Mercury seawater/fuel pump
 

Last weekend i blew a oil seal out of the raw water pump and learned it has a cam for the fuel pump running in a gear oil reservoir. It made quite a mess from only 4 ozs. of oil and it tore the cam up from running it dry. I put a new water and fuel pump on today and decided to check the oil in the reservoir on the other motor and it was full of gas. So i put a new fuel pump on the other motor and hope the gas hasn't hurt the cam. What a chit rig for Mercury to design. These are 07 motors with 54 hrs. I know of several people here local who have had problems with the fuel getting in the oil. I guess electric fuel pumps and a blockoff plate on the water pump would fix it. If you have motors with this rig you need to check the oil in them. Has anyone else had problems with this ?

Same issue with the 500EFI setup too.

Warranty covered it didn't it Mark?

I had same problem but didn't leak as bad as yours.

Yup, I have worn the arm on 2 of mine. I now change the oil in mine every 50 hours (every other oil change) , seems like cheap insurance for me

Warranty covered the parts but not my labor and cleaning up the mess in my imaculate engine box :angry-smiley-044:

Same problem with my 575.
I change my oil every 25 hours and use Red Line Shockproof 75W90. It still has gas in it, and sometimes water too just to makle things more fun.
Some people I know don't ever change their's and never seem to have problems.........go figure?
Regards,
Steve

Same, routine checking on it during oil changes.

When I was at the Mercury factory earlier this summer I pointed it out to them. They were all ears.

Had the same issue with an older Formula and it actually cost me a motor due to fuel starvation. Expensive fix for a poor design.

I have gone thru 3 pumps so far. The fuel gets into the oil and then eats the seals out of the pump. Oil/gas mixture leaks past the seals and drips into the bilge. So now I have 2 sets of pumps and rotate them. While one set gets rebuilt, I use the other set until I see a leak. Then rotate them out - rebuilds in.

Pain in the azz. I did get rid of the stock Merc fuel pump and installed a billet pump from Keith Eikert. That set up does not leak as much gas as the Merc set up.

Did Merc NOT know about this problem???

I should have mentioned this too guys. As you know, it's nearly impossible to get all the old oil/gas/water out of the small reservoir when changing it. Last time mine was off, my mechanic (who agrees this is a ****ty design) drilled and tapped a drain in the bottom half of the housing, making changing the oil a LOT easier. You can see it in the 1st picture.
Bill, I switched to the Eickert pump too (more for flow/performance), and you're right, it doesn't seem to leak as bad as the stock unit.
Steve

What Merc motor is this?

Rage,
We have had this problem on the 500EFI and 575SCi Blue motors. I think it's going to be a problem on any Mercury with the one piece seawater/fuel mechanical pump. Some people never change their's until it craps out, because they don't know it's there.
I have just made it part of my regular 25HR service routine. I've been using Red Line in my supercharger, and since it's the best synthetic I've found, also in an application where gas contamination is a problem, I've been using it in the mechanical fuel pump too. I've also used Royal Purple 75W90 Max Gear. It's good stuff too.
Steve

525s with 54 hrs. Mercury does say to change the oil and inspect for fuel every 25 hrs. or 30 days whichever occurs first. The only way to get all the oil out is to remove the fuel pump. What a lame rig on a motor that cost this much. Zuckerman i like your drain rig. A West System epoxy syringe works great for putting the oil back in.

I've had my 502 mpi for about a year now and have not looked at this oil. Does anyone have some close up pictures of which plugs or fills to use, or procedures of how to get the oil out and how much to put back in?

Ryan

OMG, they have to know. I personally know of about 10 that have failed.
Just add it to Mercs other fine designs like Bravo uppers, gimbal rings, and couplers.

Look behind the seawater pump pulley on the right side of the housing in my first picture above (click on to enlarge). You'll see 2 screws. Yours will only have the top screw. You'll need a flexible piece of plastic hose and a syringe to suck the old oil out. It isn't easy. Another one of Mercury's great ideas. You would think they would have at least installed a drain screw like mine to make life a little easier.
Steve

HEY MARK, YOU SHOULD OF HAD ME DO THE JOB....

STAN

One of many reasons I shelved my Gen 5 motors inlew of Gen 4 with real fuel pumps and sep sea pumps...I hate those things.
Sorry you guys are having all this trouble.

