95' 150 Mercury Black Max....TROUBLES

[basshunter21]

New too this forum..anyways boat a 95' Astro with a 150 black max on the back...everything was great for two weeks..UNTIL..I was running in a tournament and all the sudden the yellow buzzer went off don't know what it means...figuring overheat...anyways it went away and ran ok for a while...now it smokes during all stages the quick out of the hole is good sometimes...and sometimes it's slow....also I'll run for a while and the rpm's are only getting up to 4600 and it's not hitting top end speed but about 2-3 minutes it took off and ran like it used to...I have know idea whats going on....HELP

Previous owner rebuilt engine two years ago due to a burnt cylinder cause of oil injection since then he's been mixing 50:1 and leaving the injection out...I'm new to big boy boats and motors and need help...don't know hardly anything about the motor to fix it..and I'm not spendin all my money on this thing...I can fix things my self if I have some pictures and labels of what things are in this engine....HELP ME PLEASE!!!

 

[CharlieB]

Re: 95' 150 Mercury Black Max....TROUBLES

You should not try to throw parts on or spend any money other than to buy a few hand tools and a Factory Service Manual.

Absolute essentials are:

Spark Plug Wrench
Compression tester (screw-in type)
Spark tester
Remote Starter Switch

With these few tools you can determine most any problem with your engine.

Test for a bright blue "Crack" 7/16 inch long on all cyls to be sure that you have a good ignition system.

Test compression to make sure that all cyl's are within 10% (or less) of each other.

If both test are good then you can be sure that the problem is in the fuel system, i.e., weak fuel pump, dirty carbs, dirty filter, etc.

Repost with your findings and we can assist you more.

 

[basshunter21]

Re: 95' 150 Mercury Black Max....TROUBLES

I appreciate the response and I'll Definetely get a manual...anyways I don't think it's the fuel system just because it starts right up no problem....another thing is when it's in idle the rpm will hold at like 800 then occasionally start jump every 5 seconds to a little over a 1000......the thing looks brand spankin new underneath the cover...like i said rebuilt two years ago....i just don't know why it smokes throughout the rpm levels and why it runs at 4800 rpm while on plane and then takes off like it used to do up to 5300...when it does finally hit right it's like things are back to normal....I'd like to take a look at the carbs...any suggestion on what the problem is?