mercruiser engine starts but stalls

[portela16]

I just installed a brand new engine brand new electric pump, a fuel filter, the boat starts but after about 20 seconds it stalls, any ideas of what the problem could be?

 

[westsider97]

Re: mercruiser engine starts but stalls

Timing maybe?? Carb accelerator pump?? Water in bowls, fuel?? I just had to do all three myself and its now flawless.

 

[Ares596ZP]

Re: mercruiser engine starts but stalls

I just went through that, I would suggest takin a sample of the gas. I found mine to be a nice disgusting cloudy color. If that is the case drain your old gas and put in a fresh tank of gas. After that, make sure you timing is set properly, idle is set properly, and your idle mixture is set properly if you have a carbed boat.

I run my idle at 600-700rpms.

To set your idle mixture is easy. Once you get the boat actually running at idle, go ahead and set your idle speed. Get out a small flathead screwdriver and turn the idle screw to the right nice and slow until the engine starts to stutter and immediately go back to the left. Once you reach a point where it stops stuttering turn a half a screw to the left and leave it for now. Check your idle speed again to make sure it is holding. If it stayed where you want it you are done, if not adjust the idle speed and than you are done. Enjoy!

 

[Maclin]

Re: mercruiser engine starts but stalls

Sounds like the fuel pump gets power and runs from the cranking bypass circuit during starting when the key is in the START position but does not get power when the ignition is in the ON position. The carb gets enough fuel to start and run for 20 or 30 seconds while the fuel pump is running during cranking but then runs out of gas.

Check voltage at the fuel pump positive terminal with the key on and engine running (might have to be quick). If no voltage then the oil pressure switch or the wiring to/from that could be the problem. The fuel pump wiring is designed to only get power if the oil pressure switch see oil pressure and turns "on". The oil pressure switch circuit is essentially bypassed during cranking because the pump gets power thru another circuit then.

 

[Don S]

Re: mercruiser engine starts but stalls

Below is a wiring diagram of a Mercruiser electric pump fuel system. To easily check yours, Hook a jumper wire between the two terminals on the oil pressure switch (just above the block oil filter base) With the key in the run position the fuel pump should run. Start it and run it to test that it runs more than 20 seconds. If all is well at that point, replace the switch or clean the terminal ends where the wires connect to the switch.