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496 HO Fuel pump issue?

Old 06-15-2019, 10:44 AM
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Default 496 HO Fuel pump issue?

So, tried to start my engine up today for the first time after the winter. It did start as it normally does but died immediately, tried again a couple of times but it only ignited on a few cylinders and died so I understood that something was wrong. Fuel pump sounds normal when I turn the ignition on.
Checked the fuel line between the water separate filter and the fuel pump and it was dry. Poured some fuel in there and tried again, it fired right up but died after a couple of seconds. Did that a few times with the same result. It seems that the fuel pump doesn´t manage to draw fuel from the water separate filter (it is new and filled with fuel). No codes on the Scan tool. Engine is a 2004 @ 500hours Serial# OW008133. Last outing last fall it ran perfect from idle to wot. Hoping for some ideas what can have happen during the winter months?
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Old 06-15-2019, 12:52 PM
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Check fuel pressure
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Old 06-15-2019, 02:16 PM
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what he said, fuel pressure will tell you the story,i just changed both my pumps and all good again.
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Old 06-15-2019, 05:28 PM
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Originally Posted by TURBOED View Post
what he said, fuel pressure will tell you the story,i just changed both my pumps and all good again.
Thanks for the advice! Sure I will test the fuel pressure but since it is starving for fuel I think I know what the result will be.
If I´m right and it is a bad fuel pump I am curious which part of it that possible can have gone bad and if I have to change the whole fuel pump, which part number is it?
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Old 06-16-2019, 08:34 AM
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Originally Posted by SCANDINAVIAN View Post
Thanks for the advice! Sure I will test the fuel pressure but since it is starving for fuel I think I know what the result will be.
If I´m right and it is a bad fuel pump I am curious which part of it that possible can have gone bad and if I have to change the whole fuel pump, which part number is it?
usually there is 2 pumps but I’m not sure what generation fuel system you have,usually Bup will chime in and will be able to tell you or take pictures and show us
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Old 06-16-2019, 11:07 AM
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BUP has posted about this a LOT I’m the past. Some of the cool fuel systems had terrible issues with inside paint pealing and ruining injectors. Note, this is all AFTER your fuel filters.

Do not run the boat any more even in diagnoses until you check this potential problem area out.
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Old 06-16-2019, 11:19 AM
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For one he did good by posting his engine serial number for starters and he has mentioned the water fuel sep filter so he SHOULD NOT HAVE GEN 3 cool fuel system. GEN 3 was the paint peeler and there is no way around it period.

the gen 2 cool fuel has other issues but mostly weak fuel pumps over time and as always crud in the fuel system but thats all marine engines over time Some way worse than others.

There is one big reason why the high pressure fuel pump becomes weak over time for all GEN 2 cool fuel systems ? Anyone what take a guess instead of me posting the why ?

couple of simple test first to try ?

Key on only fuel pressure is ??

Cranking engine fuel pressure is ?

this would be my first testing steps and then a remote fuel tank with fresh gas and a primer bulb to prime the fuel system all hooked to your first fuel inlet side of the engine. And again testing fuel pressure key on is and while cranking the engine over ? Does the engine start and will it start if you keep priming the bulb ?

Last edited by BUP; 06-16-2019 at 11:25 AM.
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Old 06-16-2019, 11:51 AM
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Also when I did mine I did all new filters along with brand new fuel pressure regulator and screen at regulator,if you’re already there you might as well
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Old 06-16-2019, 12:21 PM
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This engine have 2 fuel pumps! Check if both work!
And serial number was wrong! Unknown in Merc system!
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Old 06-16-2019, 01:03 PM
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What hull is the motor in?just curious
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