91 150XR4 Smoking Like Freight Train

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gump

Cadet
Joined
Mar 16, 2003
Messages
8
hey everbody hows it goin? i got a 91 merc 150 xr4 [i think anyway] on a 91 sprint bass boat. i dont really know why its doing it but it is... everytime the motor is running it puts out a massive smoke cloud. it seems to still run pretty good [turns around 58-5900rpm and 48.3mph on gps] it doesnt miss or anything i just dont want this to lead to a bigger problem. i just put new plugs in and new fuel filter. its been doing this at the end of last year and the few times i've went out this year. does anyone got any ideas on whats goin on? i sure do appreciate it.<br /><br />also anyway i can get more speed out of that thing? its a real heavy boat but i'd like to get more than 48mph out of it. thnks
 
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chuckybaby

Seaman Apprentice
Joined
Aug 25, 2002
Messages
49
Re: 91 150XR4 Smoking Like Freight Train

Been there, it's got to be your VRO pump. Some <br />will suggest you remove and run pre-mix. I replaced the pump ..$300 in parts, $100 labour.<br /><br />Either way woth the money to avoid the embarassment.
 
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gump

Cadet
Joined
Mar 16, 2003
Messages
8
Re: 91 150XR4 Smoking Like Freight Train

thanks for your reply chuck... i'm a nub on boat repairs but i'm trying to learn. do you mind explaining what a vro pump is and where it is located. thanks
 
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met128

Seaman Apprentice
Joined
Sep 12, 2001
Messages
31
Re: 91 150XR4 Smoking Like Freight Train

Variable Rate Oiler = V.R.O<br /><br /> If it were my motor I would remove the VRO and premix the oil before you have a lean oil mixture seize the motor..Hope this helps
 
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bret walters

Seaman
Joined
Mar 2, 2003
Messages
73
Re: 91 150XR4 Smoking Like Freight Train

first off, mercury outboards do not have vro. thats what johnson and evinrude have. mercury use a gear drive oil pump as does yamaha and suzuki. <br />now on to your problem, does the smoke ever get lighter, if so at what speed. is the oil pump link rod connected to the oil pump and to the carb.linkage, if it is lose or connected wrong the oil ratio will be 50 to 1 at all times. you need a service manual to correctly adjust.<br />second question. 48 doesn't sound to bad for a heavy boat. how much weight? what size and type of prop?
 
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gump

Cadet
Joined
Mar 16, 2003
Messages
8
Re: 91 150XR4 Smoking Like Freight Train

hey thanks for the replies...<br /><br />yes the smoke does go away and looks "normal" while running but a few seconds after slowing down it begins again. i'm not real sure on the boat weight but i can tell you i have a [from what others have told me] 23 pitch 4 blade small hub prop. it says 2+2 turbo on the prop. wide open it turns 58-5900 rpm and around 15-18 pounds of water pressure. does that help any?
 
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*Daisey*

Recruit
Joined
Nov 1, 2002
Messages
1
Re: 91 150XR4 Smoking Like Freight Train

Hi Gump, know your frustration. We have a 95 Mercury 150 EFI that's doing the same thing. Tried everything even checked the oil injection arm. It wasn't loose and was adjusted to the proper mark. Changed all the filters, plugs and even made sure there wan't any leaks in the fuel/oil delivery system. Had it in last fall for a check at the local Merc dealer and it worked great for approximately one day. Now it's getting worse and worse. Almost embarassed to start the darn thing at the dock. I'll let you know if we find anything.
 
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gump

Cadet
Joined
Mar 16, 2003
Messages
8
Re: 91 150XR4 Smoking Like Freight Train

yea man i know how ya feel. i went and ran mine a couple times again and its still doin it. had the linkage checked and everything was good to go. its not missin or loosin power so i'm just sayin screw it. i'll make a smoke cloud around the dock and live with it. :D
 
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ODDD1

Lieutenant Junior Grade
Joined
Jan 23, 2001
Messages
1,054
Re: 91 150XR4 Smoking Like Freight Train

Gump, a few things that will make this motor over-oil.......in order of likelyhood, a bad oil pump output check valve that is weak and not maintaining a 2 psi head of pressure on the oil pump output.....bleed system check valves that arent working......for Bob, if the prob only shows at initial startup of the day, the air check valve that pressurizes your remote tank may have a plugged bleeder hole, allowing the tank to stay pressurized after the engine is off...this will push oil into the fuel system....
 
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blazed4x4

Seaman Apprentice
Joined
Mar 18, 2003
Messages
47
Re: 91 150XR4 Smoking Like Freight Train

Also, id check and see if the motor is running at operating temp, between 140-160 degrees. Cold motors run rich.
 
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