Classic 50 dies at low idle

[BlueBombNut]

Hi All;

I will attempt to provide all necessary info on my first try I have a mid 80's Mariner 45 hp 4 stroke on my pontoon, I bought it used at the end of last season. It ran great except it was a little hard to start when cold but I think that was due to air getting in the line, I switched the gas line and now it starts right up when choked and the throttle is advanced. It will continue to run if the throttle is advanced but as soon as I bring it back to normal to shift in gear it dies out. The carbs are clean, the plugs were cleaned and do not seem to be fouled (only ran for 15 - 30 min) with muffs. New gas with stabil in it ( I was told to run the gas with stable in it from the guy I bought it from as Sea Foam is too strong to run all the time) any way that could be a whole topic in itself but I just wanted to provide the info.

It is oil injected but the guy I bought from said he disabled the oil injection and said to just mix oil and gas. He gave me an explanation too long to add but it sounded like he really knew what he was talking about.

My thought is that there is a low idle screw that I could adjust, I'm guessing a 1/4 -1/2 turn would do the trick but I didn't want to mess with any of the screws until I asked the knowledge tank. The Throttle arm does advance and on the throttle arm in the motor there is 3 - 4 stop screws one looks like it is for fast idle or WOT, not sure what the middle one is for. The bottom one looks like the low idle stop.

I think that when I bring the Throttle level at the console to the shift area it is cutting out or moving the throttle arm in the motor too far forward, so if I increased the stop to prevent the throttle arm in the motor from closing to far that would allow the rpm's to stay high enough to continue to idle when I bring the throttle control at the console to the shift position.

I know I am really close to getting the blue bomb back in the water so any advice would be greatly appreciated.

History of the Blue Bomb - Make = Kayot Year = 1972 New Floor 2007, New Used Mariner 45 4 stroke - 2009

 

[verado7]

Re: Classic 50 dies at low idle

idle when running on muffs at neutral should be 1000 - 1050 rpm to be correct on the water in gear . there are other things that could cause low idle but check this first .

you can also check the trigger output on the switchbox with a regular voltmeter engine running on muffs in neutral - anything less than 5 volts on these wires would be a bad trigger . black , white , violet , brown . ( sometimes the black wire has a white stripe on it ) they are all the left side of the switchbox -

primary pickup advance can be checked with a timing light - this can cause low idle or stalling if below 5deg.

idle mixture screws set too lean . do the plugs look really dry ?

you may have meant to say this in your post but your motor is a 4cylinder 2 stroke - ( not a 4 stroke ) if she's in good shape -your in luck these are great motors . i currently own an 88 classic fifty