496 HO fuel pump upgrade
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496 HO fuel pump upgrade

  1. #1
    Some guys never learn. bocco's Avatar
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    Default 496 HO fuel pump upgrade

    Can someone recommend a fuel pump upgrade for 2005 496HO? A buddy has one that's got some performance upgrades and it seems to be loosing fuel pressure at wide open. Can't seem to find anything on the usual high performance marine sites. The regulator has already been upgraded to the adjustable one from Dana.

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    E-7 Sheepdog (ret) SmokinLowriderSS's Avatar
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    Quote Originally Posted by bocco View Post
    Can someone recommend a fuel pump upgrade for 2005 496HO? A buddy has one that's got some performance upgrades and it seems to be loosing fuel pressure at wide open. Can't seem to find anything on the usual high performance marine sites. The regulator has already been upgraded to the adjustable one from Dana.
    First upgrade is a fuel pressure gauge.

    If you are managing to maintain 4-5 psi as a minimum, you have plenty of pressure (4 is getting borderline).

    FInd out what you have for certain before shotgunning parts at it.

    The marine mechanical I bought from a local suplier (of marine parts) puts out 4-5 psi at idle, 9 psi to my 454 above 5 grand, and also feeds my 150hp nitrous plate system.

    No recollection what brand it is, and not a tag on it.
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  4. #3
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    Quote Originally Posted by SmokinLowriderSS View Post
    First upgrade is a fuel pressure gauge.

    If you are managing to maintain 4-5 psi as a minimum, you have plenty of pressure (4 is getting borderline).

    FInd out what you have for certain before shotgunning parts at it.

    The marine mechanical I bought from a local suplier (of marine parts) puts out 4-5 psi at idle, 9 psi to my 454 above 5 grand, and also feeds my 150hp nitrous plate system.

    No recollection what brand it is, and not a tag on it.
    Aaron,

    You might want to verify your statement "4-5 psi as a minimum, you have plenty of pressure (4 is getting borderline).?

    I don't believe that a 496HO will begin to fire with 5 psi. You seem to have forgotten that this is an EFI engine. Just sayin.

    I believe than an adjustable fuel pressure regulator may do the trick. If not I would call Dustin at Whipple. No doubt he can help

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    New here Beer:30's Avatar
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    43psi is the KOEO pressure.
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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    Aeromotive Fuel

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    Some guys never learn. bocco's Avatar
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    So this is a fuel injected motor. It's a 2005 496HO with all of the Raylar upgrades. Plus Dana exhaust and adjustable regulator. It runs lean and hot at wide open. It has had a gauge on it. Pressure drops a bit a wide open. It's set for 50psi. This motor has the fuel pump built into a cool pack assy that's supposed to cool the fuel so whats needed I believe is a pump that matches the physical size of the stock one but has greater capacity.

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    New here Beer:30's Avatar
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    Quote Originally Posted by bocco View Post
    This motor has the fuel pump built into a cool pack assy that's supposed to cool the fuel so whats needed I believe is a pump that matches the physical size of the stock one but has greater capacity.
    Not gonna happen, I don't think. But, you don't really need the cool-fuel unit. It would be easier to just add an Aeromotive pump and regulator to the system and by-pass all of the stock stuff.

    Raylar should have an upgrade that they use. Check with them on factory integration (or not).
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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    magnafuel is another good one.

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    Wink Devil's In The Details

    Bocco:

    If you are talking about Marinko's Raylar engine his problem, the real problem with his boat is now taken care of. It was not a fuel pressure problem, but a problem with engine vacuume under load dropping the fuel pressure because the air intake system was restricted by the back seat bulkhead crushing the flame arrestor inlet. Larry and I flew to Sacramento with our programmer and test systems and spent an entire day with him and his beautiful boat at Honker Cut on the Delta to make sure he does not burn up a second engine we built for him!
    Just thought I would get this thread well informed.

    Best Regards,
    Ray @ Raylar Engine

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    21 Daytona Outlaw's Avatar
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    Quote Originally Posted by Raylar View Post
    Bocco:

    If you are talking about Marinko's Raylar engine his problem, the real problem with his boat is now taken care of. It was not a fuel pressure problem, but a problem with engine vacuume under load dropping the fuel pressure because the air intake system was restricted by the back seat bulkhead crushing the flame arrestor inlet. Larry and I flew to Sacramento with our programmer and test systems and spent an entire day with him and his beautiful boat at Honker Cut on the Delta to make sure he does not burn up a second engine we built for him!
    Just thought I would get this thread well informed.

