1997 7.4 raw water w/fuel pump rebuild

[justavacation]

I discovered last week that my mechanical fuel pumps on the raw water pumps were leaking fuel into the oil reservoir on the pump body. I ordered new fuel pumps and removed the old ones expecting to see a cam on a shaft driven by the pulley. This would be the setup I'm used to seeing on old car engines. Instead, inside is a roller bearing with no cam and it moves back and forth on the shaft. The fuel pump was working before I removed it because the engines ran. Has any one taken these pump apart to rebuild the fuel pump side of the pump? The pump # is 46-807151A8. I know I can get the parts for it. Help :smt021

 

[LMBoat]

The pumps are said to be non-rebuildable. It's not an uncommon thing to get a bit of fuel in the lube reservoir.

 

[justavacation]

Thanks for the info. My oil reservoirs were comletely filled with gas and no oil. I'm new to this kind of setup. Is it usual for pumps to be shot with only 550 hrs. on the engines?:huh:

 

[my3sons]

It is not unusual for the oil in the pumps to be contaminated with a little gasoline. That is why it is important to change the oil annually. Usually if your diaphrams are bad, there will be gas in the tubing running up to the carbs from the fuel pump. That is the purpose of that tubing, to let you know you have a pump going bad. You say that the oil chamber of the water pump is full of gas and no oil, could it be that maybe the previous owner never changed the oil and it is badly contaminated? The part that you say slides back and forth on the shaft is the slip ring and if I remember right, it moves back and forth about 1/4 inch over the top of the cam. If the seal does not leak oil and the bearings are good, you may not need to rebuild the seawater pump. Regardless, at least you caught the problem and are on the road to getting it fixed. The pumps are rebuildable and I have done it twice. I bought a spare pump for my 330 and then rotated it into service as I rebuilt the two pumps on the engines, ending with a rebuilt one as the spare. You can get the parts at any merc parts supplier.
The water pump body usually has one fill port, and to remove the old oil requires sucking it out with a small pump or syringe with a piece of small diameter tubing attached.To get around this, you may be interested in doing the following. When you rebuild your pumps, after you remove the bearings and seals and have just the empty housing, you can drill and tap it (3/8-16) at the bottom of the reservoir for another plug. Use a lower unit plug with the magnetic tip in the new bottom port. Here is a picture from when I sold my spare pump and spare impeller from the 330, you can see the bottom plug I installed, to show the location. Draining and filling is a piece of cake with this setup.
Take care

I edited this to include a link showing all the parts in case you didn't have a schematic
http://www.mercruiserparts.com/Show...11.png&inbr=2345&bnbr=12&bdesc=SEA+WATER+PUMP

 

[J Levine]

I have rebuilt both the pumps on my motors and just finished rebuilding two more, a spare for me and a spare for a buddy. There are 5 bolts with 1/2" heads that secure the plastic raw water pump to the frame. One of the bolts has a nut on it and the other 4 hold the frame one to the bracket on the motor. Remove the drive belt and fuel lines and then use a flex socket to remove the 4 bolts, and the entire pump come loose from the engine. You can than take the fuel pump off the frame and dump out the old fluid. On my boat I often dont even bother to remove the raw water lines as there is enough slack to dump out the oil without removing them. I then clean out the old oil with a little carb cleaner and then put in new oil and reinstall the fuel pump with a new gasket and some Perfect Seal. I do this every fall as the oil goes to Hell fast. This is a very stupid design.

 

[Fun Times]

The oil that you will want to put back in the pump is the same oil you use on your Sterndrive. MerCruiser high performance gear lube plus.

http://www.mercurymarine.com/otherproducts/maintenance/gearlubehp.php

 

[justavacation]

Thanks for all the responses. If the pump isn't leaking oil or water how do you know when to rebuild it? The slip ring turns smoothly. Is there an online service manual for the rebuild?:smt024

 

[my3sons]

I rebuilt mine because after the boat was about 7 years old one of the seals started seeping oil and slinging it around the ER. I had the spare and figured I would just replace the bearings and all the seals as long as I was doing it.
I had no manual per say, just the schematic of the parts. Maybe someone else has something on step by step procedures. It's fairly straight forward, pull the pulley, pop off the seals, the shaft is shouldered for the bearings so you have to press in the right direction (I think the shaft came out toward the front but can't swear to it anymore) reinstall, reseal and press the pulley back on. Make sure the pulley is on correctly as it is just a press fit and you wouldn't want it to come flying off at wot. Don't over tension the belt, that's what wears the seals and bearings (besides the pump being full of gasoline) as long as the belt doesn't slip, your good on tension.
If your seals aren't leaking and the shaft turns smooth and bearings are snug, dump out the old oil, put the fuel pumps on, fill'er up and go enjoy.

 

[LMBoat]

Point of clarification: I mean't the fuel pump is not rebuildable <from a marine stand point>

 

[J Levine]

Point of clarification: I mean't the fuel pump is not rebuildable <from a marine stand point>

Agreed. Again this is a stupid design. Some fuel vapor gets past the pump which was designed to be bolted to the side of a engine with a large crank case filled will quarts of oil that can absorb it.... not into like 4 ounces of sterndrive lube. After about my typical 50 hours of annual running time this oil turns to crap. This was a cheap way for Mercury to deal with the lack of a boss on the block on the Gen IV 454 for a mechanical fuel pump since GM had gone to fuel injection by the time the Gen IV came out.

 

[dgrumm]

I am having similar issues with fuel in the oil (more fuel than oil) and a small amount of seeping onto the stringer. How does the fuel get into the oil cavity? Is it the gasket that is between them? Pulley turns smoothly so I think the bearings are fine, but the seal should probably be replaced.

 

[J Levine]

The fuel pump is leaking and needs to be replaced as the fuel pump is not servicable. The leak you see on your stringer is the seal on the pump shaft leaking. If you have not serviced these assemblies recently, I would pull them both, check them for leaks and probably rebuild them. The parts are not that expensive and if you follow the instructions in the merc service manual it is not that difficult to do.