mercury 150 idle problem

[jr85]

i have a 87 blackmax xr2 150 it will idle fine but after trolling out of the no wake zone or picking up my fallin skier when i give it gas to take off it starts to go then bogs and i have to raise the motor to the point the exhaust is out of the water get a few rpms up then lower again which is a real pain in the butt!!! if i put new plugs in it will do fine for a couple trolling periods then back to the same. runs great at wot. any ideas on what the problem could b? thanks in advance

 

[James R]

Re: mercury 150 idle problem

Sounds like it's time to do some serious checking and servicing. Compression test is first. If good check the sparks. Then on to carb cleaning and rebuilding. As it is acting up you will only do damage by trying to run it.

 

[jr85]

Re: mercury 150 idle problem

hi james jus to inform it is a fresh rebuild 110 compression on all and i have cleaned the carbs but not rebuilt im thinking the maybe during the rebuild process i may have got the timing advance that hooked to the throttle linkage out of adjustment. could this b a possible cause to my problem?

 

[Chris1956]

Re: mercury 150 idle problem

If the carbs are clean, and that is a guess since I do not know what you did to them, the carbs could be out of adjustment. of course it is always wise to make sure idle pickup timing and max timing are correct.

 

[jr85]

Re: mercury 150 idle problem

hi chris i took the carbs apart soaked them in cleaner and blew them out with air nozzle but im really thinking it the timing adjustment i didnt move anything when i took it apart but it may need some fine tuning i had one person tell me that because im having to the exhaust out of the water that the upper exhaust ports under the pee hole maybe clogged but that means removing the motor to check

 

[James R]

Re: mercury 150 idle problem

Most annoying. If you don't tell us what has gone before it is next to impossible to provide good assistance. Link and Sinc and check timing. Did you replace the plugs?

 

[aussieflash]

Re: mercury 150 idle problem

Engine rebuilt by mechanic?I would definitely check timing and adjust to spec....11deg atdc pickup/22deg btdc max at cranking.
It does sound like your choking on fuel.First check if you have anti siphon valve.If yes chuck in trash and see if that fixes it.
Pull carbs again and replace all gaskets $8 per set,and all needle and seat $10 a set.Then adjust float height to exact spec 1/16" (1.6mm).
Let us know how ya go.

 

[jr85]

Re: mercury 150 idle problem

hi aussieflash a boat shop rebuilt the motor first boring it 20 over and all new parts, carbs rebuilt, fuel pump, etc then 2 months later it broke a ring and was parked for 2 years. I bought the boat took the motor apart myself had a buddy bore the bad cylinder 60 over and replaced the one bad piston. I had ngk bu8h plugs in it and i was told the correct ones for my motor was ngk buhw they SUCK. I got new bu8h plugs took it out today it did a lil better then i advanced the timing a touch with the screw on the side hooked to the throttle linkage that seemed to help some. So i need to find someone to do a link and sinc for me and im wondering if maybe i need to go ahead a rebuild the fuel pump again it runs great a wot but maybe not getting enough fuel when it under the load of taking off? thanks for all the ideas

 

[James R]

Re: mercury 150 idle problem

Not difficult to do a link and sync. Get a decent manual, even a Seloc, and follow the instructions.