3.0 mercruiser ran for 5 min good. Then Just died?

[achris]

so the fuel pump in the gas tank or is the one on the block it? Ill take out the filter and see the condition.

There a pump in the fuel tank?

No no no.... No. No pump in the tank! Definitely shouldn't have a pump in the tank. Please tell me there's no pump in the tank....

Chris...

 

[ilove2fixx]

There a pump in the fuel tank?

No no no.... No. No pump in the tank! Definitely shouldn't have a pump in the tank. Please tell me there's no pump in the tank....

Chris...

i dont know. But it doesnt look like it, i open the cover on the ground and i see the tank and from what it looks like it doesnt have a pump just the hoses. I just thought it was like a car and had fuel pump in the tank

 

[j cat]

so the fuel pump in the gas tank or is the one on the block it? Ill take out the filter and see the condition.

take out the spark plugs see if it looks good ...or wet gas on it ..
the carb bowl is the correct adjustment ?
inspect the gasoline to remove the filter ..
also inspect the ignition spark , do not remove the spark plug , put the other spark plug on the block and see if the tip has a good spark..

 

[j cat]

i dont know. But it doesnt look like it, i open the cover on the ground and i see the tank and from what it looks like it doesnt have a pump just the hoses. I just thought it was like a car and had fuel pump in the tank

well I have a 1984 camaro with the fuel pump on the engine . I am the original owner ..

 

[achris]

i dont know. But it doesnt look like it, i open the cover on the ground and i see the tank and from what it looks like it doesnt have a pump just the hoses. I just thought it was like a car and had fuel pump in the tank

well I have a 1984 camaro with the fuel pump on the engine . I am the original owner ..

Cars/boats - Pigs/sheep....
Stop thinking 'car' when working on 'boat'. Different animals. Very often you can't apply 'car' logic, it just isn't the same...

Research what you're working on and understand that. Don't think because you know how a car's put together that a boat is done the same way, because it's just not....

Chris....

 

[TyeeMan]

A mechanical fuel pump can fail very quickly. Back in the day we had a 86 Chevy Blazer, 5.0 V-8, carbureted with mechanical fuel pump on the block. It literally went from running perfectly to barely running at all in the span of a few miles. In my case, the lever that runs off the cam and operates the pump, that lever pivots on a little pin. The hole where the pin went through the actuating lever got all wollered out, so the actual pump stroke was much less than what was needed in order to deliver the correct amount of fuel to the carb.

 

[Rick Stephens]

Test is to stick a pressure gauge in the line between pump and carburetor.

 

[ilove2fixx]

i already checked everything on the electric side that's good.. I did have a hard time with the float pin last month. Im thinking its either the fuel pump or the bowl float needle issue. When i took off the fuel line at the carb gas shot out like it was under a lot of pressure? Is that normal? i think the float needle is stuck ? But that doesnt explian why when i give it a couple of pumps engine runs for sec and dies .

 

[Grub54891]

I'm thinking that if you have a good friend that is familiar with how a boat works, would be a good thing. They could help you out a bit along with us on here.
You stated you had a hard time with the float pin, I would hope you didn't force it and mess it up badly. Not giving you a hard time here, just want to help if I can. To bad you are in California. I'd like to get hands on that thing and get it going for ya.

 

[achris]

But that doesnt explian why when i give it a couple of pumps engine runs for sec and dies .

For that you need to understand at a granular level how the accelerator pump circuit on a carb works... It's to do with the pump plunger fuel well... Suffice to say that the accelerator pump is able to deliver fuel even after the float bowl level is too low for the fuel to be drawn up through the discharge holes...

Chris....

 

[Scott06]

Test is to stick a pressure gauge in the line between pump and carburetor.

This - dump a little fuel down carb measure fuel pressure for a few seconds while it is running

 

[ilove2fixx]

I'm thinking that if you have a good friend that is familiar with how a boat works, would be a good thing. They could help you out a bit along with us on here.
You stated you had a hard time with the float pin, I would hope you didn't force it and mess it up badly. Not giving you a hard time here, just want to help if I can. To bad you are in California. I'd like to get hands on that thing and get it going for ya.

I appreciate all of your guys input and help. You guys have so much patience, I applaud that. This is my 3rd boat and i have rebuilt couple carbs before. Just this one is giving me a hard time. Maybe i did mess up the needle or maybe the pump is bad.. I did Pull the fuel filter and other then the abnormal color of the gas it wad pretty clean in there. No water or gunk.

 

[ilove2fixx]

For that you need to understand at a granule level how the accelerator pump circuit on a carb works... It's to do with the pump plunger fuel well... Suffice to say that the accelerator pump is able to deliver fuel even after the float bowl level is too low for the fuel to be drawn up through the discharge holes...

Chris....

i understand the carb can store fuel but what i dont understand is how come the engine doesnt draw the fuel out and run even for a second with that stored fuel? And why does it run only when i pump it?

 

[achris]

i understand the carb can store fuel but what i dont understand is how come the engine doesnt draw the fuel out and run even for a second with that stored fuel? And why does it run only when i pump it?

For the answer to that question, read THIS post.

Chris...

 

[j cat]

i understand the carb can store fuel but what i dont understand is how come the engine doesnt draw the fuel out and run even for a second with that stored fuel? And why does it run only when i pump it?

so the carb throttle handle manual pumps gasoline into the engine ,, then it starts ,, then the carb ports have a goop in it .. remove the mixture screws use a carb cleaner to spray the into the screw holes with a plastic straw.. see if it works .........
I use marine gasoline additive all the time ..I take out gasoline in the fall out of the tank .decades ago alcohol has a mess in gas then many vehicles sit a year or so then the engine does not run ..

 

[achris]

i understand the carb can store fuel but what i dont understand is how come the engine doesnt draw the fuel out and run even for a second with that stored fuel? And why does it run only when i pump it?

Ok, carbs 101.

There's a reason why you set the float to a particular height. It's so the right fuel pressure 'head' is applied to the ports (idle and progression) and the main discharge in the venturi. Set the level too high and your engine will run rich, too low and it'll run lean. Without the fuel pump refilling the fuel bowl/float chamber, the level in the fuel bowl drops, and that causes the mixture to lean out. It will continue leaning out until the engine can't fire it, at which point the engine will stop, despite there being fuel left in the carb. It's just not enough to produce a strong enough mixture to fire and sustain the engine. Now, the accelerator pump fuel well sits slightly lower than the bottom of the float chamber, so any fuel left in the chamber will collect in the acc. pump well. That's why, when you pump the throttle (and activate the acc. pump) the engine gets a couple of shots of fuel, and that's enough for it to run for a few seconds. But it's only running on the fuel shot into the intake by the acc. pump, it's not drawing any of the remaining fuel in the float chamber, because it can't (the fuel level is way too low).

Chris.........

 

[ilove2fixx]

Ok, carbs 101.

There's a reason why you set the float to a particular height. It's so the right fuel pressure 'head' is applied to the ports (idle and progression) and the main discharge in the venturi. Set the level too high and your engine will run rich, too low and it'll run lean. Without the fuel pump refilling the fuel bowl/float chamber, the level in the fuel bowl drops, and that causes the mixture to lean out. It will continue leaning out until the engine can't fire it, at which point the engine will stop, despite there being fuel left in the carb. It's just not enough to produce a strong enough mixture to fire and sustain the engine. Now, the accelerator pump fuel well sits slightly lower than the bottom of the float chamber, so any fuel left in the chamber will collect in the acc. pump well. That's why, when you pump the throttle (and activate the acc. pump) the engine gets a couple of shots of fuel, and that's enough for it to run for a few seconds. But it's only running on the fuel shot into the intake by the acc. pump, it's not drawing any of the remaining fuel in the float chamber, because it can't (the fuel level is way too low).

Chris.........

i see , thanks for that Chris. So what to do next Chris , should i redo the carb or change /fix the fuel pump ?

 

[achris]

Disconnect the fuel line from the carb. Attach a length of flexible tubing (local hardware shop should have some tygon tubing). Disable the ignition (something like... remove the wire to the points, or ground the wire that runs from the coil - to the shift interrupt switch, or put a small jumper wire between the terminals on the interrupt switch. DO NOT just disconnect the HT lead between cool and distributor. All that does is ensure you have an open spark). Put the other end of the tubing into a suitable container and crank the engine. You get a good stream of fuel, pull the carb. No fuel, pull the pump.

Chris....

 

[havoc_squad]

Disconnect the fuel line from the carb. Attach a length of flexible tubing (local hardware shop should have some tygon tubing). Disable the ignition (something like... remove the wire to the points, or ground the wire that runs from the coil - to the shift interrupt switch, or put a small jumper wire between the terminals on the interrupt switch. DO NOT just disconnect the HT lead between cool and distributor. All that does is ensure you have an open spark). Put the other end of the tubing into a suitable container and crank the engine. You get a good stream of fuel, pull the carb. No fuel, pull the pump.

Chris....

Since the OP video showed it is using the standard Delco EST ignition system, disabling the ignition is even easier, just need to pull the purple 12V & gray tach connector. That will kill the 12 V power to the coil, no need to ground anything. Just need to secure the connector from touching ground.

 

[ilove2fixx]

Since the OP video showed it is using the standard Delco EST ignition system, disabling the ignition is even easier, just need to pull the purple 12V & gray tach connector. That will kill the 12 V power to the coil, no need to ground anything. Just need to secure the connector from touching ground.

Disconnect the fuel line from the carb. Attach a length of flexible tubing (local hardware shop should have some tygon tubing). Disable the ignition (something like... remove the wire to the points, or ground the wire that runs from the coil - to the shift interrupt switch, or put a small jumper wire between the terminals on the interrupt switch. DO NOT just disconnect the HT lead between cool and distributor. All that does is ensure you have an open spark). Put the other end of the tubing into a suitable container and crank the engine. You get a good stream of fuel, pull the carb. No fuel, pull the pump.

Chris....

ok thanks guys will try that now!