1991 Mercury 200Hp Offshore-Starting Difficulty

[Randy W.]

My first Post! This engine has been hard to start for several years, even after a professional carb rebuild 2 yrs. ago ($600+). This past summer a mechanic came down to the dock and helped me start it after the primer bulb would not get hard. He indicated that I might have a stuck anti-siphon valve in the tank. It started after he knocked on the tank a couple of times with the handle of a hammer. Once it starts, it runs great all day. Additionally, when it starts up initially--it smokes excessively. Could this be a tank/anti-siphon valve or fuel line problem, or should I concentrate on the engine. The choke mechanism appears to be working properly--fuel drains out when activated.

 

[deejaycee_2000]

Re: 1991 Mercury 200Hp Offshore-Starting Difficulty

Welcome to Iboats ... .... nice motor I must just say ..... have you tried it with a different normal portable tank with fuel line to see if the problem is the same? ......

 

[andy6374]

Re: 1991 Mercury 200Hp Offshore-Starting Difficulty

The primer bulb never gets hard and just keeps pumping gas?.....

Sounds like your floats are set too high and/or you needle isn't seating properly. Do you see gas dripping from the carbs?

This will definitely cause the motor to start in a cloud of smoke due to all the excess fuel that is getting into the intake mainfold.

I also do deejaycee_2000 recommened, just to rule out any tank problems.

 

[robalofish]

Re: 1991 Mercury 200Hp Offshore-Starting Difficulty

**** IMPORTANT **** Do a search on my name for an old post re: smoking engine and the remote tank pressure valve on the engine --- I'll bet this is your problem.

Please advise status.

.)

 

[robalofish]

Re: 1991 Mercury 200Hp Offshore-Starting Difficulty

**** IMPORTANT **** Do a search on my name for an old post re: smoking engine and the remote tank pressure valve on the engine --- I'll bet this is your problem.

Please advise status.

.)

Found info here it is below.... This was many hours of checking in order to find this was the problem.

»UPDATE ** UPDATE I found what the problem was on my rig now you can check yours

The reserve tank has been holding pressure for weeks at a time. I didn’t think anything of this as it has done this sense I have had the boat. I found that this is NOT normal. The valve that comes from the engine and supplies the pressure to the remote tank is supposed to bleed off the pressure after 5-10 min. When I checked the valve there was no bleed off occurring. Purchased a new valve and it bleed off as described. So after changing the pressure check valve I have cured the problem.

Check Valve number 21-878105 1

Just a note letting you know the outcome.

Thanks

 

[Randy W.]

Re: 1991 Mercury 200Hp Offshore-Starting Difficulty

Thanks for all the great info. Can you point me to where this check valve is located on the engine. Is it close to fuel pump?? I have a Clymer book, but it is not detailed regarding the 1991 200hp. Is there a diagram I can get of this part relative to installation. Thanks again.

 

[robalofish]

Re: 1991 Mercury 200Hp Offshore-Starting Difficulty

the easiest way to find is to follow the oil hoses that come from the tank. One will go to the oil tank on the engine, the other one will go to the valve in question.

Good Luck

RFish >()>.).)