1988 (?) Mariner 150 magnum please help! exaughst flooding issue

Rickeyo

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Mar 11, 2019
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Just bought a 1987 skeeter starfire 180 bass boat, its having a similar problem that an 1988 champion i had did. The champ had a 150 black max xr2, this skeeter has a mariner magnum NOT A MAG II. Everyone says the Mag II is same as an xr2 mercury but idk about the Mag 1. Anyway it looks basically the same but the problem i never resolved on the champ and now have on this skeeter is poor hole shots. It loads up and chokes up when u try to get out of the hole, i trim all the way down for faster stern lift therfore putting the boat on plane as fast as posisble. However it will not take off unless i trim the motor up a little higher because the exaughst relief ports are under water the motor sets so low on the transom. I can then take off working the trim and she gets up and screams! Runs great and idles perfect starts easy etc. Is there anyway to perhaps attach a snorkle of some sort to each of the exaughst ports to get them above the water line to prevent having to take off with the bow pointing at the sky? Its on the lowest setting on the transom mount, but i do not have time to lift it a hole or 2, trimmed level when sitting on the trailer the prop is well below the bottom of the boat, and thing sets so low in the water. I just wish it would holeshot with it trimmed under like my 89 procraft with black max 150 would. Its exaughst ports set about 3 inches above the water at idle where this mariner 150 and my xr2 on my champ set right at water line or even slightly under while idling. Please help!
 

Dukedog

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Oct 6, 2009
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yes, Mag is same as XR2.. most likely ya have carb problems, maybe some bleed problems also.. good disassembly/cleaning, all new gaskets (inside and out) first step.. cheap and easy... check comp, timing, spark, lync n sync... you should never have to do any mods ta make tha motor do right ona bass boat.. some may be under powered but should not stumble and/or load up.... jmo.

all merc V6 carb motors seem ta like level and/or a little positive at idle or very low rpm....
 

Rickeyo

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Mar 11, 2019
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Im putting new fuel filters (it has 1 pre primer bulb and one on motor, is this possibly too much restriction? Normally they only have 1 i thought?) And new plugs plus i will clean the carbs and rebuild them once i get back from this fishing trip. So whats the difference in a Mariner Magnum and a Mariner Magnum II?
 

Dukedog

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Oct 6, 2009
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Mag is 2.0 150 (XR2).. Mag II is 2.4 150 (XR4).. Mag III 2.5 150 (XR6).. Super Mag is Promax.....
 

Rickeyo

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Mar 11, 2019
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So the Mag and the XR2 whats the difference in them vs a straight 150 Black Max? Are the carbs a little bigger and do they run higher rpms or somthing?
 

Rickeyo

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Mar 11, 2019
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Also the motor is mounted on the very last hole on the transom lowest mounting position, i think if i raise it 1 hole it may help me a lot, that may be the first thing i do before rebuilding carbs. Lowest Compression was 121, highest was 129. Motor starts easy, idles perfect, runs great on bottom and top, its just the mid range when im trimmed all the way under where i have issues. I want to be able to hole shot trimmed under so i can get on top quickly, then trim out to WOT. I was just mentioning the snorkle as a temp. Fix for this 3 day outing this weekend. Then possibly try to raise the motor one hole and see if that helps as well as go ahead and rebuild the carbs. Where do i get the right carb kit for thid thing? I have serial number but idk if its an 87 or 88 Mariner Magnum 150, and i know there is a few diff. Carbs they put on these motors isnt there?
 

Rickeyo

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Mar 11, 2019
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Dukedog, tuner? This is a Carbed 87 or 88 outboard. Pretty sure there isnt tuners for these motors like there is for my 2012 EFI optimax. Never seen a Carbed motor of any kind you could "tune" other than just converting to elctronic ignition, better coil packs, etc.
 

Dukedog

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Oct 6, 2009
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exhaust deflector (tuner) bolts to bottom of exhaust adapter in tha down housing.. they came in different configurations.. length mostly.. longer tha "tuner" more bottom end grunt, fewer rpm.. that's tha theory.. something all merc V6's have.. they usually don't do much in tha stock "production" motors but with tha factory "hot rods" and shop built "stem winder" motors with other modifications they can/will have noticeable gains....
 
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