Stuck fuel pump on 2001 3.0 Mercruiser Inboard.

koletsos

Cadet
Joined
May 20, 2015
Messages
7
First time user, so real sorry if this has been covered. Short story bought a 2001 Four Winns w/3.0 Mercruiser inboard. Still had original fuel filter, but ran good. In frustration to change filter, I just removed the entire pump. Glad I did because the cleaning it needed couldn't have been done installed. The top carb return connection (small flexible yellow tubing) was completely clogged with what looks like bits of rust. I cleaned as good as I could. Now, that port is completely clogged and the pump is frozen solid, won't budge. And no, I didn't try the pump before I started cleaning that port, but guessing I caused the clog. So, any easy fix here or time to buy a new pump?
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
First time user, so real sorry if this has been covered. Short story bought a 2001 Four Winns w/3.0 Mercruiser inboard. Still had original fuel filter, but ran good. In frustration to change filter, I just removed the entire pump. Glad I did because the cleaning it needed couldn't have been done installed. The top carb return connection (small flexible yellow tubing) was completely clogged with what looks like bits of rust. I cleaned as good as I could. Now, that port is completely clogged and the pump is frozen solid, won't budge. And no, I didn't try the pump before I started cleaning that port, but guessing I caused the clog. So, any easy fix here or time to buy a new pump?

Howdy,

Welcome aboard!


Well, it's pretty unlikely you damaged the pump cleaning the "port".

The hose is there to direct fuel from a broken/punctured fuel pump diaphragm to the carb intake.

It prevents fuel from being pumped either into the engine crankcase or bilge by directing it to the carburetor where it can be burned. The hose is yellow so you would see it (once you saw the black exhaust smoke from a really rich mixture)

It's not really a prefect system but it's there to help prevent an engine compartment fire.

If your pump is "frozen solid", you'll want to know why so you should probably remove it again and see if you can operate it by hand. If you cannot and there's anything in that hose, the diaphragm probably has a hole in it..........and yes, you'll need to replace it. Not very many rebuildable pumps around anymore.

Most of us will want to know your serial number since Mercury Marine doesn't really go by year model as much as serial number. Many 3.0L engines had electric pumps on them.

Also, you can likely get a replacement pump right here from iBoats
http://www.iboats.com/Mercruiser-Fu...0123133--session_id.628774105--view_id.269820

Supporting iBOats supports the Forum!

You can also probably get one from Napa, and other places that sell Sierra parts.....

Regards,


Rick
 

wrench 3

Commander
Joined
Aug 12, 2012
Messages
2,108
I'm not sure what to say about your plugged port, although it doesn't sound like there was any gas in it, which is a good thing.
Now I don't know how strong you are, but as for myself, I have trouble depressing one of those pumps unless it's mounted in a vice. It's a very strong spring.
 

koletsos

Cadet
Joined
May 20, 2015
Messages
7
Thanks, but now I'm confused if I should be able to move the pump with my hand or not? I did take the 6 screws and open it up. The diaphragm was able to push in and no holes or tears. I peeled it back and was able to clear the rust clog from the overflow, and there was a lot rust grit in the spring area. Not sure how this was working so well, but it's in bad shape. I have it soaking in some wd40 just for the heck of it, but looks like it needs replace anyway.
 

Alumarine

Captain
Joined
Feb 22, 2005
Messages
3,684
As wrench said, you should be able to operate the pump by hand but it can be difficult.
Put it in a vise as he suggested and try and operate it.
 

koletsos

Cadet
Joined
May 20, 2015
Messages
7
Well, learn sumpthin' new everyday! I really expected to be able to hold it in two hands and easily operate the lever. Never would have thought it moves so little and is that tight. I have it all cleaned up and put back together, but still waiting for the engine gasket to come in before I can install it. Probably looking at Sunday now. Any other great tips on installing it? I understand there should be some resistance I have to push against to make sure it has contact. Is there any way, or do I need to prime the pump first?
 

wrench 3

Commander
Joined
Aug 12, 2012
Messages
2,108
It will self prime no problem.
If it's spring is pushing it out of line and you're having problems getting the bolts started, rotating the engine a bit should take most of the pressure of off it.
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Not sure how this was working so well, but it's in bad shape. I have it soaking in some wd40 just for the heck of it, but looks like it needs replace anyway.

This would have me wanting to replace it. With a pump that old that you took apart (and did not replace the diaphragm) , You run the risk of a leak on the pressure side (which would put fuel in the bilge) OR a leak on the vacuum (fuel inlet) side which would put air in the system and possibly cause fuel starvation at high power settings.

You might be able to see the fuel leak if it leaks enough to drip visible fuel..........but if it doesn't, it might leak enough to place enough vapor in the bilge to create an explosive fuel:air mixture.

fuel connections, lines, and pumps are not something anyone should "jury-rig" in an enclosed engine compartment.

If that pump is original (15 years old) and/or questionable, I would replace it.

Cheers,


Rick
 

wrench 3

Commander
Joined
Aug 12, 2012
Messages
2,108
Just for the record. I'm with Bondo and HT32BSX115, you should replace the pump, especially if the spring has rust damage. But the translucent hose should prevent fuel from getting into the bilge if the diaphragm fails.
 

koletsos

Cadet
Joined
May 20, 2015
Messages
7
Well, we had so much rain over the weekend, I had more time to think, and I just ordered a fuel pump from you! Hope to have it in Friday.
 

havoc_squad

Senior Chief Petty Officer
Joined
Mar 5, 2011
Messages
694
If its a mechanical fuel pump on that 3.0L and you use a new gasket, make certain you use the correct gasket part number for the specified serial number of your engine.

Otherwise there is a high likelihood your fuel system will over-pressure and flooding will occur.
 

koletsos

Cadet
Joined
May 20, 2015
Messages
7
Thanks everyone for the advise! I installed the new pump yesterday, and it started right up and ran good for the 5 minutes or so I let it warm up. I hope to get it on the lake sometime this week and give it a good workout. There are two different types of gaskets, one thicker cork and the other a normal thin paper. Mine had the thicker one installed, so that is the gasket I used and it seems to be doing the trick.
 
Top