Boat will only run for a minute 4.3 Mercuiser

[rgibbs9651]

I have a 1997 4.3 and was having intermitting stalls on the boat. It would start and run for less than a minute at idle, shorter with the throttle open. I check the fuel for water, changed the filter and check the carb. Everything seemed fine. I got a hose and ran it from a gas can to the filter intake. Still had the same problem. Because I used a clear hose on the last test I could see the fuel pump start and then it was cutting off. I started to search for the price on a new fuel pump and run into pricing for a fuel pressure switch. I notice my fuel pressure switch had oil on it. I jumped the wires together and the engine run fine in my driveway for at least 5 minutes. I disconnect the the jumper and soon the engine died. I am going to order a fuel pressure switch for $25 instead of a fuel pump for $200. The only question I have is if I just jumper the Fuel switch out is there going to be a problem. The oil pressure gauge seems to work and is setting at 40 when the engine is running.

I know the fuel pump is tied to the on position of the key switch. But my boat has an audible alarm to let you know the key is on but the boat is not running. So as long as the key is off the fuel pump should be off.

 

[Don S]

Re: Boat will only run for a minute 4.3 Mercuiser

You don't exactly understand how the fuel pump works on your boat.
When starting the engine, power to the fuel pump is from the starter solenoid. Once started power comes through an oil pressure switch ( what you are calling a fuel pressure switch I believe) that tells the fuel pump that the engine is running (since there is oil pressure) and the switch allows power to the pump.
The ignition switch is NOT wired into the fuel pump circuit directly. Also, it is not an alarm that tells you the key switch is on, it's another oil pressure switch that is normally closed and causes the oil pressure alarm to go off when the key is on and there is no oil pressure.
Yes, you need the oil pressure switch just above the block oil filter boss.

Here is the wiring diagram of the system.