    Best Regards,
    Ray @ Raylar Engine
    Talk about customer service.....
    #55

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    Some guys never learn. bocco's Avatar
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    Quote Originally Posted by Raylar View Post
    Bocco:

    If you are talking about Marinko's Raylar engine his problem, the real problem with his boat is now taken care of. It was not a fuel pressure problem, but a problem with engine vacuume under load dropping the fuel pressure because the air intake system was restricted by the back seat bulkhead crushing the flame arrestor inlet. Larry and I flew to Sacramento with our programmer and test systems and spent an entire day with him and his beautiful boat at Honker Cut on the Delta to make sure he does not burn up a second engine we built for him!
    Just thought I would get this thread well informed.

    Best Regards,
    Ray @ Raylar Engine
    I am just trying to find out of fuel pump upgrades exist for these motors for my own personal knowledge. Nothing more.

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    Wink

    There are many fine fuel pump system upgrades that are available for many marine high performance engines. The most important part of that scenario is what is the engine type, cubic inch size and horsepower produced and its gallon per hour needs at highest rpms under full loads. If a stock fuel system is capable of providing the correct amount of fuel at the correct pressures during the greatest demands the engine is requiring, then no change in fuel system is going to make more power or be better than what the engine was equipped with. Some more important conditions are how did the boat builder plumb and size the fuel delivery system to the pump and filters, does the fuel filter/fuel water seperator stay clean and serviced allowing the proper fuel flow to the engine under all loads, is good uncontaminated fuel of the proper octane rating provided, and also has the engine been modified beyond the capacity of the modified engines standard fuel delivery system. No need to guess here, a good test with air fuel meter and fuel pressure guage will show whether a new increased size fuel system is needed. If however there are other factors limiting proper fuel delivery under load, then no mater the fuel pump and filter system, there is going to most likely be engine damage if the engine is operated at full loads with an undersize or restricted fuel delivery system. When in Doubt-Check it Out! Class dismissed.

    Best Regards,
    Ray @ Raylar

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    Some guys never learn. bocco's Avatar
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    Thanks Ray for the refresher course in auto shop1A-1B. There were not a lot of fuel injected engine when I learned that stuff back in 1972. But it's funny how all of the basic principles remain the same. And I had two auto shop teachers that did drill the basics into me. I did more math in auto shop than in math class back then. Point being that although I may not be an expert I do know enough to ask more questions than how much will it cost.

    Good detective work figuring out that I'm asking about Marinko's boat. Mike and I are houseboat partners and I'm pretty familiar with all of the issues that have been going on with the boat. I took a couple of rides in the boat last weekend and even spend some time tubing behind the boat with Mike's kids. I have been reluctant to ask any questions on this site because I knew you lurked on this site as well as offshoreonly. The only reason I actually mentioned that the boat had Raylar parts is because is a 496 and there are currently only two options for performance upgrades on these engines, yours or Whipple.

    You seem kind of defensive in your posts and I'm not sure why. Actually some people thought you where more offensive. I did not come on here pointing fingers or looking for someone to blame for what happened to Mike's boat. And I can honestly tell you that I don't have a strong opinion either way on that subject. My sole purpose in asking questions about the fuel pump or any other aspect of that motor is to gain information that may help prevent that motor from burning up again. Like you said. "When in doubt, check it out". So I like to ask questions and learn. Fortunately most of the knowledgeable people on this web site are very help full and happy to offer help when someone asks a logical question.

    So now that it's gone this far let's try to logically discuss the actual problem. I'm having trouble understanding how restricting airflow would cause a lean condition in this motor. That should act like a choke and cause the motor to run rich. But this is injection and not a carburetor. But the purpose of either system is to maintain the correct air fuel ratio. So it appears that Mercruiser uses a pressure regulator that adjusts based on a vacuum signal from the plenum. When manifold vacuum drops the regulator increases fuel pressure. Kind of like the old fashioned Holley power valve. What I can't figure out about this is that if you have less air, whether due to intake restriction or the position of the throttle valve then you should also have less fuel. That's what it's supposed to due. So it seems to me that the system is doing what it's supposed to due and the lean condition may be caused by something else. But I wasn't actually there watching the air fuel ratio or exhaust temps so I am asking questions not making statements. It also seems like the cost of a fuel pump upgrade is pretty cheap insurance in the grand scheme of things since it's cheaper than the cost of shipping a cooked motor from Livermore to San Diego.

    So one more question before I conclude the longest post I've ever done on any boating site. I noticed that your intake repositions the throttle body a little lower and more forward than the Mercruiser one. Which is why the flame arrestor was crushed against the back seat. Is this the first time your kit was installed in a Howard 25 Bullet?
    Last edited by bocco; 09-14-2009 at 04:28 PM.

  16. #14
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    VERY nice post bocco.

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