Mercruiser fuel pump problems...need advice...
 

Hey guys, having a problem with my Mercruiser 330 horse 454 in my '88 241 Liberator. I installed a brand new Mercruiser big block fuel pump over the winter when I re-built the motor. It ran fine for a couple months and then started flooding over after idling for a minute or two. I re-built the carb 3 times, until I did a fuel pressure test and found the mechanical pump putting out 12 psi at idle!!! This was too much pressure for the Q-jet, and was causing it to flood over. I replaced the pump with another brand new Merc pump, and now it idles perfect, BUT the boat won't hit high RPM! It bucks like hell and is running out of fuel over 4000 RPM. I did another test and found only 3-4 psi from this pump...AGGGHHH!!!

My question is, is there a better mechanical pump that i can buy that will actually put out the 6-7 psi that I need??? Thanks!

Once having those motors in my boat, I am familar with those mechanical fuel pumps on the raw water pump. Suggest you upgrade to these:
http://www.keitheickert.com/p-12460-...6-engines.aspx

Don't forget to clean out the lube bath and refill with the correct lubrication.

My fuel pump bolts to the block, not to the raw water pump housing, but thanks for the link! Mine is a big block Alpha, and has the raw water pump in the drive, should have stated that!

Thats a great site, thanks for the link. Thinking about purchasing this one:

http://www.keitheickert.com/p-14089-...-chevy-v8.aspx

That's the one you want. You can also get those from Jeg's or Summit. Probably a little cheaper.

That pump is cheaper than the Mercruiser ones I bought! I hope it's made better, these new Merc pumps are junk. I wonder why the pressures are all over the place? My boss had the same problem with his new Merc pump, to much pressure, and flooding his carb over.

I just put on a Jeg's fuel pump mine runs perfect

Which one?

Cant remember the model # boats engines require alot more fuel delivery than a car Here it is Jegs brand model# 555-15961 110gph bbc they have a 80 gph but i went with more fuel delivery running around 450hp with edelbrock 750 carb

Oh yea $ 54.99 could not find a fuel pump with this gph at any store in town thats why i went to Jegs

You probably ought to know that if you ever have a boat fire, your insurance will NOT cover your loss if they discover that you are using a Non-marine fuel pump on the boat. Technically, they can refuse to cover ANY loss on the boat due to the unapproved fuel pump.

If you do run non-marine fuel pumps, it's your choice to do so, but I want to make sure you know that it is a choice that could have negative consequences later..

MARINE pumps are explosion-proof, have a dedicated vent fitting on the area above the primary diaphragm, and are designed to be plumbed to an above-the-throttle-plate fitting on the MARINE carb.

Last fuel pumps I put on a Carbed 502 were Carter mechanicals with a Crusader part number. I paid less than $80 apiece and I DID have to re-index the inlet position, but they worked great.

MC

You deffinately want the Holley marine version which you can get at Jegs.
http://www.jegs.com/i/Holley/510/712...oductId=751733

Firehawk, you could probably convert that Jegs pump into a marine style pump. I believe all you would need to do is drill out the plug thats in the upper half of the pump and install a nipple. (See the link to the holley marine pump) Then connect a hose and run it to your flame arrester. May have to put a fitting on your flame arrester if it doesn't already have one.
Picture of Jegs pump.
http://www.jegs.com/i/JEGS-Performan...rentProductId=

Picklejim will do thanks, needed a winter time project anyway. Doesnt look to tuff

Ahhhh. My bad. Just assumed that you had a raw water pump. With that BBC, I would highly suggest you consider a winter project of installing a raw water pump and either a hull or transom water pickup. Transom would be the preferred method. Do you really trust that tiny pump in the outdrive to supply the necessary amount of water to that BBC? Besides, the lower water inlets are to easy to get clogged and/or blocked. IMHO

Actually, that "tiny" pump in the drive is why I love this boat. I have had many different boats with big block Bravo's, and have had lots of overheat problems. Burning up sea pumps, restricted transom plate hoses, and temps all over the place. I tried a Merc offshore transom pick-up on my 242 Formula, and it was constantly clogging with sea grass and causing an overheat. This boat runs at 160 all day, every day. It has never overheated on me once. Every year I service the Alpha and install a new Merc pump and housing kit, and it works flawlessly for me. If I can get a fuel pump with stable pressures, I'll be all set...lol.

Randy, Stick with what works for you. Did you consider installing a fuel regulator AFTER the pump?