merc 4.3l Cool Fuel and Fuel Pump Replacement Question

Hi,

I have a 1999 Merc 4.3L EFI setup. Boat runs absolutely perfect from 0-3800 rpms. then starts to backfire. I back off the throttle and resumes running fine again.

How do you guy check your fuel pressure on these engines?

Also, has any one just swapped out the fuel pump and used the old cool fuel assembly? I see that they sell the pumps separately, but want to learn about what can go wrong in the fuel cooler assembly, if anything?

I have recently replaced the plugs, distributor, ignition modules, and fuel seperators, and added the booster pumps to fix the vapor lock issues I was encountering earlier this season.

If there's any links to videos etc...please share. I can't seem to find much.

Thanks in advance,

,,,"How do you guy check your fuel pressure on these engines? "

There's a schrader valve in the fuel rail near the injectors. (Looks like a tire valve.) Borrow a fuel test kit and hook her on here. See what pressure you get before and after it dies out.

Jeff

EFI `s . some domt have the valve, mercruiser sells a special fitting. or hit up a junk yard and get the 2 sections of a junk tubing and connect with a hose.

This is tbi= no schrader valve.

any thoughts on just replacing the fuel pump and not the cool fuel part?

Merc stopped selling the pump by itself because they wanted the cooler changed at time of pump failure. There were issues with blockage. The cool fuel assy, if it's the one under. The port motor mount, is a real mother to replace and you only want to do it once. Also inspect the regulator when it's out

okay thanks for the suggestion