Carburetor rebuild Help

[al9981]

I rebuild my carburetors on my 1987 75hp Mariner 4 cylinder 2 stroke couple days ago. It wasn't easy, but after I got the floats adjusted and the carbs quit leaking gas from the floats being upside down. I found out that the bulb isn't getting hard enough as before the rebuild. I mean, i can keep priming it a little after the carbs are full, but there is no gas leaking in the motor, but I can hear the air bubbles inside the gas tank. It wasn't like this before the rebuild so what did I do wrong. And I switched gas tanks and it still the same even with a full tank...
After the rebuild, the boat starts right up, put in water and runs like brand new. Idles fine, and the pick up is great.
I am wondering if I am squeezing the bulb too much to push the gas back into the tank. But I thought the bulb is one way flow.And the bulb and the gas line assembly is only couple months old. So I am a little confused. Any help is appreciated it. Thank You.

 

[al9981]

Re: Carburetor rebuild Help

Alright, since I didnt get any help, so here is some updates.
I took the boat out three times this past weekend. The first couple times, I cruised around, fished but no tubing. It ran fine on all RPMs. On Sunday, I took the boat out and it was fine till somebody needed a tow to the dock. I towed him on slow speed and it was all fine. I shut the motor to get the ropes out of the water and they pushed me back in and I started the motor and now it didn't want to go over 3000 RPM again and it want to stall and die. But when I floor it, it takes off and go. so I believe my initial problem still there and the rebuild didnt help it. Here s what I thought and what I did.

I remember that I put the floats upside down. I didnt measure the float to the bottom of the carb, which in the manual it said it must be 11/16". So I got that fixed. I changed the springs on the enrichment valve. I tried to get the jet (vent bowl 0.92) out of the top carb, but I couldn't. The top of the screw started to strip bcz it is brass so I left it alone. I was able to replace it on the bottom carb. The new Jet (Vent bowl 0.92) is closed in the center, but the old one is open. I am not sure why is that, but I am guess so the carbs wouldn't leak the gas when the motor is tilted all they way up. I also replaced the little screw on the enrichment valve. On the bottom carb, that valve was alittle loose. I checked all spark plugs and they all look the same. so I know they are all working.

I know I didn't get any help as I expected, but I hope others will learn as I learn on my own. I don't have much knowledge with outboards and I am not sure what else to check for if my problem isn't solved.
Again, I thank everybody for their help!

 

[red cobia 17']

Re: Carburetor rebuild Help

I just rebuilt my carb's also and it didn't help.but my problem is similar to yours but a little worse.I haven't gotten around to checking my carb's yet but I'm getting ready to.Maybe this weekend.I'll let you know.

 

[red cobia 17']

Re: Carburetor rebuild Help

Well I got a chance to check out my motor and found gasket leaking water at bottom of power head.EVERY THINGS ON HOLD NOW.

 

[henrye718]

Re: Carburetor rebuild Help

Borrow a ball and tank to make sure nothing is clogging or screwed up there.

It sounds like something is clogging then freeing up over and over.

When you rebuilt the carbs did you find and put back that lil clip that holds the needle valve to the floats, its so the weight of the float pulls the needle down when the bowls empty.

Next time that happens try and shut down cylinders by pulling out plug wires to at least find out which cylinders are not working at the moment, thats what I think is happening. obviously the ones that are still running when disconnected will shut the engine down to the point it wont even start.

Its possible something is getting hot and causing the malfunction, a wiring harness with a slight break in it could cause disconnection inside the wires due to thermal expansion. etc etc.

I think I would start by looking at the whole fuel system end to end, clean out every line, open the fuel pump, look for and clean any debris in everything. Also look for possible places where air could leak in from in from the fuel lines.

 

[al9981]

Re: Carburetor rebuild Help

well, I have two tanks and it is the same with both tanks. But I notice that I can hear bubbles inside the tank more when the tanks are half way. It makes me want to buy a new gas tank.
For the carburetors, everything is done to them correctly and done by the manual specs. The motor starts like a brand new motor and idles and takes off like a rocket. But it acts up some times after 3000rpm and i did not start to notice it till i started pulling tubes.
I rebuild the fuel pump and I found out that there is no fuel filter on this motor except the the screen inside the fuel pump.
Should I add a filter before or after the pump?

 

[henrye718]

Re: Carburetor rebuild Help

I have seen it before, after and none just like your motor. I dont know but, every car I worked on always had the filter before, so that is where I would put it. especially if you have metal gas cans.