2001 4.3 Mercruiser carb fires but won't run

[redblur]

It was running great last fall when I put it away. I winterized it (filters, fluids, fogged, etc).

Now I tried to start it for the first time yesterday and once I cranked it enough to get gas to the carb, it fires but stops right sway. I was thinking it was a fuel delivery issue but if I pour a little gas or carb cleaner down the carb it does the same thing.

It fires almost immediately but won't stay running. It's got to be getting some sort of spark since it fires, right?

What really sucks is that it's been sitting in my driveway for 3 weeks but I didn't have the time to get it fired up but didn't think it was a big deal since it's never been an issue before. Now when I was hoping to take it out this weekend there it sits.

Any ideas?

 

[larson176]

Re: 2001 4.3 Mercruiser carb fires but won't run

Hi i may be wrong but i had same issue with mine it was the electric fuel pump relay they seem to die regularly! i would check the dissy cap and leads aswell though good luck

 

[redblur]

Re: 2001 4.3 Mercruiser carb fires but won't run

Isn't an electric fuel pump an MPI thing? I think mine is a mechanical pump.

 

[Bondo]

Re: 2001 4.3 Mercruiser carb fires but won't run

I think mine is a mechanical pump.

Nope,.... They've been electric since the early 90s...

 

[Don S]

Re: 2001 4.3 Mercruiser carb fires but won't run

If it starts and runs for 10 to 20 seconds and then dies, you may have a faulty oil pressure switch that controls the electric fuel pump.
When cranking, the fuel pump gets power from starter solenoid, when the engine starts and oil pressure builds the pressure switch is energized and the power to the pump comes from the switch.

 

[redblur]

Re: 2001 4.3 Mercruiser carb fires but won't run

Thanks for the info about the fuel pump. Good to know.

It doesn't even run 10 seconds. It runs just long enough for my mind to tell my fingers to let go of the key because it started. But Don S., I think you're onto something with the oil pressure switch. I looked the part up and the description says:

* Oil Pressure Switch
* Used For Audio Warning System

And that reminds me that during this debacle the annoying audio warning buzzer hasn't been working all the time. In the entire time I've owned the boat the thing has never failed to go off. But now, a few times I've tried to start the boat, then after it fired I'd turn around to go look at the engine but left the key on. Then, about the time I got back to the engine the buzzer started. I just assumed it was something unrelated but it it's all tied together maybe not.

Where is the switch located?

 

[Don S]

Re: 2001 4.3 Mercruiser carb fires but won't run

What is your engines serial number. Merc list nothing by year. only by SN.

The switch for the fuel pump is not the same one as the audio alarm.

Might want to head up to the Adults only sticky at the top of this forum and download the service manuals for your engine and drive. The wiring diagrams will show you the different switches and senders in your system.

 

[redblur]

Re: 2001 4.3 Mercruiser carb fires but won't run

Engine serial number is 0L697010.

I'm looking through the service manual right now and found its location. Is there way to test the switch? Sorry, if that's in the manual my first pass didn't turn it up.