3.0L Merc carb questions.

[Chris Hays]

Re: 3.0L Merc carb questions.

Thanks for all the replys guys. This fuel pump was a brand new un-used unit out of the box, (Mallory i believe), what could be wrong with it to create an overpressure issue, (to heavy of a diaphram spring??), im sucking from a temporary fuel container as of now so there should be no sediment or crap in the system. Wonder if any of the fuel injected motors may use this pump, although i would think they would be electric.

 

[Fishermark]

Re: 3.0L Merc carb questions.

Fuel is not "sucked" out of a carb, it is "pushed" by atmospheric pressure.

This may not be of specific help for your problem, but the above statement is just not true. The fuel is in fact sucked out by the lower pressure that is induced by the venturi of the carb. The velocity of the air traveling through the reduced area creates a vacuum and pulls the fuel into the engine.

 

[JustJason]

Re: 3.0L Merc carb questions.

You sure about that fishermark?

 

[chiefalen]

Re: 3.0L Merc carb questions.

The fuel pump got to pump between 4-6 psi period. Why, when, where, or anything else is bs.

GET THE RIGHT PUMP, LOOK UP THE NUMBER AT THE TOP OF THIS PAGE.

Do not start fugazing around in the pump, it's new and should be sent back and replaced.

Thats the bottom line want to start a thread on how a carb works and discuss it kewl.

We could also discuss how a fuel pump works might put some nice info out.

 

[Fishermark]

Re: 3.0L Merc carb questions.

You sure about that fishermark?

Well... yes. That's the whole principle upon which a carb works. That's why they have a venturi. As I said, a vacuum is created which sucks the fuel out and into the airstream. It is the same principle that allows an airplane to fly. Air moving over the wings basically creates a vacuum - or lower pressure which "sucks" the plane into the air. It is the air pressure difference caused by air moving at different velocities. The shape of the wing causes the air to flow at different speeds which creates lower pressure. That's a little bit of an oversimplification, but that's the general principle.

My philosophy is once you know how something is supposed to work, then it becomes easier to find out why it doesn't.

 

[Chris Hays]

Re: 3.0L Merc carb questions.

The fuel pump got to pump between 4-6 psi period. Why, when, where, or anything else is bs.

GET THE RIGHT PUMP, LOOK UP THE NUMBER AT THE TOP OF THIS PAGE.

Do not start fugazing around in the pump, it's new and should be sent back and replaced.

I understand that this is the wrong pump for the application, and i WILL be getting the correct pump, im just interested in what this pump is from or what fuel system it would be used on

 

[Chris Hays]

Re: 3.0L Merc carb questions.

Hey guys, got some info on my fuel pump i need ya'll to check out, sent Ebay message to guy i bought it from, (a reputable marine supplyer in Texas), telling him my situation and that they sent me the wrong pump, this is the reply :-
'We did send the correct pump and I understand your situation. You may want to touch base with a local mechanic. The pump we shipped is a Carter OE pump. I called a mechanic here and he said the new ones DO put out 15 psi and on the older engines that require 6 psi, you need to install a regulator.'
Is this right, do i need a regulator? I can see that this would work but where would i get one, and what would be marine approved??

 

[JustJason]

Re: 3.0L Merc carb questions.

Interesting.....
I don't know what to say to that. I really have no idea if new ones put out 15psi or not. I would suspect not, as no carbed engine needs that high of a fuel pressure. But I do know that i've never had a problem with a fuel pump that came out of a Merc or Volvo or even OMC labeled box.
You may want to try Napa for a regulator. It's really just a restrictor that goes inline on the output side of the pump. I've never used one though. If you end up getting 1 you may have to cut and re-flare your steel tube.

Whats the part number on your box?

 

[a70eliminator]

Re: 3.0L Merc carb questions.

