Leaking fuel at carb. HELP!

[timharper89]

1987 4.3 mercruiser alpha one. I just ran the boat about 10 miles up river and when I stopped, I noticed a strong fuel odor. There is fuel making puddles on the side of the engine ,and I heard a bubbling noise. There is fuel bubbling inside the carb. I will link pictures and video. HELP!!! https://photos.app.goo.gl/Hr1UdNeziswxKqgk7

 

[Scott Danforth]

stop using your boat until you fix it

by the lack of the clear fuel line to the brass elbow, someone has replaced the mechanical fuel pump with an electric pump. that fuel pump is not tied into an oil pressure switch

your needle and seat are not stopping fuel and you are literally pumping fuel into your motor with the motor not running. this is creating a bomb.

get a tow back to the ramp, fix the carb, and address your fuel pump.

 

[timharper89]

The fuel drained out of the carb as it was sitting, so it's not pumping author the motor running. It is definitely an electric pump though and runs with the key "on". Thinking about it, it doesn't turn off on its own. Not sure if that's what you meant. So what do I do with the pump?

 

[Scott Danforth]

properly installed electric fuel pumps are wired to an oil pump safety switch so they do not run when the motor isnt running and they only run during cranking and when the motor is running.

the fuel drained out the carb, and into your cylinders, washing the oil off the cylinder walls. it then dilutes the oil with gasoline taking out your engines bearings.

I would simply take out the incorrectly installed electric pump, and install the correct mechanical pump into the motor. you will need to also go thru your carb and replace the needle and seat. you will need to change oil before running your engine.

 

[timharper89]

Any idea where I can find what fuel pump I need?

 

[Bondo]

Any idea where I can find what fuel pump I need?

Ayuh,.... The one you've got might be fine, just wired incorrectly,.....

The carb needs rebuildin', regardless,..... the needle, 'n seat should stop the gas flow,.....

 

[timharper89]

So even with the pump always pumping, the carb should regulate it just fine?

 

[timharper89]

Or do I need to properly wire it? I don't know how to do that. Is there a manual for something like that?

 

[Bondo]

Or do I need to properly wire it? I don't know how to do that. Is there a manual for something like that?

Nope,..... But it's been explained in threads right here at iboats, I'm guessin', tens of thousands of times,.....

It's not all that complicated if yer at all, Handy,......

 

[timharper89]

I'm fairly handy, not necessarily experienced though, but apparently my searching skills are not great. Been looking all evening and morning and haven't been able to find any specific info on how to wire an oil pump safety switch. Do I need a relay? Do I need a marine switch, or is that something I can grab at the auto parts store?

 

[AlabamaNewbie]

Before you replaced your bellows, shift cable, etc - did you run the boat on water? Or is this a "new" purchase and first time out with it?

If you ran it before without issue, then I'd look back around the engine and find the wire you knocked loose fighting with your shift cable. If this was the first time you ran it, I'd go back and look for the wire you knocked loose fighting with your shift cable and if you don't find one, then figure out what is wired wrong.

 

[timharper89]

I have run it before. It's always died at idle since I bought it, which was recently. I've had it out about 5 times. Twice five I did the bellows/shift cable. My guess is the new prop played a role. Prop that came with the boat was too much pitch (23) for the boat/motor, thus making the motor work a bit harder and using the excess fuel that was pumped into it. Got a new prop (19 P), and noticed I could keep speed and plane at much lower throttle allowing the fuel to build up more quickly. This is also the longest I've run the motor continuously since I got the boat...about an hour straight. Other times if had it out we did skiing, swimming, and just hanging out. My bet is this is the big difference. The pump has always continuously run with the key in the "on" position. I didn't realize it was gong to flood the carb.

 

[timharper89]

So usually you'd run the engine you heat it up before changing the oil. I'm assuming I would NOT do that in thet case, is that correct? Is there anything more than a standard oil change I'd wanna do to clear out the gas?

 

[Bondo]

Is there anything more than a standard oil change I'd wanna do to clear out the gas?

Nope,.......

The fuel pump always runs continuosly, so long as the motor is Runnin',.....
The carbs needle, 'n seat stops the flow of gas into the carb,.... (ya might need a carb rebuild)

An electric fuel pump is powered by a wire from the outer most tiny terminal on the starter's solenoid, when startin' the motor,.....
When the motor is runnin', it's powered by the ignition circuit, through an oil pressure switch, so when the oil pressure drops below 2 or 3 psi, the fuel pump is shut-off,....

 

[timharper89]

I am just finishing up rebuilding the carb. I didn't see anything that looked obviously wrong with with needle, but the float was pretty far out of spec. The needle also didn't use a spring. Not sure if that will make a difference. There was a missing check ball behind the accelerator pump spring. I'm not sure what that would cause, but the rebuild kit had a new one.

As far as the pump, there is definitely no oil pressure safety switch installed. It is constantly running as soon as the key is in the "run" position. I traced the wires as well to check. So far from my research I think I need to get a t adapter for the oil pressure light for the switch, wire the switch to the fuel pump, starter solenoid and ignition line...is that right?

 

[timharper89]

So I've rebuilt the carb, soaked it, cleaned it, blew it dry. Checked the float, adjusted it to spec. Just installed it (haven't installed the oil pressure switch yet) just waned to check it out, and turned the key on to let the pump send gas to it. The barrels are immediately filling up with gas again. What's the deal? What am I missing ?The needle and today should stop gas from filling the barrels, right? I'm a bit stuck.

 

[AShipShow]

Thinking you might want to check your fuel pressure... might be overpowering the needle and seat.

 

[andrewterri]

If I understand your post correctly you have an electronic fuel pump hardwired in without a return line. so it will not matter at what PSI you N/S are opening closing because there is nowhere for the fuel to go that is being pumped in. Someone mentioned in the beginning of your post that you do not have the clear line on your carb. That clean line is a overflow return to the mechanical fuel pump your boat came with. From my limited understanding, you are over powering you float as well as you N/S without a return line so there is no where for the fuel to go. Someone correct if I'm wrong but I bet that's your problem. And yes, that is creating a bomb. make sure your running your blower(s) while your working on it. Make sure the blower pickup line is mounted down low. Fuel vapors are heavier than air and sink. We just had a 34' cruiser blow up at the marina. Split the boat in half and sent several people to the burn unit.

 

[timharper89]

Thanks. I'll check that tomorrow. Just went and got a fuel pressure gauge from o'reilly's as a loaner. As for a fuel pressure regulator, is there a difference between a marine and one for a car? Can I use any regulator that keeps the pressure to spec or are there uscg requirements or something for the regulator? The extra line into the carb, as I understand, is in case a mechanical fuel pump diaphragm fails. It foods the motor and kills it. The electric fuel pump doesn't have a need for that extra line.

 

[andrewterri]

Timharper89, I was wrong. I just went and looked up the diagram and you are correct. That clear line is not a return. I did not see a passage way from the float bowl to the clear line.