Engine shuts down when shift to reverse

[William Foster]

When shifting 1984 Mercruiser 140MR into reverse engine quits suddenly. I can shift into reverse and apply a little throttle, enough to back the boat slowly. Applying more throttle however results in sudden quit of engine. Worked fine for past 25 years. Just put in water for season. Outdrive replaced 2 yrs ago. Outdrive was not removed for winter. Boat used 52 hrs in 2009. Is this a cutoff switch or a cable problem?

1984 Mercruiser 140MR Engine serial #A343742, Transom Assembly #A354288

 

[Bondo]

Re: Engine shuts down when shift to reverse

Is this a cutoff switch or a cable problem?

Ayuh,.... Welcome Aboard,....
Sounds like the Lower Shift Cable has finally given up the ghost to Me...

 

[Fishermark]

Re: Engine shuts down when shift to reverse

Yep - What he said. ^^^^

When the lower shift cable gets stiff, it takes more effort to push or pull it and the shift interrupt switch stays engaged too long. The problem isn't the switch, but the cable itself. Replacing the cable should solve the problem.

 

[EddiePetty]

Re: Engine shuts down when shift to reverse

........ I can shift into reverse and apply a little throttle, enough to back the boat slowly. Applying more throttle however results in sudden quit of engine........
1984 Mercruiser 140MR Engine serial #A343742, Transom Assembly #A354288

William, before you get carried away replacing parts: isolate the problem component(s).

On the trailer, disconnect the lower shift cable from the shift bracket (do not reposition the barrel nut). Have an assist hand rotate the prop while you push the cable into its sleeve for forward and pull it out for reverse. The cable should move quite easily through its entire travel. If the cable moves freely, check the shift plate and interrupt switch for ease of operaton. The switch plate should return to netural of its own with the switch centered in the slot. If the cable binds or is otherwise difficult to move through out its range, remove the outdrive and operate the lower shift cable from outboard. Be certain to check the slide, roller and especially important, the freedom of the vertical shift shaft. Any accumulation of crud around the vertical shaft or in the void for the slide can contribute to your problem.
Adjust your cable like this: http://www.mercstuff.com/images/shiftcable.jpg

 

[jerryjerry05]

Re: Engine shuts down when shift to reverse

Replace that shift cable.J

 

[180shabah]

Re: Engine shuts down when shift to reverse

25yo lower shift cable - it's due....

 

[bds85466]

Re: Engine shuts down when shift to reverse

I'm in process of doing my lower shift cable -- it looks like the cable is good (getting adequate travel) but the set screw fell out of my corroded linkage!