86 150 mariner idle problem

[cspen]

I have a 150hp mariner magnum ser#A943153 that doesn't idle or start well.Top end was rebuilt by Merc dealer has good compression.Carb were disassembled and all passages blown thru,then rebuilt at a later date by a boat mech.The engine spits back some at a idle like its running lean.Stator was also replaced due to overheated wire.Runs good above an idle.any advice greatly appreciated.<br /> Thanks Chris

 

[Kiekhaeferscurse]

Re: 86 150 mariner idle problem

Hi cspen<br />You might of hit the nail on the head, check your Sparkys they will give you a hint as to how your engine is burning (lean, rich Just right) consult a plug chart (im most manuals) Dont forget your really dealing with 6 little engines and each side of the 3 carbs must be adjusted accordingly. You might want to have a shop with a metered tach thathas an adjustable scale set those carbs for you. Doing it by ear or with the boat tach is near impossible with that big V6<br />When its set up right it should turn key start with no throttle advance (when warm) & should neither bog or spit when you gun it underload.<br />Let us know what story the Sparkys are telling you. Cheers for now.

 

[cspen]

Re: 86 150 mariner idle problem

Thanks Kiekheaferscurse but theres no adjustment screws on the carbs for idle miture that I can find?Will check the sparkys to see which cyl is causing the problem though.

 

[cspen]

Re: 86 150 mariner idle problem

I had another thought about my problem after looking at the parts break down.All three carbs are different.Is it possible that they maybe mounted in the wrong place and if so what is the difference and how doI tell which goes where

 

[cspen]

Re: 86 150 mariner idle problem

still looking for info on the mariner thanks chris

 

[Kiekhaeferscurse]

Re: 86 150 mariner idle problem

Hi Chris. Me bad I didnt read your serial # and jumped to the conclusion of carb adjustment, your carbs are non metered using a fix air jet to set the idle mixture.<br />how did those Sparkys look are they all burning the same? Nice tan colouring?

 

[cspen]

Re: 86 150 mariner idle problem

Hi Kiekhaeferscurse,well the sparkys aren't tan they are oily.I have finally received my manual and done a few things since last message.I pulled the carbs and checked the reeds,they looked fine.I checked the carbs again for the third time once again they look fine all ports clear.I checked all the recirculation tubes all secure.Found one check valve that had oil in it may have been a little clogged.I wish that I would have removed the reeds completly may do that next,also going over the timing soon as possible.Manual says change jets and run hotter plug?

 

[Kiekhaeferscurse]

Re: 86 150 mariner idle problem

Hey Chris, sounds like your getting to no that engine real good. Good to see you purchased a manual.<br />Does that engine idle okay when it has warmed up?<br />Can you confirm that the Sync & link were performed to factory spec's when they rebuilt your motor (ie Idle timing butterflys on carbs closed at an idle, pickup timing set?)<br />Also what was the idle speed in gear in the water when warm?<br />I dont have access to service bulletins anymore, but I do seem to remeber(I'm getting old and memory is failing) that there was a lot of bullitins on the carbs on those engines.<br />Hold off on the jetting and plug changes for now. One other thing did they install new thermostats & Pressure relief valve when they rebuilt your motor?<br />Is North Carolina at Seal level?<br />Hang in there your gonna get this motor purring yet.

 

[Kiekhaeferscurse]

Re: 86 150 mariner idle problem

God my typing sucks just read my post. hope you can make sence of it.

 

[cspen]

Re: 86 150 mariner idle problem

I have read the manual and thats my next move[timing and carb settings]They didn't tell me if they did put in a new thermostat.Should I go ahead and do that?I'm concerned that I have a pressure problem in the crankcase I saw a little oil[and a puff of smoke] around the sensor on the oil pump while running it on the water hose.But the timing and carb settings will come first.I have put up with this problem for several years and nothing has gotten better or worse.The boat runs great above an idle and does idle a little better after its warm but not good enough to manuver around docks comfortably.Will keep you posted I have to much money invested now and have decided that all of the local shops[what few there are]don't want to help me they just want more money.So please have patience I will keep you posted and be picking your brain<br />Thanks Chris

 

[cspen]

Re: 86 150 mariner idle problem

Oh yea we are 900' above sea level

 

[cspen]

Re: 86 150 mariner idle problem

Kiekhaeferscurse,I was reading in the manual and I found out something very intresting.The diaphram on the fuel pump can let gas into the crankcase if it has a pin hole in it and will only effect the idling and will cause hard starting along with plug fouling.I'm intending on replacing the diaphram just for kicks.I don't know if its ever been replaced,I know it hasn't since I've owned it.I don't think the cost will be bad and it will give me peace of mind.I will keep you posted on my results<br /> Thanks Chris