[Boscusjamal]

Hi, I am new to boating and this site. I became the owner of a 1971 MFG Gypsy with 1971 135 Mercury. The motor starts right away and runs on idle just fine I guess. The problem occurs when I apply a load, the motor stalls out unless I pump the fuel bulb. I am loosing fuel pressure. I changed both fuel pump gaskets . Where should I go next, the Carbs? Or are there bigger problems? Also I changed the plugs and it has fresh new gas.

[Chris1956]

Check the fuel line for air leaks, especially at the tanks and motor.

[j_martin]

Originally Posted by Boscusjamal

Hi, I am new to boating and this site. I became the owner of a 1971 MFG Gypsy with 1971 135 Mercury. The motor starts right away and runs on idle just fine I guess. The problem occurs when I apply a load, the motor stalls out unless I pump the fuel bulb. I am loosing fuel pressure. I changed both fuel pump gaskets . Where should I go next, the Carbs? Or are there bigger problems? Also I changed the plugs and it has fresh new gas.

The usual failure in the fuel pump is the little disk valve thingies. How did they look?

hope it helps
John

[hkeiner]

If the above good suggestions don't solve your problem, you can can consider troubleshooting with a vacuum gauge. With this gauge, you can test for a fuel line restriction between the fuel pump and fuel tank, a weak fuel pump, or an air leak in the fuel line. Any of these three situations can cause the sympoms you describe. The below linked thread has a guide on how to use a vacuum gauge. The symptoms described in the thread may be different than yours, but the troubleshooting tests still apply.

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

[Boscusjamal]

I will look into all those suggestions thanks for your help and interest

[Yepblaze]

I'd initially look towards the fuel pump and lines feeding it for air leaking in.

As far as the fuel pump(s) I would probably kit(repair/rebuild using a kit) those with the check valve kits as they come with the diaphrams too.