Mercruiser 4.3L Fuel Starvation with low tank

[HumboldtHullscraper]

Hi all,
New to the forum. I've got a 1997 Bayliner Capri 2050 with a 4.3l Mercruiser. The problem I've been trying to figure out is that when my tank is ~1/3 left the boat will sputter, stall, and eventually leave us stranded until I fill it up again. For example last time it happened the tank still had 9gallons left in it (I have a 26 gallon tank). I keep up on regular maintenance items like fuel filter, oil changes, spark plugs, etc. And I also consider myself pretty mechanically inclined, but boat work is a new ballpark for me. Any help/advice would be appreciated. Do you think I need to test the fuel pump? My dad thinks there is a "fuel sending unit" in the tank that could be bent, therefore not picking up the last 1/3 of the tank. Thanks in advance for any help!

 

[HumboldtHullscraper]

Okay so i figured out the fuel sending unit just tells the gauge what fuel level you are at. If that was damaged it wouldn't affect the actual supply of fuel to my engine right? Any ideas as to what it could be?

 

[nola mike]

Correct. There's no in tank fuel pump or anything. I assume that you know for sure that there's still 9 gallons in the tank and not going by the fuel gauge. Otherwise all I can think of would be a break in the in tank pickup line. Could be wrong, but I don't think another upstream obstruction would be enough to do that. Next time it happens, I'd disconnect the line at the carb, see if you're getting fuel. If not, disconnect before the pump and put suction on the line, see if you can draw gas up the line.

 

[HumboldtHullscraper]

Thanks for the response.

Yeah I know for sure there was 9 gallons because I could only put 17 in to fill it up, similar situation with slightly different numbers the other times it has happened. I'm taking it to the lake for the 4th of July and would like to fix the problem before then. If I remove the fuel pickup line from the tank is there some way I should test it for cracks/leaks other than a visual inspection?

 

[Rick Stephens]

You know for fact that it holds 26 gallons? As in you have put that much in it?

 

[HumboldtHullscraper]

Yes I know it holds 26, before this problem I have put as much as 25.3ish gallons in it.

 

[nola mike]

Thanks for the response.

Yeah I know for sure there was 9 gallons because I could only put 17 in to fill it up, similar situation with slightly different numbers the other times it has happened. I'm taking it to the lake for the 4th of July and would like to fix the problem before then. If I remove the fuel pickup line from the tank is there some way I should test it for cracks/leaks other than a visual inspection?

If you get no resistance with suction, and no fuel return, then that would be it I think (or it's somehow not positioned correctly). You can remove the fuel gauge sender to get a look inside the tank

 

[HumboldtHullscraper]

Okay I'll give it a look tomorrow when I'm off work and post the results. Thanks for your help!