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Gas Problem or Something Else?

Gas Man

New member
I have a 1988 Merc Cruiser 120, 4cyl inboard/outboard engine that has always has gas problems. Lately, I put a rebuilt carb on her and I have to prime it before she starts and once started she runs fine. However, when accelerating she will hessitate, backfire, and sometimes stall but she'll start right back up again. Only have to prime the carb when it's been sitting overnight. Took the carb back to the guy who rebuilt it to check the accelerator pump and he deterimined everything was fine and that it wasn't a carb problem. The fuel pump seems to be working fine also. Any suggestions what to check next?
 
See the yellow hose from the carb to the fuel pump?

It have fuel in it ? If yes the pump went.

What pressure the fuel pump giving you ?

You have water in the fuel ?

If you have a fuel water sep. dump the filter into a clean clear container and let sit water will be on the bottom.

Copied here from another website i post to:

I pumped all the fuel out of my onboard fuel tank when i got it.

You can do one of 2 things, pump the water out of the bottom, or all the fuel out and here is how.

If you just wish to pump just the water out of the bottom of the fuel, you will need to purchase a cheap electric fuel pump from any auto store dc powered.
You will also need about 15 foot of cheap fuel hose from the auto store and clamps to fit the fuel pump.

Install the hose on the fuel pump both ends and cut about five feet on the sucking side of the pump just look for the arrow on the pump.

Remove the fuel pickup tube it's the one where the fuel hose hooks to the tank a 90 degree angel fitting, it's a anti-siphon valve. Unscrew it.

Crank the bow of the boat all the way up, and stick the hose connected to the electric fuel pump 5 feet into the bottom and back of the tank.

Into a clear container pump the water out till you see clean fresh fuel and stop the pump.

Or into a large container pump all the fuel out.

Now check the valve by blowing thru it, check the screen thats its clear.

Install the valve and pickup tube your done.

Question do you have a fuel water separator on the boat, good to have.

Good luck !
 
It sounds like you have a fuel issue. Insufficient fuel getting to the carb. Hose from the tank to the pump may be swollen inside. Pump may be weak.
See the yellow hose from the carb to the fuel pump? It have fuel in it ? If yes the pump went.
I've seen a failed pump that did not have fuel in the yellow hose. The reason was the nipple the hose attaches to was plugged w/a gob of hardened fuel varnish from a slow leak.
 
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