Shift Interrupter problems

MarkGinger

Recruit
Joined
Nov 7, 2020
Messages
3
Hi

I have a Faeton 730 Sport with a Mercruiser 4.3 MPI/Alpha One Gen 2. I am having problems with the shift interrupter switch when coming out of reverse. It seems to take to long for the lever assembly to go it to neutral position and engine sometimes stalls. I have disconnected the lower shift cable from the assembly and i can move it in manually and out of gears with ease. Also changed the interrupter switch. Any suggest what to look at next?? Thinking cable that run from control to engine or the shift plate itself.

Tks
 

Grub54891

Admiral
Joined
Jun 17, 2012
Messages
6,071
99% of the time its the lower shift cable. It may shift fine when disconnected but under load it won't. The cable will need to be replaced, they can't be lubed.
 

Baylinerchuck

Commander
Joined
Jul 29, 2016
Messages
2,726
Did you go through the entire shift cable adjustment procedure? @achris has a great tutorial that I use every year on YouTube. The barrel to end of cable adjustments are critical. Good luck.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
On MPI engines, the interrupt only kills half the cylinders, so it shouldn't stall the engine. I suspect you have other issues.

With the drive in neutral, press the interrupt switch and see if the engine runs rough or actually stalls. Also see how the interrupt feels. It should be crisp and quick. If it's 'soggy' and slow, pull the shift plate, strip it and clean and lub everything.

The lower shift cable would almost be the LAST thing I would look at replacing (because it's not cheap, and a PITA job. Do the easy things first, and when you're sure it's not one of those, THEN look at the cable)

Chris.......
 

MarkGinger

Recruit
Joined
Nov 7, 2020
Messages
3
On MPI engines, the interrupt only kills half the cylinders, so it shouldn't stall the engine. I suspect you have other issues.

With the drive in neutral, press the interrupt switch and see if the engine runs rough or actually stalls. Also see how the interrupt feels. It should be crisp and quick. If it's 'soggy' and slow, pull the shift plate, strip it and clean and lub everything.

The lower shift cable would almost be the LAST thing I would look at replacing (because it's not cheap, and a PITA job. Do the easy things first, and when you're sure it's not one of those, THEN look at the cable)

Chris.......
Chris i pressed the interrupt switch and the engine stalls if i keep it held. The interrupt feels crisp. Saying that i took plate apart, clean and and lubed everything. Problem persists. Any other checks i could do before ordering lower shift cable???

TIA

Mark
 

Baylinerchuck

Commander
Joined
Jul 29, 2016
Messages
2,726
Do you adjust the shift every year even if not replacing the cables???

I pull my drive every year so I can check the coupler alignment, gimbal bearing, and bellows, etc. Sometimes I do have to adjust the cables slightly by sliding the pin up to fully engage reverse. If I do any mechanical work to the drive including impeller, etc I’ll always perform the full procedure. With Chris’ video, it’s extremely quick and painless. I go to YouTube to view it.

The shift interrupter switch is made to close when the cables bind to momentarily release pressure on the drive so it slips out of gear. So any binding of the cable including the shift arm on the drive will cause the shift plate to move closing the interrupter. The switch should never close when the boat is running on a hose out of the water, only when the prop is in water.
 
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