Mercruiser 5.7 was running for 15 minutes at idle , then died ???

[mikethepike]

My beloved 1971 30 Gibson houseboat has super low hours as we use it for a floating cottage here in Michigan. It always ran fine--until today

Today I started it up and let it run for 15-20 minutes at idle before I went to take it out to the hoist for the season. It all of a sudden died. It will start back up briefly like it wants to stay running , but wont and kinda burps out the carburetor

I have an beer can sized inline filter 3' before the water / fuel separator..both were checked (very little sediment in the in line filter and no water in the water /fuel separator) ... We tried a few more times--SAME THING

Coil?

This summer replaced: cap / rotor, plugs, oil change, fuel pump and (bent) fuel pump push rod and water pump .

 

[Bondo]

Ayuh,..... Start at the beginin',.... Does it have Fuel,..?? Fire,..??

To check for Fuel, pull the flame arrester off the carb, 'n while lookin' down the open throat(hold the choke plate open) of the carb, pump the throttle,...
Ya ought see 2 strong streams of gas shootin' down the venturis from the acc. pump,....

For Spark, is the Power at the coil's (+) tiny terminal, with the key "On",..??
If so, pull the coil wire outa the distributor cap 'bout 1/2", 'n turn it over on the starter,... Sparkin' at the wire,..??

 

[mikethepike]

Ayuh,..... Start at the beginin',.... Does it have Fuel,..?? Fire,..??

To check for Fuel, pull the flame arrester off the carb, 'n while lookin' down the open throat(hold the choke plate open) of the carb, pump the throttle,...
Ya ought see 2 strong streams of gas shootin' down the venturis from the acc. pump,....

For Spark, is the Power at the coil's (+) tiny terminal, with the key "On",..??
If so, pull the coil wire outa the distributor cap 'bout 1/2", 'n turn it over on the starter,... Sparkin' at the wire,..??

Thank you for getting back

Yes to all of above . Seems to be a fuel delivery problem with the carburetor . as it will start for a second and then die. 3 outta 5 five times it will run for 3 seconds then die

I checked all filters for clogging, the tank for vapor lock and vent for clogging. Im really stumped.

 

[alldodge]

With the key ON check to see if you have 9 to 12V at the coil

 

[garbageguy]

maybe the anti-siphon valve?

 

[Bondo]

Seems to be a fuel delivery problem with the carburetor . as it will start for a second and then die. 3 outta 5 five times it will run for 3 seconds then die

Ayuh,.... Is the motor original, with a mechanical fuel pump,..??

If so, I'd think the ignition might be dyin' on ya,....

Like AD asks, 'n I did before, is there power at the coil's (+) terminal with the key "on",..??
'n does it still have power, when it dies,..??

 

[mikethepike]

Ayuh,.... Is the motor original, with a mechanical fuel pump,..??

If so, I'd think the ignition might be dyin' on ya,....

Like AD asks, 'n I did before, is there power at the coil's (+) terminal with the key "on",..??
'n does it still have power, when it dies,..??

Yes, motor is original with a new mechanical fuel pump and pump rod

I'll have to check the power running and when it dies.

I pulled the boat for the season yesterday as I was soo frustrated .

 

[Bondo]

I'll have to check the power running and when it dies.

Ayuh,... That where the diagnosis starts,....

No power, look to the key switch, or loose, broken, corroded wirin', in between,...

Power, move on to the ignition system,...