4.3 mercruiser dieing issues

[Saris222]

1994 4.3 mercruiser. Has a Weber carb on it. Took boat out for a test run this morning. Ran good idled smooth. Fired right up even when cold. After 30 minutes boat was surging like it was running out of gas. Later in the afternoon I filled the tank I assume too much cause gas shot.out the siphon tube. Got boat to lake. Started and ran for about 5 minutes. The stuttered till it shut down. Will start for a second or 2 after trying several times over a period of 10 minutes to start it. If I can get it to start in neutral revived up it'll stay running. Put it in gear and it sputters till it dies. I opened fuel door and it sucked air in. So left it open. Boat started but still dies and still won't start everytime I turn the key. Frustrated. Just boat this boat after a successful test run. Also if I leave the key in run position with out it running an alarm sounds and won't stop.

 

[Saris222]

Sorry for the miss spelled words. Didn't proof read before posting.

 

[Bt Doctur]

I opened fuel door and it sucked air in. So left it open.

Clogged fuel tank vent

The stuttered till it shut down. Will start for a second or 2 after trying several times over a period of 10 minutes to start it.

water filled fuel filter will do that

Also if I leave the key in run position with out it running an alarm sounds and won't stop.

Correct, there is no engine oil pressure and the alarm will sound with the key on

 

[Saris222]

First time owning a boat. I'll check that tomorrow.

 

[Saris222]

Could the over filled tank be the issue on the vent tube?

 

[alldodge]

Could the over filled tank be the issue on the vent tube?

No, that will not cause the issue.

Take the fuel filter off and dump the contents into a baggie. Look for anything that is not clean gas. If there is water in it, then there will be a separation

Listen for the fuel pump, is it running when cranking the motor and after it starts does it still run?

 

[jrs_diesel]

Overfilled, not usually. The vent line is one of the two smaller hoses on your gas tank. The high end of the vent line will go up to the top of the filler neck, or its own vent fitting. If it is part of the tank filler neck, the cap will have some way of allowing air in, and not let any fuel splash out. The fill neck and vent line could be full of fuel, but as long as the vented cap works, then that won't be an issue.

So your venting problem could be one of two things depending on where your vent line goes. If it's part of the filler neck, your vent cap is either not working or you have a non vented cap installed. If it's by itself, it is likely plugged, most commonly by insects (spiders and/or mud dauber wasps).

Hope this helps

 

[Saris222]

Alright I'll dump the water separator, just spoke with someone else that said you also prime the new filter when. Is this needed?

 

[alldodge]

Alright I'll dump the water separator, just spoke with someone else that said you also prime the new filter when. Is this needed?

Was their anything in the filter except clean gas?

Always good to fill the filter with fresh gas before installing

 

[Saris222]

I primed it. Filter had a little trash in it. Replaced with new. Dumped it after an hour of running. No trash this time. The surging issue was solved with replacing the coil. But now the boat won't get over 4k rpms. Before the surging it had no issue getting up to 4800. Not really sure what's the problem now. Runs perfect other than not getting over 4k rpms. Ran it for 2 hours yesterday. Checked the rotor and cap. They look brand new, plugs seem fine. Same with wires, tank is venting properly. Fuel pressure is steady at 7 psi. Not really sure where to go from here

 

[alldodge]

Motor was surging, changed filter (crud in it) and all is good except will not get over 4K rpms. Everything is perfect except rpms, guess its the carb would be my next thought

 

[Saris222]

With motor off I did hear a bubbling hissing sound from what I assume was the accelerator pump. I was told an edelbrock carb kit pn 1477. Is a good kit to use on the 4 barrel webers. Any experience with this?

 

[alldodge]

With motor off I did hear a bubbling hissing sound from what I assume was the accelerator pump. I was told an edelbrock carb kit pn 1477. Is a good kit to use on the 4 barrel webers. Any experience with this?

Need to know the part number of your carb. Look for the number stamped on its side

 

[Saris222]

Alright