'78 Mercury Black Max 200 HP Won't Start - Help :(

[wooks93]

The previous owners messed with A LOT of the boats tubing / wiring etc.


I can get the engine to start if I spray starting fluid into the air intakes. Then I can start the boat no problem for about 20 minutes, then I need to spray it again.

The gas tank was removed from the front of the boat, and is now replaced by a small, portable 5 gallon gas tank in the back of the boat, that is about a foot below the motor. When I consulted the manual, the fuel line setup seemed wrong. The gas tank (with all the right connecting pieces) goes to a hand pump, then through the fuel water seperator (which I assume has not been checked / or had the filter changed in quite a while) but then to another hand pump, and then to the engine. The first hand pump (closest to the gas tank) never gets firm and always feels like it is putting in about 1/2 air.

I made sure all the connections were air tight, so unless the hose has a tiny tiny hole in it, I don't think it's getting in that way.

All the batteries are in working order by the way, and the cranky thingy does spin haha. It just doesn't fire up.

Sorry for the newbiness. Thanks :redface:

 

[wooks93]

Re: '78 Mercury Black Max 140 HP Won't Start - Help

Re: '78 Mercury Black Max 140 HP Won't Start - Help

Nobody ? I thought i might be able to work on it today

 

[hkeiner]

Re: '78 Mercury Black Max 200 HP Won't Start - Help

I can get the engine to start if I spray starting fluid into the air intakes. Then I can start the boat no problem for about 20 minutes, then I need to spray it again.

First of all, never spray starting fluid into the carbs on a 2-stroke motor. It does not have any lubrication in it, which is bad for the motor. Instead, use a mix of oil/gas (ratio 1:50) for this purpose.

Regarding your problem, it appears to be caused by a fuel supply problem of some sort. As a start, I would suggest doing some basic maintenance stuff first, such as cleaning the carbs, rebuilding the fuel pump, replacing all of the fuel filters, and replacing the squeeze bulb on the fuel line. Use a Mercury OEM squeeze bulb and install only one squeeze bulb on the fuel line. On my boat, the squeeze bulb is located between the fuel/water separator and the motor, about 1 foot before where the hose enters the motor area.

There are also many other possibilities, such as a failed anti-siphon valve, a leaking hose connection, a plugged feed tube inside the tank, etc. I would suggest performing a vacuum gauge test before replacing/repairing all of the other possible causes. Click on the below link for a guide on how to use a vacuum gauge to troubleshoot.

http://forums.iboats.com/showthread.php?t=261581


Another thought...check the link and sync settings to be sure the carb throttle plates are opening and closing properly.

 

[wooks93]

Re: '78 Mercury Black Max 200 HP Won't Start - Help

Okay so I'm just gonna go ahead and replace everything in the fuel line that goes from the gas tank to the fuel pump, and check whether the feed tube in the tank is plugged. I figured I should check the easy things first

Thanks!

Any other responses would be VERY APPRECIATED. Hopefully hkeiner covered it all though haha

Oh also, what kind of oil should I be using? I kindof just picked up the first 2-stroke oil at shucks

And also, but less important, how much is this outboard worth? I didn't realize 200 horses was so big, and i got the boat (complete with engine and trailer) for $1500

 

[hkeiner]

Re: '78 Mercury Black Max 200 HP Won't Start - Help

Another quick troubleshoot method is to connect a portable remote tank to the motor with a new squeeze bulb on the line. Don't use any quick connect fittings. Fasten the hoses directly to the slip-on fittings with tie straps or similar. If the motor runs fine this way, then you have narrowed down the problem area to things upstream of the fuel pump. If it still does not run fine this way, your problem is further downstream. This troubleshooting method may save you some work and frustration by avoiding fixing things that do not need fixing. Just a thought...

 

[wooks93]

Re: '78 Mercury Black Max 200 HP Won't Start - Help

Edit: Oh hahaha nevermind, I see what youre saying. Yeah, I'll try that. Thank you.

 

[wooks93]

Re: '78 Mercury Black Max 200 HP Won't Start - Help

Wait, where is the anti-syphon valve?

Because if it is attached to the actual tank itself... then there could be no anti-syphon valve at all, since it's always running off a small portable.

 

[wooks93]

Re: '78 Mercury Black Max 200 HP Won't Start - Help

Bump.

Where is it?

 

[j_martin]

Re: '78 Mercury Black Max 200 HP Won't Start - Help

Usually it's a check valve built into the fuel pickup in the built in tank. If you blow into the fuel line and you can't blow bubbles in the tank, it has the valve.

They sometimes put too much restriction and back pressure on the fuel system and cause problems.

hope it helps
John

 

[wooks93]

Re: '78 Mercury Black Max 200 HP Won't Start - Help

Bought a new fuel line, and it didn't solve anything.

Sigh...

So the problem is in the actual engine. I'll just have the shop fix it and ghetto-start it for the rest of summer.

 

[achris]

Re: '78 Mercury Black Max 200 HP Won't Start - Help

1. No anti-siphon valves in portable tanks...
2. The fuel lines should run... portable tank to water separating filter to primer bulb to engine... The only quick connect should be at the portable tank...
3. ALL fuel lines to be 3/8" or larger I.D.
4. All lines to be clamped properly, or you'll be sucking air and killing the engine.

Rebuild the fuel pump with new diaphragms....

 

[hkeiner]

Re: '78 Mercury Black Max 200 HP Won't Start - Help

With some systematic troubleshooting methods, you should be able to find or narrow down the problem without spending any "big bucks" on having a shop do it for you. The below linked thread contains a Mercury Service Advisory that describes how to troubleshoot fuel delivery related problems. All you need is a vacuum gauge, clear hose, and a t-connection.

http://forums.iboats.com/showthread.php?t=265390