Go Back  Offshoreonly.com > Technical > General Q & A
5.7 Alpha 1 thunderbolt 4, randomly shut off at cruise >

5.7 Alpha 1 thunderbolt 4, randomly shut off at cruise

Notices

5.7 Alpha 1 thunderbolt 4, randomly shut off at cruise

Thread Tools
 
Old 07-24-2020 | 12:35 PM
  #1  
Thread Starter
Registered
 
Joined: Jul 2020
Posts: 1
Likes: 0
Question 5.7 Alpha 1 thunderbolt 4, randomly shut off at cruise

Hey all,

Have a 93 Ciera 2655 with an early alpha 1 gen 2 outdrive and a new (13 hours on it) 5.7. Full closed loop cooling.

Today I was running it at cruise ~3400 RPMs and planed out. Suddenly she lost power and stalled. Reset the shifter to N, cranked it and she fired right up. Got it going right back up to cruise and headed for the dock, worked fine. I had been running at low speed and high speed for about 1.5 - 2 hours prior to the stall - no hiccups nothing... This stall was super random. I have my kill switch/lanyard bypassed so it was not that. Boat has a new (sierra) coil for the Thunderbolt 4 ignition, new edelbrock marine carb as well as the latest trigger assembly in the distributor. New plugs (new freaking engine).

Any ideas?
Biggyniner is offline  
Reply
Old 07-24-2020 | 01:06 PM
  #2  
Registered
15 Year Member
 
Joined: Oct 2007
Posts: 8,439
Likes: 94
From: yorkville,il
Default

the key switch might be the problem,pretty easy&cheep repair.
mike tkach is offline  
Reply
Old 07-24-2020 | 02:30 PM
  #3  
Registered
15 Year Member
 
Joined: Oct 2007
Posts: 69
Likes: 12
Default

Originally Posted by mike tkach
the key switch might be the problem,pretty easy&cheep repair.
I had a 1990 5.7 with an Alpha Drive many years ago. It just quit out of the blue like you described. It took me a while to find it on the water but it was the shift interrupter switch which was located on a plate with the cable adjustment. It has a microswitch that momentarily kills the ignition when you switch from neutral to forward or reverse gear. I forgot if it was an adjustment or the entire microswitch was bad and I had to replace it.
kornegle is offline  
Reply
Old 07-24-2020 | 03:13 PM
  #4  
Registered
15 Year Member
 
Joined: Sep 2008
Posts: 916
Likes: 41
From: Tampa Bay Area Florida/ North Miami Florida
Default

Try this with key in on position and motor not running, at least on mine, the alarm horn is blaring. Soon as it starts up and builds oil pressure the horn stops blaring. So while its on and not running , start pulling fuses at the fuse block.untill the alarm stops. Either sand the metal on the fuses a little or put in new fuse. I have had that exact problem. Its like fuse had some corrosion and would intermittently lose connection. It too was a bayliner not that means anything but just saying. I would also ditch the seira coil and put in a Flamethrower 2 coil or a msd Blaster 3. Both have very similar resistance to original Mercruiser. Last and not least change the coil wire . Remember it fires 8 times for every 1 time a plug wire fires as there are 8 plugs and only 1 coil wire so it will wear quicker.

Chris.
Blueabyss is offline  
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.