1996 mercury 75 hp carb?

[jackd1023]

Hello and thanks in advance for your help.

I just purchased a used boat from a used car dealer(EBAY). The boat is an 1996 Spectrum 18' with a 1996? 75 hp 2 stroke 3 cyl merc. Only paid $1500 for boat motor and trailer.

They told me that they knew nothing about boats and the gentleman that traded it in said it ran, they however could not get it to start.

I got it home and noticed that the Run/stop switch on the controls were on the off position. I tried to drain the gas tank but it is and internal tank so I am not sure I got it all out. Filled tank with 93octane. I sprayed the crap out of the carbs and pulled and cleaned the plugs. Fired the second crank and ran great.

I then decided to go fishing. Cranked and started spitting water like a champ. I left the launch let it warm up then hammer down. Ran great for about a mile then it fell on its face. I could not get over 3000 RPM and had a nasty loss of torque. Idled great and ran fine till i throttled up. ran a compression test all in the 130 range.

Before I start replacing parts any ideas? I have seen high speed jets mentioned, where and how please. Also the black box (deck of cards) above carbs should I make extinct? My wife is already pissed I bought it (she does not recognize a deal) So if there is a cheap fix would help out my marriage lol. Thanks for the help

 

[Laddies]

Re: 1996 mercury 75 hp carb?

It sounds like a plugged high speed which you can get to by removing the plugs on the port side of the float bowl to clean if you don't want to remove the carbs and clean them which would be the proper repair

 

[jackd1023]

Re: 1996 mercury 75 hp carb?

I plan on pulling carbs this winter was just hoping to get in a few fishing trips before the ice sets in. What about the black box? Thanks a lot

 

[Laddies]

Re: 1996 mercury 75 hp carb?

They never had a idle stabalizer on the 3 cyl 90 that I have seen, it might be a rev limit. what color are the wires and where do they go, plus the serial number would help

 

[jackd1023]

Re: 1996 mercury 75 hp carb?

Thanks for the advice, I cleaned out the high speed jets blew them out and they looked clogged with what looked like 2 stroke oil. I have not water tested yet.

I noticed the black box for lack of a better term, that is on top of the carbs, the wires were burnt. I cleaned soldered and shrink wrapped them it did not seem to make much of a difference thou. Any idea what that is and maybe what would cause them to burn?

 

[jackd1023]

Re: 1996 mercury 75 hp carb?

I wrote down the serial # but have no clue where I put it, I believe that it started with OG could be wrong. I had it looked up at the marina to get spark plugs fuel filter etc.. I was told the engine was a late 96- early 97, if that helps

 

[jackd1023]

Re: 1996 mercury 75 hp carb?

OK the serial # is OG227090

I got the carbs off. I cleaned them there was a lot of black residue in the float bowls. I blew out all the jets cleaned and adjusted the floats.

I did notice when I was taking off the carbs there is a "black box" with a few wires coming off of it. 2 red 2 yellow and a few more . What is this box and what does it do. The wires coming off of them looked to be burned and when I took it off i noticed that the inside looked to be burned too. Some help would be appreciated.

I also replaced the fuel filters new plugs and new fuel line.

I am planning on reinstalling carbs tomorrow but would like to know what that black box is what it does and should I replace. Thanks in advance for your input.

 

[Laddies]

Re: 1996 mercury 75 hp carb?

That sounds like the regulater, heres a parts list for you to check out and that engine does have a rev limiter on it. http://www.ishopmarine.com/ishop/js...cCatFilter=MM&eCatSupFldr=supplier-050-025-MM

 

[Barnacle_Bill]

Re: 1996 mercury 75 hp carb?

Your motor is a 1995 model. That black box is your regulator/rectifier and if the wires are burnt there is a 99% chance it is shot. You should also rebuild the fuel pump while your at it. Be sure to replace the check valves with the new style. They come with the kits from merc.

 

[jackd1023]

Re: 1996 mercury 75 hp carb?

Laddies thanks for response, looks a lot more like the regulator than the switchbox. is there a way to test this or what could cause this to go bad?

 

[jackd1023]

Re: 1996 mercury 75 hp carb?

The book at the local marina said it was a late 96 early 97 model, does not really matter thou, what are the symptoms of a bad regulator?

 

[Laddies]

Re: 1996 mercury 75 hp carb?

Here's the test.

 

[Silvertip]

Re: 1996 mercury 75 hp carb?

There is an easier way to tell what year it is: look at the data plate on the left side of engine. Like this one:

 

[jackd1023]

Re: 1996 mercury 75 hp carb?

Thanks for all of your help, I will let you know the verdict.

 

[jackd1023]

Re: 1996 mercury 75 hp carb?

Thanks again I did order the rectifier should take less than a week I hope. What are the symptoms of a bad rectifier? could this cause the initial problem of not getting over 2k RPM?

I did test it and it was/is bad Just would like to have an idea ifI have to put more money into this thing. Thanks again!!

 

[jackd1023]

Re: 1996 mercury 75 hp carb?

Back again, cold weather is killing me. New regulator/rectifier, rebuilt carbs with gaskets, new inline filter and water separator, new fuel line and bulb, rebuilt fuel pump. New plugs too.

We did a cold compression test while changing plugs, 120 all 3. Good spark with tester, Pumped bulb and it fired right up. Seemed to idle a little smoother hard to tell on muffs. I did notice that my RPM gauge was working (before it was intermittent)

If I get some open water I will be testing as soon as I can. Any suggestions on anything else I should do or check?

 

[jackd1023]

Re: 1996 mercury 75 hp carb?

THANKS EVERYONE FOR HELPING!!!!!

Decided enough cabin fever and took her out on the river today.

PERFECT!!!!!!!

started idled, ran 5200 rmp without missing a beat, bump key and she fires!!

Hopefully I can be of some assistance and have been acused (by the wife) of being addicted to the site lol

 

[gandk]

Re: 1996 mercury 75 hp carb?

hi there i think i have a similar problem, mines not starting after winter and ran fine before no problems. How long did it take to rebuild carbs and fuel pump etc?

 

[fbinsley]

Re: 1996 mercury 75 hp carb?

I dont know how long it will take to rebuild the carbs but I did buy a fuel pump kit for my 1992 75hp and put in on in less than 30min. I have no mechanical skills whatsoever...I am trying to figure out why mine isnt firing.