1986 mercury 45 hp carb problems

I have this classic 50 that when you are trollling at slow speed it will choke down and die, and then you have to choke it once to get it to crank and if you choke it more than once it is hard to crank. it will run pretty good on top end. I have cleaned the carbs and checked fuel pump and it seems fine, the motor set up a couple of year, my question is, if it isnt timed right and carbs in sync with timing exactly can it cause it to die at low speeds. it will idle ok as long as it isnt in gear. can anyone help.

Idling fine while not in gear indicates a fuel restriction.

Did your "cleaning the carbs" involve tearing them down and inspecting/replacing needle valves? if not, that's a good place to start.

When it dies under load it's almost a low speed jet issue.

Other possible causes would be air leaks in the fuel lines, partially clogged filter, small perforation/deterioration of the fuel pump (even if it "seems" fine)

thanks for the response, I did replace the needle valves in carb, I let the carbs soak in carb acid for about 8 hours, sprayed it out with carb cleaner, can it effect the idling in gear if it isnt sycronized right. it sounds kinda muffled when idling in the water, but on land it sounds fine.

At idle the butterfly's are (normally) totally closed, so sync at that point is not overly important.

What would have more of an effect would be a slightly lean condition (idle mixture screw not backed out far enough) or an overly rich condition (backed out too far) which could cause rough idle due to a very minor flood.

Unless you have really messed with the trigger linkage it won't just go out of timing on it's own - so if you simply unhooked the linkage and then put it back when the carbs were reisntalled the timing would be close enough that you wouldn't notice a difference.

The muffled sound (could) be caused by restricted exhaust. It sounds fine on land but once you add water into the mix the exhaust pressure just isn't what it should be and that can cause crappy idle, stalls etc at lower rpms.

It's not overly common but on models such as this that have an exhaust tube (instead just a big exhaust horn like many models), particularly ones run in salt water, can get quite restricted (like build-up in a waterpipe from minerals in the water).

I have seen exhuast tubes so closed down that you could barely get a pencil through the hole that's left.

So first maybe try resetting the screws - all the way in until lightly seated then back out 1 1/4 turns.

And if you feel ambitious maybe pull the lower unit and take a look up the housing with a flashlight and see what kinda shape the exhuast tube is in.

The exhaust tube is about 2'ish inches in diameter and extends part way down into the housing (leg) - the walls of the tube should be "sooty" but there should be no build-up at all on the inner walls.

If there is, it can be cleaned out, but it's a little more involved process - have to pull the powerhead to get at it properly...

I forgot to tell you I did put a new trigger and stator on this motor, but tryed to put linkage back like it was. put new actuator plate on it to. i appreciate your help. I have been working on evinrude motors some I have had several, but not any mercury takes me a while to get the hang of it.

Babington style waste oil heater pumps

The cam gear pump works fine for filtered WVO or used motor oil Babington heaters and I have installed it on my Babington style heaters. Ldu Company's stock number is 450516 , The only thing about the cam gear pump is that the fire kind of pulses as the cam gear rotates. If you use the spur gear pump that is LDU's stock number 450512 then you get a steady non-pulsing fire. The WVO pump website is http://www.liangdianup.com/subpages/oilpump_1.htm or you can click through to the tools section from the home page at www.LDUcompany.com

LDU Company also has other parts that I use for building my waste oil burners, like gear reduction motors. I find it best to turn the pump slower because you really don't need a whole lot of oil dripping on the atomizer ball.

Good place to start is pulling plug wires on at a time carefully with a plastic pliers. That will tell you which cylinders are not hitting. Somthing this old may have worn rings that don't pull vacuum/gas at slow speeds.

I finally just carried to a guy who specializes in mercury motors I will let you know what he found when I get it back.

I had the motor worked on and he cleaned the low side jet and it seems to stay running now, thanks for help