I had those on my 525SC's...Had one go bad and rebuilt both, ran fine till I sold those motors.
Although, I agree with Zoom...

Haven't had any problems but when I do a fluid changeout I have gas in it.
Went to billet CV pumps but haven't ran them yet.
Hopefully this will be the answer.
If not electric fuel pumps are next.

Dennis

Maybe I'm one of the lucky ones ;)

Actually, I have done several upgrades with these setups and have always replaced the diaphram assembly with a Holley high volume diaphram assembly off of thier pump set up (note: you can not use the Holley armature assembly) Just remove the 6 (or 8, don't remember) and put in on in any rotation that fits your set up.
I have not had a failure or leakage on any of these. The old Merc/Carter stuff must not like the environment or like I said I may just be on of the lucky ones :)

Dave

I have not checked the fluid, but now I will.

Do all 525EFI's have mechanical fuel pumps?

I thought I had electric fuel pumps because I hear a 3-4 second prime when you turn the ignition key prior to starting. :confused:

You have a low pressure mechanical lift/feed pump and a high pressure electric pump.

Thanks Stan if its something i can't handle(like a drive:readinghelp: ) you'll be the first one i call.

Sal definetly check this when you do your first 20-25 hour oil change. I bet your enjoying that new boat :boat: :drink: :D

You know it Mark! :party-smiley-020:

3 weeks and 20 hours so far! I just finished the first fluid and filter change this week, but need to check the fluid in the seawater/fuel pump.

Thanks for the info. The mechanical pump seems pointless, but maybe there is a reason for the madness.

Gen V motors eliminated the block mount for a fuel pump. Cars with EFI use an electric pump in the tank, no need for it.
Electric pumps push better than pull fuel, so merc would have to set up a differnet configuration for every boat make in order to get electric tank mounted pumps to work. Add to that a long highly pressurized gas line from the tank to the engine = fire hazard.
So they put a mechanical pump on the sea water pump to pull fuel to the engine. The electric pump pressurizes the fuel for the injection.
Gary

any time you need help mark..
we are thinking of going to manteo nc me and frankie
want to go ?

He told me earlier in the week he was taking the crab boat down there. I think we're going to take a short cruise down to Smithfield Station for the night. :drink: :food-smiley-009:

I just checked my pumps today and the port engine seawater pump was full of fuel! The starboard engine seawater pump also had a good bit of fuel in it.

What a crock! :throw:

A couple of my buddys have checked theres this weekend and all of them had gas in them :eek:

Ditto, I've never had a problem...

In a similar note. I run the sea only and seperate electric fuel pump and mine burned the sea pump bearings up. They only have a minimal amount of grease on the shaft bearings. I purchased a new complete pump and drilled and tapped a hole at the centerline of the shaft and filled with gear lube. Bearing failure solved.

how is gas and water getting into the oil?

Looking at the seawater pump mounted fuel pump, can someone explain how to remove the arm off the old pump and the diaphram. I have several new engine mounted Merc pumps and hate to drop $160/ea for 2 new pumps.

I just read all of this and just can't believe Merc gets away with it. For the price they get for them. I am now glad my 525 is gone.:(

Activeshack,

How long were you running the boat after losing the oil? Was that engine starving for fuel which lead you to discover you lost the oil and the ruined pump?

TTT for good info.

I pulled my raw-water pump/fuel pump off tonight to change the oil and check the impeller, I've got about 110 hours on this impeller.

When I loosened up the fill screw on the oil reservoir it practically shot out, it was so full of extra gas.

I typically only put about 55-60 hours a year on it, last year was a good year. Just going to have to check it more frequently from now on.

As long as I have been exposed to this Mercury antiquated and somewhat stupid expensive mechanical fuel lift pump running off a very expensive proprietary Mercury water pump I have scratched my head and said:
Just remove the water pump/fuel pump, throw it away if bad, sell it if good and install a nice easy electrical low pressure efi type lift pump and connect it to the fuel pump relay and the inlet (tank feed) , connect it to the fuel line feeding the water seperator and install a standard inexpensive Bravo raw water pump on the bracket and BE DONE WITH THIS STUPID, EXPENSIVE, ANTIQUE SYSTEM! Come into the 21st Century!
There is no valid reason to stay with this expensive old system!

Best Regards,
Ray @ Raylar