Merc 228 stall while docking

[widowsson]

1978 Cruisers VillaVee. Twin Merc 228s (305 chevys). Had water in 1 gas tank, resolved that. Switched to other tank anyway just to troubleshoot. Rebuilt carbs (professionally). New coils. New fuel filters. New raw water pumps. New ignition switches. Four batteries, wired in two banks with new switches.
Boat starts and runs well, even at WOT. She will keep a dead low idle under 800 rpm.

Until I try to dock her...

While docking at low idle I lose one or both engines. Usually port though. They start right back up in neutral, but die again when I put her in gear.

I have a mech working on her. He seems to think it is a voltage issue. He is ready to replace wiring harnesses.

Any old salts dealt with a similar issue? Before I start spending cash on an easily resolved problem?

 

[pole position]

Re: Merc 228 stall while docking

Does this boat have outdrives? If so, it sounds like the interrupter switches need adjusting. The switch breaks the ignition for a split second to let the drive change in and out of gear.

 

[widowsson]

Re: Merc 228 stall while docking

No, these are straight inboards. Do they have a similar switch?

 

[Gene70]

Re: Merc 228 stall while docking

Pole Position is right. Sounds like you need to replace both kill switches and adjust porperly according to manual. This is something you can do using an aftermark service manual.

 

[EddiePetty]

Re: Merc 228 stall while docking

Being as these are direct drive and NOT I/O, forget about the shift interrupt switches!!!!
Sounds to me that these 'professionally' re-built carbs have not quite been adjusted to your needs. Please check that the idle mixture isn't just a tad too lean and that the idle speed, after the engines have warmed hasn't dropped quite a bit from your reported 800 rpm's.
As a last resort, have your mechanic fit each carb with a "Dash Pot" to ease the throttle back to idle if all esle fails.

FWIW, Ed in 'ol Virginny

 

[jtybt]

Re: Merc 228 stall while docking

Yeah, May need the low speed air screws adjusted on the carb

Best is to adjust with vacuum gauge but old timers can do it by ear.

Get timing to recommended and turn in screw til it falters and back out til it falters. Correct position is somewhere in between at highest idle. Re-set idle to recommended RPM and do other screw. With vacuum gauge, you set it to highest vacuum. Go back and check first side.

Turn screws in small increments to let idle adjust to new setting.


Then do other engine.