Mercruiser 4.3 adjustments

Kewen300

Cadet
Joined
Aug 9, 2020
Messages
23
So I was able to take the boat out last night 1987 mercruiser alpha 1 gen 1. Started up fine. Let her sit for a couple min then put it in reverse from the dock. The barely went into gear when the motor went full throttle. So get it out on the water and try to get it through its paces. When increasing the throttle the boat felt labored and bogged down at full throttle like towing a car up a hill. Didnt top out at speed the last motor had in it. So I continued through its paces making couple adjustments to the timing and throttle to try and get it right. Was headed back to dock go to put it into neutral to make an adjustment and she died. Wouldnt fire back up again. After a few min of trying she fired then died again when I got closer to dock and put back in neutral to slow the pace and try to put in reverse. Didnt want to start again in water. The thermostat said about 150ish all day but the risers were hot enough I couldnt keep.my hand on them for.more than a couple seconds. Thought I may have been out of fuel. Load the boat up and get it home pop the gas line off the pump had fuel, reattach and try to fire. After about 5 cranks of starter she took right off. I'm pretty stumped as to where to go and what adjustments to.make. any and all advice is welcome
 

Rick Stephens

Admiral
Joined
Aug 13, 2013
Messages
6,118
First thing to do is pull the flame arrestor off and hold the choke plate open, have someone pump the throttle while you look and see if you get squirts of fuel from the throttle pump. No squirt either means the carb is out of fuel, my guess, or the pump isn't working - possible, but wouldn't resolve the other issues.
 

Kewen300

Cadet
Joined
Aug 9, 2020
Messages
23
First thing to do is pull the flame arrestor off and hold the choke plate open, have someone pump the throttle while you look and see if you get squirts of fuel from the throttle pump. No squirt either means the carb is out of fuel, my guess, or the pump isn't working - possible, but wouldn't resolve the other issues.
Pump is sending fuel as it should. I was thinking vapor lock when the motor quit.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
49,574
Pump is sending fuel as it should. I was thinking vapor lock when the motor quit.
Highly unlikely its vapor lock

Most likely, you need tp service the fuel system
 

jonny rotten

Petty Officer 1st Class
Joined
Jan 8, 2012
Messages
345
Is the cutoff switch working as it should?(stalling)
The slot on the shift lever is to help engage reverse
With the lower shift cable barrel adjusted perfect I still needed to tighten up the upper barrel past spec to engage correctly
 
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