Mercruiser 120 No fuel to carb

[Rblosnick]

I need help, going to pull my hair out soon. My uncle gave me a 1984 galaxy, with a mercruiser 120 I/O. The boat is beautiful, he restored it, used it 4 time, then it has been stored for the last 10 years. I changed the plugs,wires, points, condenser, distributed cap. The motor turns over no problem. If i put fuel in the carb, it will run until the gas runs out. Checked and had no fuel to the carb. I then replaced the fuel pump, thinking it went bad in storage. Still no fuel to the carb.

I then looked at the filter at the carb, and it was clean. I blew it out anyways since I was there, and put it back together. I then checked the check ball at the top of the gas tank to see if it dried out and got stuck in storage, didn't seem to be stuck (I stuck it in my mouth and blew,and air came through). I looked at the fuel line to the fuel pump and it seems good, no weak points.

I then got a test tank of gas, hooked up some clear tubing, one end to the fuel pump, and the other end to the test gas tank. No fuel came through the clear tube when I turned the motor over. I then grabbed the tubing out of the test tank and stuck my finger over it and I could feel a small amount of suction, but not much. The boats gas tank has 5 gallons of fresh new fuel in it, so I know that is not the problem. I feel that the pump was put on correctly because I could feel the mechanical arm against the lob and when I pushed it in, I could feel the spring compress as I was tightening the bolts.

I don't know what I could have missed. HELP PLEASE!!!

 

[Rblosnick]

Re: Mercruiser 120 No fuel to carb

Any help would be appreciated. Thanks

 

[Wrongway1]

Re: Mercruiser 120 No fuel to carb

Im having a similar issue. very interested in seeing the remedy!

 

[Rblosnick]

Re: Mercruiser 120 No fuel to carb

I ran a clear tube from the fuel pump to a regular gas can and still no fuel was being sucked up. Unless is did it wrong, I don't think it is the tank. The tank was dry when the boat was stored.

 

[Rblosnick]

Re: Mercruiser 120 No fuel to carb

Does the mercruiser 120 use a lob, or a rod to activate the fuel pump while the motor is turning?

 

[Bondo]

Re: Mercruiser 120 No fuel to carb

Does the mercruiser 120 use a lob, or a rod to activate the fuel pump while the motor is turning?

Ayuh,... I believe it's driven directly off the cam....
I'm also thinkin' it needs replacin'...

 

[Rblosnick]

Re: Mercruiser 120 No fuel to carb

Really! You think it could be the cam. The engine runs perfect when I poor gas in it. I would think if the cam was bad, the engine wouldn't run so good. If it is the cam, is there an electrical fuel pump I can buy?

 

[Eric 3.7LX Alpha 1]

Re: Mercruiser 120 No fuel to carb

Did you try to remove the "outlet" line between the pump and carb, (off the carb end) and stick it into a jar or container, pour gas down the carb and start it as you've been doing? (2-person job).

Needle valve and Seat stuck closed together in the carb-not opening? Not letting fuel into it? it been idle for 10-years.

How about a pressure gauge on the outlet of the pump inline?

 

[Rblosnick]

Re: Mercruiser 120 No fuel to carb

Did you try to remove the "outlet" line between the pump and carb, (off the carb end) and stick it into a jar or container, pour gas down the carb and start it as you've been doing? (2-person job).

Needle valve and Seat stuck closed together in the carb-not opening? Not letting fuel into it? it been idle for 10-years.

How about a pressure gauge on the outlet of the pump inline?

I've done it all, and even disconnected the fuel line before it makes it to the carb and no fuel. i have decided to take it to a shop on thursday to find out what it is. hopefully not an expensive fix. I sure wish there was a electrical fuel pump option, and i would bypass the mechanical pump and be done with this.

Thanks for your comments.

 

[dingdongs]

Re: Mercruiser 120 No fuel to carb

remove fuel pump completely and test it by pumping the arm manually yourself in a fluid and if it works (gushing through)then it must be the cam as not been fitted to the block correctly or a blockage to the carb.

 

[Rblosnick]

Re: Mercruiser 120 No fuel to carb

Well dropped the boat off yesterday morning for my fuel problem. Got it back today running perfect. I am really impressed with how smooth it runs. Looks like the problem was the carb, the float stuck. I also had the impeller changed in the outdrive. I hope the rain doesn't keep me off the lake this weekend, I really want to take it out. It's been 10 hrs since this thing has been in the water. Thanks for the help.

 

[boaterbilly]

Re: Mercruiser 120 No fuel to carb

I had a similar problem with no fuel on my 1968 120. I couldn?t get full throttle and while checking for the source of my problem I checked the fuel filters, both the bowl and the carb. The original problem turned out to be a worn out fuel hose that was twisted. After repairing the hose I had no fuel coming from the fuel tank. When I finally figured out the problem, it was the gasket on the fuel filter bowl had fallen off and the pump was sucking air through the filter. I found the gasket in the bilge, installed it back onto the filter and the fuel pump worked fine.