Low wot rpm's on my 1987 150hp merc

[angles4lyfe]

Hi i recently bought a new boat its a 18ft 1985 hydra sport with a 1987 v6 150hp merc on it. the boat had been sitting since 1998 and hasnt been turned on since. so i went ahead checked to see if it would turn over and yes the previous owner and sprayed oil in to the piston so it wasnt stuck. i checked the compression 120 on all cylinders. I went ahead and rebuilt the carbs, put in new spark plugs , check if i had spark and I do and put in all the fuel hoses new because they were bad. well yesterday i take the boat out to try it out, it turns on and idles great. i drive it down the channel perfectly with no prob, once i get to the en of the channel i take it all the way down to WOT and it gets on a plane immediately but it wont pass 3500 rpms. it seems to me like if i was only running on 4 pistons because it would ocasionally miss and shake a bit and actually feel like if it had no power. can anybody help me out with this?

 

[Kenny Bush]

Re: Low wot rpm's on my 1987 150hp merc

Get a manual and go through the Ten Commandments. You have a lot to check for. Are you a good marine tech?? Since compression looks OK, put a timing light on each plug wire to check for good spark pulse. Make sure she is firing good then move to Fuel system (you can periodically pull each plug to ensure gas/oil is getting into each chamber. Check timing and linkages. All this will be simplified in the manual.

 

[angles4lyfe]

Re: Low wot rpm's on my 1987 150hp merc

yea i have a manual i was checking the timimg and it seems pretty way off so i guess its that.

 

[LubeDude]

Re: Low wot rpm's on my 1987 150hp merc

Id oubt your timing is off, ot wont move just sitting there unless you messed with it. My bet is that you need a new fuel pump.

 

[angles4lyfe]

Re: Low wot rpm's on my 1987 150hp merc

well i went ahead and did the timing and sync and it was way off now how could i check if the fuelpump is bad?