Fuel dripping when the filter is removed. Is anything wrong with pump or carb?

babikov

Petty Officer 2nd Class
Joined
Sep 3, 2009
Messages
113
Hi,

While winterizing my boat I noticed something different compared to the previous years.

Namely, when I removed the fuel filter (to replace it) I noticed that gasoline started dripping from the filter connection spot. I tried to absorb it with paper towels, and had a few towels wet. May be an ounce or less overall of the fuel. In five minutes it stopped. Looks like the fuel from the fuel pump, the line to the carb, and may be the carb itself was simply going down and dripping.

I never saw that in the past. I always saw the filter full of gas, but never the gas dripping. Isn't there any anti-siphon valve that prevents the fuel going back down to the tank? In fact, it is quite unsafe, I think, to have several paper towels wet in gasoline around the boat... But my major concern is this: Isn't it a sign of the failing fuel pump, or some other problems, for example, with the carburetor?

I noticed this year that engine was difficult to start. I had to crank it quite a bit, and then it would start suddenly and run smoothly. Almost like if there was no fuel at all, and then when it is there it would fire up right away. I cleaned the carb intake using a spray, looks clean to me. I also checked the fuel pump, it makes an audible hum when the switch is bypassed. But, may be it is just not pumping well enough, and is leaking, and that is exactly what I see?

Any opinion about this? Thanks. My boat numbers are: 1993 4.3LX/V6 serial number 0F0244564; the transom is 0F058634; the drive is 0D886515 (Alpha One Gen II).
 

Fun Times

Moderator
Staff member
Joined
May 16, 2009
Messages
8,842
It's very possible you may have a stuck open internal check valve inside the fuel pump allowing the fuel to drop back down to the filter. Yes that could contribute to a hard starting problem like you've recently noticed. The below links are of some fuel pump trouble shooting tricks you could try doing before considering buying/trying a new pump. The quote is one trick of a few found inside the links.
NOTE: On low pressure boost or carburetor fuel pumps, plugging the outlet, and then running the pump against this blockage for a short time can loosen the stuck internal check valve.
Electric Fuel Pump Troubleshooting - Marine Mechanic

Electric Fuel Pump Check Valve Sticking
REQUIRED FUEL INLET FITTING REPLACEMENT ON WEBER CARBURETOR
EFI / MPI Fuel Pumps With Low Pressure
-Stainless Steel Electric Fuel Pumps

Remember the links are just ideas for you to get to know the workings of the pump, they don't necessarily mean you have one of these exact problems as none fall within your serial number range.
 

Watermann

Starmada Splash of the Year 2014
Joined
Jan 12, 2013
Messages
13,753
I would think gravity would allow the line to back drain once the system is opened up and having an ounce of fuel drain out doesn't sound like a problem to me. Maybe next time put a small pan under the drip. What I do is pre-fill the new filter and have it ready to install when the old one comes off.
 

babikov

Petty Officer 2nd Class
Joined
Sep 3, 2009
Messages
113
Thanks to all who responded. A related question about the fuel pump. The numbers on it are 952 0203A 1. These do not correspond to any part number in the repair manual. Is this just an aftermarket part?

I checked the fuels pumps online. Some are high pressure, others are low pressure. How do I know what to buy? It looks like my part number is 805656A 2, replaced by 861155A 6. Any thoughts? Thanks.
 

Fun Times

Moderator
Staff member
Joined
May 16, 2009
Messages
8,842
Thanks to all who responded. A related question about the fuel pump. The numbers on it are 952 0203A 1. These do not correspond to any part number in the repair manual. Is this just an aftermarket part?
Since there is an A1 at the end of the number, it's most likely an internal part number to Mercruiser as they sometimes use different numbers from what is found on the actual part vs what you see in the parts catalog. It's best to go by your engine serial number to obtain the correct/latest part/s / part numbers.

I checked the fuels pumps online. Some are high pressure, others are low pressure. How do I know what to buy? It looks like my part number is 805656A 2, replaced by 861155A 6. Any thoughts? Thanks.
Yours is a lower pressure system. Just for reference, the latest part number is the A6 number you found. An aftermarket alternative from sierra marine would be 18-7326 available from iboats as well. http://www.iboats.com/Electric-Fuel...1557639--session_id.393819735--view_id.172625

Please keep in mind that my post above is only a theorized possibly and not an actual recommendation to automatically buy and install a new expensive fuel pump in hopes that it may change the situation you seem to be having.

Some of the tests found in the information posted above may help to narrow down some possibilities should there actually be something wrong with the pump internally was more of the goal. I'd hate to see you spend that kind of money for nothing. Some leakage is normal such a light to medium drip..drip..drip to eventually a stop when you remove the filter. But a light trickle for say over 30 seconds indicates the possibility of the fuel system not holding properly someplace.

An old trick some have done to resolve some internal issues inside the fuel pump is to add a small amount of marvel mystery oil to the fuel tank or filter to help lube the inside of the pump.

Test and spend wisely should be the main goal.

Good luck.
 
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