85 hp Merc won't open up

[dreamboat]

I have rebuilt the fuel pump and rebuilt the carbs and installed a glass in-line fuel filter so I can see my fuel is clean. I have replaced the bulb with a good and then a better squeeze primer bulb.<br /> Now.<br />I used to get a stall at 1900 rpm. ( this prompted the rebuilds) now I get a stall between 3 and 4 thousand rpm. Once in a while it will open up and run 5200rpm WFO and act like it should.<br />It idles nice and doesn't foul the NGK's I put in it.<br />I have noticed some of the wiring insulation is old & cracked in the right side of the engine under a 8x8 plastic shield over the stators(?)<br />Am I losing fire and thats the cause of the stall?<br />Q: Is my problem electrical?<br />Q: Should I invest in a new wiring harness ? <br />Q: who is the best supplier for Merc harnesses?<br /> I can't ski behind this because the engine will not runup through the powerband and keep consistant acceleration going right up to 5200 rpm or until you back it off after a skier is up.<br />Thank you all in advance

 

[Chris1956]

Re: 85 hp Merc won't open up

Nightfish, Since you did not post a serial number or year for the motor, it is difficult to assist you. The ignition systems for some motors are stator-switchbox based others are battery-distributor based. <br /><br />If the harness has damaged insulation you really need to fix or replace it. It could cause a major short and subsequent fire. Replacement wiring harnesses are available at www.surplusunlimited.com for many merc models.

 

[booka]

Re: 85 hp Merc won't open up

Nightfish Did you pull the carbs right down? I found on my "78 850 I had the mixture screw too lean. It ran great at idle but wouldn't rev past 2000. Now for the fun part unless you have access to a test tank you need to find a dam/lake or still water to fix.Remove the wraparound and air box. Start the engine and bring it up to the point where it starts to playup. Now adjust the mixture screw on one carb until the revs start to pick up then adjust the other screw. You may need to fiddle for a while but it's great when it comes on song! Good luck and cheers from Downunder

 

[Chucky P]

Re: 85 hp Merc won't open up

My name is chuck . I Have a 76 850. My wires were the same way The stater are most of the wires that rotted. Its not hard to change . Keep asking for places to buy this and shop for it!!! I payed $130 for mine. But I got it the first place I found It . The other rotten wires will be your bottom harnes that is your Plug on side of motor FIX OR REPLACE THE BAD PARTS Before you end up damaging something else ! Good luck Chucky cepy@knology.net