Replaced outdrive Mercruiser alpha one gen one stalls going into reverse

[moonrakercat]

Hi Guys - hoping for some input - I have a 79 thundercraft with a 228 mercruiser i/o engine -I just I swapped the old mc-1 outdrive (lost the gears) for a rebuilt alpha 1 gen 1. My old outdrive had 14.5" 17pitch prop - the alpha one has a 15.5" 18" pitch prop. The boat starts & runs fine - goes into forward gear fine - and drives fine - but if I'm going forward very slowly then put it into reverse - it stalls - I need to quickly restart the engine (when it's in neutral) - then put it in reverse - it works ok then. It does not seem to stall when going into neutral from forward - just when going into reverse directly from going forward - ie when I'm docking. The idle rpm is good at 650 - is this an ignition interrupt switch problem ??(where is this) ? I never had this problem last year with my old outdrive.

I should mention that when I'm at the dock and need to back the boat out into the channel I have no issues - it goes into reverse fine - backs out - then I put it in forward and away we go - it only stalls when being shifted from forward into reverse.

I plan to switch the prop back to the 14.5" and see if it makes a difference - although I don't think it will. And possibly bump the rpm up a bit to see if it helps.

Any ideas / input will be appreciated.

 

[dubs283]

It's not a shift interrupt switch issue, at least the switch isn't the problem

Most likely your issue is a mis adjusted lower shift cable or the cable is old, worn and binding. Common issue.

The cable is binding and engaging the shift interrupt at the wrong time. There is a good write up about it in the stickies.

You need to do some troubleshooting and reading to understand the system.

Don't bump up the idle, you'll only cause more problems by doing that. Once you've figured out the shift issue you may want to perform a tune up?

 

[moonrakercat]

It's not a shift interrupt switch issue, at least the switch isn't the problem

Most likely your issue is a mis adjusted lower shift cable or the cable is old, worn and binding. Common issue.

The cable is binding and engaging the shift interrupt at the wrong time. There is a good write up about it in the stickies.

You need to do some troubleshooting and reading to understand the system.

Don't bump up the idle, you'll only cause more problems by doing that. Once you've figured out the shift issue you may want to perform a tune up?

Yes I just read the sticky - thanks ! - good information. And I won't bump up the idle - I understand now.

As the outdrive is completely different - I'm hoping it is just an adjustment required on the lower shift cable - and not a replacement - the cable seemed to be fine when the outdrive was off and I was shifting it then. I'll see if I can find out how to adjust it.