Brand: Holley
Product Line: Holley Mechanical Fuel Pumps
Part Type: Fuel Pumps, Mechanical
Part Number: HLY-12-327-35
Free Flow Rate: 225 gph
Maximum Pressure (psi): 16 psi
Inlet Attachment: Male threads
Inlet Size: -10 AN
Inlet Quantity: Single
Outlet Attachment: Male threads
Outlet Size: -8 AN
Outlet Quantity: Single
Quantity: Sold individually.

NOTHING SUCKS!

 

[a70eliminator]

Re: 3.0L Merc carb questions.

Carter GM60032 $128.99
Estimated Ship Date: 3/9/09




Brand: Carter
Product Line: Carter Mechanical Fuel Pumps
Part Type: Fuel Pumps, Mechanical
Part Number: CRT-M60032
Inlet Attachment: Stock
Inlet Size: Stock
Inlet Quantity: Single
Outlet Attachment: Stock
Outlet Size: Stock
Outlet Quantity: Single
Quantity: Sold individually.
Notes: Fits Chriscraft 153/2.5L 1974-1976, Chriscraft 181/3.0L 1977-1987, Idmar 181/3.0L, Kieaeffer, Marine Power 181/3.0L, Mercury Marine 1974-1975 and 1979-1987.

Does this one cover your application $128.00 Summit racing (maybe here @ Iboats will have it too)

 

[Chris Hays]

Re: 3.0L Merc carb questions.

Wife threw box out, but here's a link to the page i got it from.
http://cgi.ebay.com/ebaymotors/Mari...yZ124104QQihZ024QQitemZ370152655434QQtcZphoto

 

[chiefalen]

Re: 3.0L Merc carb questions.

I don't know what to say to this development. And i know for a fact the guy is good cause i bought my new shaft from him.

Got to say i learned something new today.

NOT SUCKS PUSH.

 

[fishrdan]

Re: 3.0L Merc carb questions.

Something doesn't sound right as you shouldn't have to add a separate fuel regulator to cut the pressure down. Seems like a huge liability suggesting that you need to redesign the stock fuel system by adding a regulator,,, when all you really need is the right fuel pump.

I bet the factory installed the wrong regulator spring in the fuel pump or it's a defect, maybe one in the same.

Try contacting Carter (Federal Mogul) directly and see what they say.

 

[Chris Hays]

Re: 3.0L Merc carb questions.

Guess im going on the hunt for a regulator, need this thing running!! Any ideas??

 

[Don S]

Re: 3.0L Merc carb questions.

You don't need a regulator, what you need it the right pump.
Forget the aftermarket and get the OEM pump and I will bet money things will work.
Mechanical pumps do not put out 15 psi on these engines. You had to be talking to a salesman without a clue what you are talking about.
We have a parts person like that. Have been trying to get him fired for a year because he is a BSer. He also doesn't know there is a difference between a 350 Chevy and a 9.9 hp Evinrude outboard. Yet people take his word for things . Grrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr.

PS: It's not just here, it's everywhere. The counter- people are not mechanics, they are the counter people. But boating customers always like them because they give them answers that they want to hear. May not be right (Usually not) but it's what the customer wants to hear.

 

[fishrdan]

Re: 3.0L Merc carb questions.

Yup ^^^

Also, the fuel line from the pump to the carb needs to be a metal tube all the way, no rubber hose splices (think fire ). If you hang a (heavy) regulator off the metal line it could fatigue the metal fuel line and cause a whole bunch of problems (think fire again ), so now you need to mount the regulator on a bracket secured to the engine,,, and then get all the metal fuel lines to line up properly.

Seems that it would be easier to get the correct fuel pump.

 

[Chris Hays]

Re: 3.0L Merc carb questions.

Just thought id give a conclusion to this thread, i got an OEM pump for it and everything runs great, (at least after i got power to the coil, didn't have the choke wires connected and for some reason this kills power to the coil hot wire ) Anyway thanks for the help, all i need now is an alternator, a mixture screw and the starter does not like to turn the engine over very well, like the battery is flat but im running it straight off my diesel pickup so i guess its time for a rebuild.