3.0 Merc Fuel Pump Question

[lgrouper03]

Yesterday I changed the fuel filter on my 1993 Merc 3.0. I am talking about the fuel filter that is inside of the fuel pump bowl. Now, it will start sometimes but will not stay running. After enough cranking, it gets to where it won't attempt to start at all. I have opened up the pump bowl a couple times after cranking and noticed that it's not completely full of fuel (maybe 1/2 - 3/4 full). I also cracked open the fuel line at the carb, and get a short-lived trickle at most, nothing most of the time. While it seems very odd, it seems that my fuel pump has quit at the very same time that I changed the filter (I know sounds crazy, I don't believe it myself). But I had the boat out the day before and it ran great. Yes, the tank has gas in it. Any thoughts? It is the original fuel pump as best I can tell. I even put the old filter back in, thinking maybe something was wrong with the new filter, but still same problem. Thanks in advance.

 

[alldodge]

Yesterday I changed the fuel filter on my 1993 Merc 3.0. I am talking about the fuel filter that is inside of the fuel pump bowl. Now, it will start sometimes but will not stay running. After enough cranking, it gets to where it won't attempt to start at all. I have opened up the pump bowl a couple times after cranking and noticed that it's not completely full of fuel (maybe 1/2 - 3/4 full). I also cracked open the fuel line at the carb, and get a short-lived trickle at most, nothing most of the time. While it seems very odd, it seems that my fuel pump has quit at the very same time that I changed the filter (I know sounds crazy, I don't believe it myself). But I had the boat out the day before and it ran great. Yes, the tank has gas in it. Any thoughts? It is the original fuel pump as best I can tell. I even put the old filter back in, thinking maybe something was wrong with the new filter, but still same problem. Thanks in advance.

Hope its not the pump but stuff does happen. To make sure, Get a gas can and some fuel line. Put the fuel line in the gas can coming from the pump/filter. If your problem goes away it may be the anti-siphon vale on the tank, or a restriction in the tank.

If you still have just a slight squirt or dribble of fuel then its probably the pump

 

[Bondo]

Ayuh,.... That fuel filter bowl is under vacuum from the pump, against both the head of fuel, 'n the anti-siphon valve at the tank's top,.....

If there's a speck of crud, 'n bad gasket/ o-ring, it Can't pump fuel,....

Recheck it, as ya say you've had it apart, alot,....

Test it with a remote tank as AD says, to rule out yer tank,...

 

[lgrouper03]

Thanks for the information, that gives me some good direction. I won't have a chance to get back to the boat now until next weekend. Once I get this resolved, I will post the solution. (I may go ahead and order a pump regardless, since mine appears to be the original one, 22 years old).

 

[fishrdan]

Check all hose connections, as they could be loose and sucking air but not leaking fuel. Also double check the filter and gasket. Even if the tank has fuel, is it covering the tank's pickup tube? My boat can have 1/2 a tank and not pull fuel, if the boat is sitting at a weird angle in the driveway, nose down attitude.