late 1980's 45 hp mariner will run at high idle but soon as put into gear shuts off

[matthew1982]

I have a late 1980's mariner45hp that just won't run.
I've replaced the spark plugs, Cleaned the carbs, cleaned the fuel pump, checked the fuel filter, checked the fuel pick up tube in the tank,...i went trough the entire fuel system..
Before I did this it was hard to start and now It won't start at all, When I could get it to start it was in a high Idle then soon as I lowered the idle and put it in gear it would shut off. it ran a couple of months ago fairly good, then started runing like crap, and now this. I've done everything I could think of and am still leaning towards a fuel issue. Just need some more advice on what to look for.

 

[CharlieB]

Re: late 1980's 45 hp mariner will run at high idle but soon as put into gear shuts o

Verify a good hot spark of 7/16 inch to rule out any ignition issue.

Verify compression to rule out any possible mechanical issue.

Once both of these check out then you can be pretty sure that you still have a fuel issue.

Double check the carb cleanliness, especially the small idle fuel passages. Initial idle mixture adjustment is 1 and 1/4 turns out from LIGHTLY seated.

Be sure to use carb kits with new gaskets and that float heights are set correctly.

Leave the fuel hose off the carbs a minute and crank the motor, observe for a strong pulsed fuel flow. The pump can be clean but have a leaky valve and not pump adequately.

Install a temporary clear fuel hose between the fuel pump and carbs, start the motor and watch for any air bubbles passing thru which would indicate air sucking into the fuel system anywhere before the fuel pump.

Repost your progress and any findings or problems.

 

[matthew1982]

Re: late 1980's 45 hp mariner will run at high idle but soon as put into gear shuts o

Verify a good hot spark of 7/16 inch to rule out any ignition issue.

Verify compression to rule out any possible mechanical issue.

Once both of these check out then you can be pretty sure that you still have a fuel issue.

Double check the carb cleanliness, especially the small idle fuel passages. Initial idle mixture adjustment is 1 and 1/4 turns out from LIGHTLY seated.

Be sure to use carb kits with new gaskets and that float heights are set correctly.

Leave the fuel hose off the carbs a minute and crank the motor, observe for a strong pulsed fuel flow. The pump can be clean but have a leaky valve and not pump adequately.

Install a temporary clear fuel hose between the fuel pump and carbs, start the motor and watch for any air bubbles passing thru which would indicate air sucking into the fuel system anywhere before the fuel pump.

Repost your progress and any findings or problems.

I did check out spark and compression both are good, the fuel pump has a strong flow, so its back to the carbs again, getting the bottom off is a real pain, one nut is behind the starter any ideas on how to get at it? cant use a socket and the position is where a wrench can't turn it...i dont want toeat it up with pliers...

 

[matthew1982]

Re: late 1980's 45 hp mariner will run at high idle but soon as put into gear shuts o

ok I got the carbs cleaned and put back on I got the boat running againbut now i can't get it to engage the power band, It runs and drives but has no pick up speed and it leaking alot of fuel/oil mix out of the exhaust..back to the drawing board trying to figure out the new problem, but did get it back to running status and able to move it...I think it could be a idle port adjustment on the carbs.. any ideas??