~1979 Mercury 1150 (distributor-less) Power trim questions

[LennyVidiVici]

Hey everyone, I'm totally new to the boating world coming from the hot-rod world.

A little background:I picked up an older boat for cheap and I'm navigating my way around the engine. It is what I believe to be a 1979 Mercury 1150 with what I believe is referred to as CDI (no distributor). I fixed a wiring issue, and can now start and run it with the key if I play with the throttle. If I go below 1/4 throttle or so with the throttle only button pushed in it dies. My idle control box had a wrecked red wire so I soldered a new one the best I can, but I'm not sure it's working. I am running new premium gas with 50:1 mixture, and I blasted everything with carb cleaner through the fuel line earlier. It seems to run better with the "choke" enrichment solenoid disconnected too.
The questions I have (for now)-
- Can I just adjust the throttle cable so it runs in neutral? I would estimate it running below 1000 RPM judging by the sound when it dies.
- What is the best (in the $20ish range) manual for this type of engine? I can't seem to find the date code on the engine, but can go nuts looking for it if they are that different year to year.
-I'm supposed to have one of these in each carb right? What are they, air bleeds?

 

[Texasmark]

Give a shout to Chris1956. He has a lot of experience with this vintage Merc. in that HP range.

 

[Chris1956]

That jet on the carb bowl you have circled is the "backdraft jet". I do not actually see the brass jet. If it has been removed, the backdraft feature is disabled. You might plug the little rubber tube that runs to the carb throat. If not plugged, the carb could run a bit lean.

As for your slow speed issue, it sounds like you have dirty carbs. Pick up a service manual. An OEM is best. Online manuals can sometimes be found as well.

Clean the carbs, and replace the gaskets, floats and inlet needle and seat. Adjust the float height and drop. Check the idle pickup timing and max spark advance. That should fix you up.....

 

[Texasmark]

That jet on the carb bowl you have circled is the "backdraft jet". I do not actually see the brass jet. If it has been removed, the backdraft feature is disabled. You might plug the little rubber tube that runs to the carb throat. If not plugged, the carb could run a bit lean.

As for your slow speed issue, it sounds like you have dirty carbs. Pick up a service manual. An OEM is best. Online manuals can sometimes be found as well.

Clean the carbs, and replace the gaskets, floats and inlet needle and seat. Adjust the float height and drop. Check the idle pickup timing and max spark advance. That should fix you up.....

Go to the top of the page and open Boat Parts and Accessories. In the question box, insert Seloc Manuals. You can rent time online or buy a hard copy. I rented time when I used them and it is as fast as you can give them your CC#......that's what I did. Liked the service and the manual.

 

[LennyVidiVici]

Thanks for the quick responses guys, I'll pull the carbs and get a serial number to get the right manual.

The lowest of the 3 cars has a backdraft jet (0.085 I think) and the other 2 have empty tapped holes that look like fuel leaked out of when I flooded it. There are rubber lines going to the top of the bowls, so I guess it's not technically disabled. I'll have to get a manual and read about it more I guess.

 

[Chris1956]

Lenny, The backdraft system allows the carb throat to pull air out of the carb bowl. The brass backdraft jet restricts the amount of air that is pulled, causing a vacuum in the carb bowl, and leaning the mixture. If the brass jets have been removed, the backdraft system will not function.

 

[LennyVidiVici]

Lenny, The backdraft system allows the carb throat to pull air out of the carb bowl. The brass backdraft jet restricts the amount of air that is pulled, causing a vacuum in the carb bowl, and leaning the mixture. If the brass jets have been removed, the backdraft system will not function.

Thanks, I guess it does the opposite of what I thought it did.