Bringing TBI and Multi Port Fuel Injection to a New Level.     EFI Conversions and Tuning! Seattle to Portland! E-mail Tuning Consultant!
Results 1 to 4 of 4

Thread: Another marine TBI conversion

  1. #1

    Another marine TBI conversion

    I have a 1985 Mercruiser 3.0 4 cylinder in a 19 foot Wellcraft. As I understand it this engine is based of the early 60's Chevrolet that was offered in the Chevy II. I have gathered up the parts that I think will be necessary for the swap. I have the TBI unit off a 3.1 Lumina van, the wiring harness was pirated from a mid 80's S-10 with a 2.5 and a manual tras. The ECM is a 1227747. I've fabricated the adapter to replace the Rochester carb with the TBI. I have the Howell manifold adapter to put an O2 sensor in the "wet" exhaust manifold riser. I bought a Moates tuner, cables and such. So I'm now ready to install it and need some help with or ideas about the "tune". As I understand it, I need to change some things in the ECM or prom, In no particular order. Slow the idle down to allow easier shifting from neutral to forward or reverse. Hook up the shift interrupt switch to "kill" the spark and therefore the torque to the outdrive. (again to make it shift from forward or reverse to neutral). Also need to change the temperature that the ECM goes into "closed" loop as a boat getting fresh water for cooling will probably never see over 180 degrees. (It does have a 165 thermostat). The mechanical aspects of this project I can pretty easily handle, but the computer programming seems a bit overwhelming. I tried to search in another site that deals with boats only and was chastised for putting a "non" marine set-up on a boat. Now here is how I see it, the biggest concern is the explosions that have occurred in boats in the past. I feel the TBI will actually be safer as gas fumes will surely be less with out a vented to the atmosphere float bowl. Any and all constructive ideas will be greatly appreciated.

  2. #2
    Fuel Injected!
    Join Date
    Feb 2013
    Location
    Euless, TX
    Posts
    1,580
    Quote Originally Posted by Lostonthewatertbi View Post
    I have a 1985 Mercruiser 3.0 4 cylinder in a 19 foot Wellcraft. As I understand it this engine is based of the early 60's Chevrolet that was offered in the Chevy II. I have gathered up the parts that I think will be necessary for the swap. I have the TBI unit off a 3.1 Lumina van, the wiring harness was pirated from a mid 80's S-10 with a 2.5 and a manual tras. The ECM is a 1227747. I've fabricated the adapter to replace the Rochester carb with the TBI. I have the Howell manifold adapter to put an O2 sensor in the "wet" exhaust manifold riser. I bought a Moates tuner, cables and such. So I'm now ready to install it and need some help with or ideas about the "tune". As I understand it, I need to change some things in the ECM or prom, In no particular order. Slow the idle down to allow easier shifting from neutral to forward or reverse. Hook up the shift interrupt switch to "kill" the spark and therefore the torque to the outdrive. (again to make it shift from forward or reverse to neutral). Also need to change the temperature that the ECM goes into "closed" loop as a boat getting fresh water for cooling will probably never see over 180 degrees. (It does have a 165 thermostat). The mechanical aspects of this project I can pretty easily handle, but the computer programming seems a bit overwhelming. I tried to search in another site that deals with boats only and was chastised for putting a "non" marine set-up on a boat. Now here is how I see it, the biggest concern is the explosions that have occurred in boats in the past. I feel the TBI will actually be safer as gas fumes will surely be less with out a vented to the atmosphere float bowl. Any and all constructive ideas will be greatly appreciated.
    Plenty of TBI boats were made. Just use the off the shelf mercruiser fuel module with the integrated tank that has an electric pump fed by the stock mechanical pump and you should have no issues. The TBI distributors are retrofit items for carbureted 3.0L engines. As for your closed loop....Most GM engines are programmed to enter closed loop as early as 100F. Put the interupt switch between the module and coil and you should be just fine. Also the TBI marine regulators were sealed and had a small pipe to direct fuel back to the top of the throttle plate should the regulator leak and should probably be sourced and used.
    Last edited by Fast355; 09-16-2017 at 08:37 PM.

  3. #3
    Forgot to mention that I do have the Mercruiser HEI distributor to install as well. Also trying to do this on the "cheap".

  4. #4
    Will the 1227747 ECM work with a 4 cylinder? Will I have to change something to make it work with the 4 cylinder?

Similar Threads

  1. Marine intake
    By Coco524 in forum GM EFI Systems
    Replies: 2
    Last Post: 08-09-2016, 05:51 PM
  2. Marine Intake is on and running.
    By Fast355 in forum OBDII Tuning
    Replies: 52
    Last Post: 04-03-2015, 01:33 PM
  3. Vortec Marine manifold
    By roughneck427 in forum GM EFI Systems
    Replies: 8
    Last Post: 11-26-2014, 05:36 AM
  4. Newbie working on marine TBI conversion
    By sammy2009 in forum Introductions
    Replies: 4
    Last Post: 01-22-2014, 11:05 AM
  5. Help with marine 3.0 mercruiser tbi project
    By 4x4toys in forum GM EFI Systems
    Replies: 20
    Last Post: 07-12-2013, 02:05 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •