I need help, boat runs rough and stalls. I pumped new gas and lots more.. I need help

[Bayliner3.0]

1997 Mercruiser 3.0LX engine. Manual Fuel Pump, carburetor.
Boat ran great last time out. I pumped about 1/2 tank of new gas (10 Gal) got to the lake and would barely run, stalled off throttle or shook like crazy trying to stall.

Old boat I thought tune up ignition:
Replaced plugs, wires, cap, and rotor.
Fuel pump has always worked, but was original so I replaced it too.
I checked the ANTI SIPHON VALVE on the gas tank and it was clean and ball moving normally.

Started the boat after tune up and was very hard to start. Kept trying and would start then die start then die. I had to pump the throttle to get it to start each time. Choke was wide open

Started again and reved it to about 1500-2k and it smoothed out and then would hold idle. But it seemed to just run a little funny. When I revved it up it was much more smooth on the throttle than normal. I am guessing the Ignition tune up was working great!

What am I missing? Could I have pumped in bad gas?? I mean I hear about it online, but never met anyone who has ever had bad gas from the pump (in modern days).

Where should I start? I am thinking check fuel pressure, hook up a seperate fuel tank with good gas. Is there anything else I should check?

 

[Chris1956]

Does the choke plate close when the engine is cold? It sounds like the accelerator pump is working, but you should verify.

What do the spark plugs look like?

 

[FLATHEAD]

What am I missing? Could I have pumped in bad gas?? I mean I hear about it online, but never met anyone who has ever had bad gas from the pump (in modern days).

Not at all saying it’s what’s causing your issue but bad gas still happens these days.

NJ gas station was found to have 78% water in its fuel that left over a dozen drivers stranded—again

The Conoco gas station in Camden, NJ was found to have up to 78% water in its fuel after over a dozen drivers filled up their tanks there and then broke down. This is the second time this happened there.

www.nbcphiladelphia.com

 

[alldodge]

Boat ran great last time out.

If last time was not more then 6 months ago then I would look at carb rebuild

 

[cyclops222]

Classic case of BAD gasoline. You are lucky. Are all gas tank openings covered with a designed cover ??? If not ? a rag stuffed in is how water gets into the tank. Does the motor have ...FULL original covers ? Remove & look at sparkplugs. Replace with the CORRECT TYPE .... Not with the ones you find if they may be incorrect.

 

[Bayliner3.0]

Does the choke plate close when the engine is cold? It sounds like the accelerator pump is working, but you should verify.

What do the spark plugs look like?

I am going to check the choke plate this morning when I get started on it. Spark plugs were brand new at the time of start, and the plugs I replaced looked pristine. 1st start. Recommended plugs from the manual.

 

[Bayliner3.0]

If last time was not more then 6 months ago then I would look at carb rebuild

Had it out maybe 4 weeks prior.

 

[Bayliner3.0]

Classic case of BAD gasoline. You are lucky. Are all gas tank openings covered with a designed cover ??? If not ? a rag stuffed in is how water gets into the tank. Does the motor have ...FULL original covers ? Remove & look at sparkplugs. Replace with the CORRECT TYPE .... Not with the ones you find if they may be incorrect.

Gas tank has a plastic click close cover it is the factory cover. The engine has the original factory cover.
Spark plugs are brand new this was the 1st start with them. They are the factory recommended spark plugs.
I did not think about water in the gas tank, but I don’t know how it would have gotten there. Are you saying I should put a rag in the fill to stop water from getting in?
Well I will test gas and fuel pump pressure, then maybe consider the carb rebuild. I am sure the carb has not been cleaned/rebuilt in a while.

Any ideas on how to pump out the gas or check for water?? 20 gallons in the tank right now..

 

[cyclops222]

DO NOT use a rag !! Use the original cover as usual.

 

[alldodge]

Don't pump the gas out, test first

First note that just because someone post something on your thread does not mean they know what the problem actually is. We all (including my self) are guessing right now. You need to test first, this will indicate what is "actually" happening.

If you want to check the gas, disconnect power going to coil. If you have a kill switch pulling it will do same thing.

Empty fuel filter into clear container and see if there is anything but clean gas. If you have a pump and filter combo, catch all the fuel when opening the filter

Look for anything other then pure gas. If water is there you can clearly see it

 

[Bayliner3.0]

DO NOT use a rag !! Use the original cover as usual.

Ok thanks for clearing that up.
I thought you might have meant put a rag under the cap to soak up water that might be getting in so it did not get in the tank..
Rags = No no

 

[Bayliner3.0]

Don't pump the gas out, test first

First note that just because someone post something on your thread does not mean they know what the problem actually is. We all (including my self) are guessing right now. You need to test first, this will indicate what is "actually" happening.

If you want to check the gas, disconnect power going to coil. If you have a kill switch pulling it will do same thing.

Empty fuel filter into clear container and see if there is anything but clean gas. If you have a pump and filter combo, catch all the fuel when opening the filter

Look for anything other then pure gas. If water is there you can clearly see it

Ok, great advice. I take all info gratefully, but one step at a time for sure starting with the most simple. I was only asking how to empty the tank if I found water.
I have the pump filter combo and NO water seperator. I will check the filter bowl for water makes perfect sense, also the new fuel pump pressure just to see, I am curious even if it is not the problem.
I just poured HEET in the tank to try and bond any water to it so it burns easier. It rains a lot where I live and the boat is stored outside under a fabric cover. So I guess water might get in there through constant humidity…?...

 

[Bayliner3.0]

So the fuel pump filter bowl had perfectly pure gasoline, no water or anything otherwise.
I did discover my choke is stuck open. When I move the throttle to wide open I can move the choke but the spring is not doing anything. Time to take apart the choke I guess.
Any advice or direction to a previous post on chokes or bad spring or cleaning choke?
Could a choke stuck open cause these running issues?

 

[alldodge]

The choke should only be wide open when the motor is warm. If motor has not been started today then it should most likely be closed unless it's hot were your at

Would be good to know your motor serial number just to know everything about your motor?

discover my choke is stuck open.

Knowing this means you most likely have something like the 2GC carb.

You mentioned about how you kept the motor running. With it running even 5 minutes it should have warmed up enough to run mostly ok with the choke being open. My guess still goes back to something has gotten into the main jet(s) of the carb and it's not getting enough fuel. Either that or the fuel pump is failing.

Check your oil level and if it's above normal then the fuel pump diaphragm has ruptured and gas is mixing with the oil. If oil level remains the same then you could check pressure by installing a Tee fitting between the carb and fuel pump.
https://www.harborfreight.com/fuel-pump-and-vacuum-tester-62637.html

If fuel pressure is good then it's the carb.

If it was mine I would remove the top of the carb. When top is removed the bowl should be full almost to the top. The inside of the float bowl should be clean

 

[Bayliner3.0]

The choke should only be wide open when the motor is warm. If motor has not been started today then it should most likely be closed unless it's hot were your at

Would be good to know your motor serial number just to know everything about your motor?


Knowing this means you most likely have something like the 2GC carb.

You mentioned about how you kept the motor running. With it running even 5 minutes it should have warmed up enough to run mostly ok with the choke being open. My guess still goes back to something has gotten into the main jet(s) of the carb and it's not getting enough fuel. Either that or the fuel pump is failing.

Check your oil level and if it's above normal then the fuel pump diaphragm has ruptured and gas is mixing with the oil. If oil level remains the same then you could check pressure by installing a Tee fitting between the carb and fuel pump.
https://www.harborfreight.com/fuel-pump-and-vacuum-tester-62637.html

If fuel pressure is good then it's the carb.

If it was mine I would remove the top of the carb. When top is removed the bowl should be full almost to the top. The inside of the float bowl should be clean

0k148873 serial

Well the choke was pinned under throttle arm/lever it would not move. I had to move throttle to full open just to get it to close. Then manually moving the choke it would not return on its own. I move it open it stays open I move it closed it stays closed.

I just installed a brand new fuel pump with the spark plugs, wires, cap, and rotor. This was the first start for all of it.

FYI Oreileys auto parts has a fuel pressure test kit for loan. It comes with a GM adapter that fits right inbetween the fuel line and carb and apressure guage.

I am going to pull the carb and clean it you might be right and it couldn’t hurt. I have a carb kit I have been meaning to use. The plug wires cap and rotor were labeled 1997 so the carb may not have ever been touched. Probably filthy.

But it would seem that the choke is the issue. If it were stuck open would that cause stalling/ rough start and idle?

 

[alldodge]

But it would seem that the choke is the issue. If it were stuck open would that cause stalling/ rough start and idle?

Yes if the choke is stuck open then there would be some issues for the first so many minutes. Once it starts to warm up then choke is not needed

You said it was running fine a few weeks ago, so the initial start issue could have been caused by a broke choke spring.

 

[Bayliner3.0]

Yes if the choke is stuck open then there would be some issues for the first so many minutes. Once it starts to warm up then choke is not needed

You said it was running fine a few weeks ago, so the initial start issue could have been caused by a broke choke spring.

Right, which makes sense as once I kept trying to start it for 10 min checking this and that and then held it at 1500-2k rpm and it was able to idle, but a little rough.
I am thinking a carb clean and rebuild can’t hurt so here we go.
Not sure if the choke is serviceable or has to be replaced yet.

I think I had a couple/few issues here. Choke, semi dirty carb, and initially there may have been a loose spark plug wire (before I replaced ignition parts).

 

[Chris1956]

The choke is immobilized by the throttle under closed and open settings. Loosen the screws around the choke black plastic housing. Open the throttle and turn the choke housing until the choke just closes....no more.

If the choke plate moves with the choke housing, the mechanism is likely intact. Some chokes are electric as well. The test is the same. When the engine is warm, the choke plate is wide open.
Tighten the choke housing screws. Start the motor (presumes that the rest of the motor is good) and let her warm. The choke should open, You will need to rev the motor to release the choke plate.

 

[Bayliner3.0]

The choke is immobilized by the throttle under closed and open settings. Loosen the screws around the choke black plastic housing. Open the throttle and turn the choke housing until the choke just closes....no more.

If the choke plate moves with the choke housing, the mechanism is likely intact. Some chokes are electric as well. The test is the same. When the engine is warm, the choke plate is wide open.
Tighten the choke housing screws. Start the motor (presumes that the rest of the motor is good) and let her warm. The choke should open, You will need to rev the motor to release the choke plate.

Thanks for the info. My carb is electric choke and it seems like it is really dirty or corroded it will not spring closed on its own.
I took the carb off and have started tearing it apart to clean (it is pretty dirty inside). Some gas got on the choke valve and it started to move a little better. I can tell the spring is intact.. So we will see after the rebuild if the choke moves freely or not. Amazon has a knock off replacement for $15 if I need it too.

 

[alldodge]

(it is pretty dirty inside).