who has changed out there fuel pumps?

[topaz surfer]

Just trying to get some feedback on changing the low pressure and high pressure fuel pumps and the fuel pressure regulator? Anybody done there own? How bad and time consuming is it? Any tricks? Im not sure how to tell which part is bad so might have to change them all. Im going to test my fuel pressure at the rail but my cutting out problem is so eratic im not sure if it will tell me anything? Thanks guys. Motor is an 03 350 mpi tow sports merc.

[Tanner]

I've done both. To test the LP pump you can disconnect the output of the LP pump from the HP pump, turn on the key and see if fuel comes out. If it doesn't, then it's either your LP pump or the check valve at the fuel tank. You'll need to get access to the fuel tank to check the check valve.

Replacing the HP pump is really easy. The LP is easy as well, but a pain in the butt as you need to crawl behind the motor to disconnect it from the engine mounts. At least on the Marine Power motors.

Just a tip.... an impact drill with socket fittings will speed up the process a thousand times over.

[topaz surfer]

Sorry I left this info out but my problem is so random that I know the low pressure pump works because the boat runs fine 98% of the time. Just trying to plan ahead and not get stranded on the water or have a weekend ruined. Thanks for the input.

[boatwakes]

There is only one fuel pump on your engine and it's located on the starboard side engine forward motor mount. The fuel pressure regulator is mounted on top of the fuel pump and has an adapter to connect to the fuel line that you must also change. It's a PITA any way you look at it but I will bet the farm that's not your issue. Give us some more description of your cutting out issues: outside air temp, when does it happen, idle, full speed, morning, afternoon , stuff like that.

[topaz surfer]

I was also talking about the boost pump as the high pressure one. It has only happened while we are surfing at about 2800rpm and it also happened once when we were totally empty of ballast and cruising at close to wot across the lake at the end of the day. It just dies or loses power for a second and if you back off the throtle I have saved it once or twice from dieing. Other than that mtor starts right up and runs fine but I do think Im getting ready to replace the IAC valve because it has a light tendency to idle down really low when returnting to nuetral. When I scanned it the only thing that came up was puel pump circuit. But it seams to happen very randomly. Maybe three or fours times in an eight hour day. Sometimes I get the double beep and sometimes I don't. I'm just running out of time because we have a house boat trip next weekend and I'm not sure if I should change them all because I don't know how to tell which is the problem. It does seem to happen later in the day and its always above 75 air temp when we are out. Ideas?

[topaz surfer]

Oh and im trying to track down a fuel pressure tester and will do so tonight. My book and on the pump itself says 43psi. Should it always hold that or like you said in another post it would drop within 5 min? Thanks for the feedback.

[NICKYPOO]

I've changed put that exact same fuel pump and it wasn't too bad. It wasn't super easy but, you can hack it.

[topaz surfer]

I've changed put that exact same fuel pump and it wasn't too bad. It wasn't super easy but, you can hack it.

Did you change the regulator too? How long did it take you? How did you know yours was bad?

[NICKYPOO]

It comes as one unit. I'm not sure about any type of regulator in it. It is a fuel pump/cooler. It only took maybe an hour with taking my time. The hardest part is getting the hoses off.

When it went out, it just died right away. We were on the lake so it was working. Went to start the boat and it wouldn't start. I cycled the pump and you could tell it sounded sick. It was pretty obvious. I took it down to the dealership just so I could have Rick take a listen. As soon as I cycled it one time, he said, "Yep. Pump is dead." I put the new one in and cycled it and you could tell right away just by the way it sounded.

[topaz surfer]

Yeah I think mine will be a pita with it being a vdrive. Just hoping it doesn't die on me while on the water and ruin a weekend. Gona go out tonight with pressure gauge and run it on the lake.

[NICKYPOO]

That is the nice thing about having a D-Drive. I've got so much easy access to the motor its like cheating.