine for just 1/4 of a second. This releases the tension on the clutch and allows it to disconnect from the gears in the lower unit. Once the clutch is disconnected fro the gears, the drag on the lower shift cable is go, and the cable then snaps back into place, deactivating the shift interrupt switch. This whole thing is a bit of a process, with many things happening at once. But the overall process takes about 1/4 of a second. The engine does not actually stall, it just looses spark for a moment and then catches itself very quickly. So it should bog and then catch, every time you shift from an in gear position to back into neutral, when the boat is on the water. (the system does not work when running the engine on the garden hose)

So when you stall, it is because the lower shift cable is worn out, and causing a bind in 1 direction, and holding that shift interrupt switch open to long, causing the engine to stall. The cable is a wear and tear item, and on average, last about 5 years before needing a new one. But having it replaced will take care of this problem. Once replaced, you would hook up that shift interrupt switch again, and the sterndrive will shift smooth as silk.

I think that should do it. But I work for tips so I do want to make sure you are happy with my service before you go. If you had a further or more specific question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.

Questions do not close out, so if you have to come back later on with follow up questions to the issue you still can even after doing a rating.

Thank you

Customer: replied 16 days ago. this something I can do myself or does the boat have to come back out of the water? And, it seems like this is also causing the problem I have now. It gives me a hard time going in and out of gear in occasion....make it difficult to dock. Seem right?

the boat has to come out of the water and the sterndrive has to come off in order to remove and replace the cable. There is 1 special tool you have to buy but it is not overly expensive. This would cause the shifting to be difficult, especially when trying to shift back into neutral.

Jason and 2 other Boat Specialists are ready to help you
Customer: replied 16 days ago.
Shit. Ok. One more question. Is there a repair manual out there for this? Something with part numbers and such? Can't afford to have it done so I have to fix it myself. Thanks

What you would need is Mercruiser service manual #6. It is not something I can just give you here as they are owned and Copywritten by Mercury marine. However, if you go to google and simply type in as a search "Mercruiser service manual #6" you will likely be able to find a copy to download.

Customer: replied 16 days ago.
Ok. I'm sure we will chat again! Lol. Make sure you got paid. If not let me know.
Thanks Jason

Everything looks like it went through okay, thank you.

Customer: replied 16 days ago.
Good. I need the Manuel from 86 right or will other years work as well?

Y​ou need service manual #6, that is what covers your sterndrive.

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