1975 Mercury 200 20hp starving for gas at WOT

[micoyote1]

I have a 1975 (I believe by the serial #) that starts fine runs fine until I open it up all the way and after about 30 seconds or so it acts live its starving for gas. I can squeeze the primer bulb and it picks back up and runs fine for about another 15 seconds or so the does the same thing. As long as I squeeze the primer bulb every 15 seconds or so I can run WOT as long as I want. I also notice after it does this and when I shut it down it will start fine but when I put it in gear it wants to die out. I have to prime it again and chock it.

I have had the carb rebuilt by a mechanic with 40 years experience, all new gas tank fuel lines, primer bulb and connecters...even replaced the connecter on the engine. Water pump was rebuilt a couple months ago too.

I have read so much on this problem and I am thinking fuel pump but it was just rebuilt and on my engine it doesn't look like it has much of a fuel pump...but I'm kind of a rookie at outboards.

One other question...where along the fuel line should I put my glass fuel filter?

any help would be much appreciated...thanks

 

[flyingscott]

Is the vent open on the tank. You don't mention the fuel pump being rebuilt are you sure it was.

 

[micoyote1]

There is no vent on the gas tank...I believe the vent is on the connection on the gas tank where the fuel line plugs in. The fuel pump is connected to the carb and he put a rebuild kit on both of them.

 

[flyingscott]

Try opening the cap on the gas tank and running it. Most fuel fittings do not provide the vent to the tank. Or have the mechanic who fixed it look at it. When you say the pump is connected to the carb I think it's part of it. But that motor has a separate fuel pump connected only by a fuel line.

 

[micoyote1]

Try opening the cap on the gas tank and running it. Most fuel fittings do not provide the vent to the tank. Or have the mechanic who fixed it look at it. When you say the pump is connected to the carb I think it's part of it. But that motor has a separate fuel pump connected only by a fuel line.

Here is a picture of the fuel pump and the gas tank. Would running it to lean or rich possibly cause this to happen?

 

[micoyote1]

No Title

Will get picture of tank and upload

 

[racerone]

Carburetor has the pump built into it.---An originnal factory tank would have the vent on the cap.----Try running with another tank if you have one of those cheap plastic tanks !----Now the pump is driven by crankcase pulses and there could be issues there.

 

[micoyote1]

I have a new 0lstic tank hooked up to it and there is no vent to open that I can see.Only possible v ed noting would be to open the cap up some. I don't see how the crank case runs the fuel pump...vut I'm not an outboard expert by any means. Could it be running to lean?

 

[racerone]

The fuel pump is driven by crankcase pressure pulses.----------That is the way outboard pumps have worked for many , many years.-------Is the plastic " boost venturi " in place above the nozzle ??

 

[micoyote1]

No Title

Not quite sure what your asking but here is a picture of the tank I have.

 

[flyingscott]

Sorry about that with the fuel pump I get confused sometimes. The new tanks are supposed to vent one way because of the new EPA regs some do it better than others. Try running with the cap cracked

 

[micoyote1]

I will get it back out and run it with the cap cracked open...also going to put hose clamps on all the gas line fittings.if I put in a fuel filter when should it go along the fuel line?

 

[micoyote1]

No Title

Ok I installed a glass filter put hose clamps on every place I could. I installed the filter before the primer bulb and when I primed the motor I could see threw the glass filter that it was drawing some gas from three tank but not a whole lot. It idled for a while with no problem...it took a picture of the filter as the gas was trickling threw it....seemed kinda slow... what do you think? I will get out on the lake and open it up and see what it looks like here in a couple days

 

[MH Hawker]

it still sounds like a vent problem

 

[flyingscott]

Ok I installed a glass filter put hose clamps on every place I could. I installed the filter before the primer bulb and when I primed the motor I could see threw the glass filter that it was drawing some gas from three tank but not a whole lot. It idled for a while with no problem...it took a picture of the filter as the gas was trickling threw it....seemed kinda slow... what do you think? I will get out on the lake and open it up and see what it looks like here in a couple days

That actually looks fine for an idle.

 

[micoyote1]

I'm taking it out on the water tonight and going to try some different things to try and narrow it down...will let ya know.....thanks for all the help so far....

 

[micoyote1]

Here is a video of what it is doing

 

[micoyote1]

Anyone have an idea what is causing this....I am stumped.

 

[flyingscott]

Anyone have an idea what is causing this....I am stumped.

Your video is private

 

[micoyote1]

This one should be public

After I say ...tthat's what she is doing...it gets up to full throtle and I keep squeezing the primer bulb...runs perfect then...till I stop squeezing.i