1992 Mercruiser 4.3LX Water Separating Fuel Filter conversion

[nismo.hanson]

Hi Everyone,

I have a 1992 Mercruiser 4.3lx SN: 0D716964 with the inline fuel filter in the fuel pump. I bought a sierra kit to instal a water separating fuel filter in there instead. (oil filter looking unit)The instructions mention pluming it between the tank and the pump.

The instructions did not mention what to do with the old filter in the pump housing. can i just remove it? Leave it in and never change(this feels wrong but i'll ask anyway). The Mercruiser manual shows there should be another inline filter near the carb, but it appears to have been removed prior to my ownership of this vessel.

I made sure to purchase extra USCG approved fuel line for splicing.

Thanks for the help.
Rob

 

[James D. Evans]

Left mine in the pump and change it yearly even though it always looks new. Can't have too many filters I suppose. The inline near the carb is in the fuel inlet, you have to take the metal line loose from the carb. Its just a mesh screen. Good Idea to check it yearly also, its a last line of defense in keeping trash out of the carb.

 

[nismo.hanson]

Did some work on the boat this weekend, added the new water sep filter and about 1.5 ft of 3/8" fuel hose.

Is the oem filter on the mech fuel pump a stone type filter?

The boat struggles to get on a plane now, seems to be starved of fuel.seems like it cant pump with the new filer in the line. Thinking the fuel pump may need to be replaced.

Another mechanical or electrical fuel pump?

 

[nismo.hanson]

Also worth noting, last season running at WOT it would cutout, but ran great the smallest amount backed off from WOT.

 

[Alumarine]

Try bypassing your new water seperating filter to see if that helps.
I believe there is an In and Out port on the filter base as well. That might be critical for flow.

 

[nismo.hanson]

Finally got some nice weather the lined up on my days off from work. Tried bypassing the new filter, problem persists. Inspected the distributor cap and rotor, quite corroded. Replaced the cap and rotor and it runs like a champ!