850 merc jumped the red and white post power pack

[roger3645]

I’m running a 1975, 850, 85 hp mercury. I previously posted that I’m having a problem with the motor cutting off at WOT. Also there was a humming or clicking noise coming from the area of the key switch in the control box. It was suggested that I use a jumper wire to connect the red post to the white on the power pack. So here’s what I did.<br /><br /> First I ran sea foam thru using the directions posted. Got quite a bit of smoke the #2 spark plug came out all sparkly and new looking while the other 3 were a bit cleaner but nothing like the number 2 plug. After shutting off the motor I did notice fuel dripping from the bottom carb.<br /><br />I connected a spare control box to the motor and fired it up no more clicking noise from the area of the key switch but the choke button didn’t work. But amazingly enough, the tach now works. Hoping this was the problem to end my woes I tried to run her up to 5000 rpms (test tank prop off) Anything past 3K and it’ll shut down. So then I used the jumper wire red to white, same thing, anything over 3K rpm and she’ll shut off. Is it the float in the carb flooding out the motor? Or could it be something else. Will do a compression check next weekend.

 

[Clams Canino]

Re: 850 merc jumped the red and white post power pack

Originally posted by roger3645:<br /> I tried to run her up to 5000 rpms (test tank prop off) Anything past 3K and it’ll shut down.

Fist of all, never EVER exceed 2000 RPM with an inline in neutral or propless. They are meant to rev only under load.<br /><br />Past that, I'd suggest cleaning the carbs and doing a link and synch as per my post. Doubtfull the switchbox would be the villian.<br /><br />-W

 

[roger3645]

Re: 850 merc jumped the red and white post power pack

Okay! I'll never run that high in a test tank again. Switch box? Just got finished checking the part #. I have the wrong switch box on the motor. The part number matches the switch box for a in line 6 and not an in line 4 cylinder. Could this mis matched switch box be causing the problem?

 

[Laddies]

Re: 850 merc jumped the red and white post power pack

The only differance in the 2 switch boxs on a 4 or 6 cyl. is the tach sencer lead and it's not uncommom to seem a 4 cyl box on a 6 or vice versa

 

[roger3645]

Re: 850 merc jumped the red and white post power pack

Okay thanks! but will the tach read correctly?

 

[Laddies]

Re: 850 merc jumped the red and white post power pack

No it will read the RPM for a 6 cyl. disconnect your tach wire and test run the engine the problem you are having could be a bad tach, thats why the took them out of the ign. system and hooked them to the alt. on all the newer engines